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Quantifying the effects of the differential outcomes procedure in humans: A systematic review and a meta-analysis: DIFFERENTIAL OUTCOMES
Abstract
We present a systematic review and a meta‐analysis comparing the differential outcomes procedure to a nondifferential outcomes procedure among clinical and nonclinical populations. Sixty distinct experiments were included in the systematic review, 43 of which were included in the meta‐analysis. We calculated pooled effect sizes for accuracy (overall accuracy, test accuracy, transfer accuracy) and acquisition outcomes (latency, errors, and trials to mastery). The meta‐analysis revealed significant medium‐to‐large effect sizes for all three accuracy measures (pooled effect size range, 0.57 to 1.30). We found relatively greater effect sizes among clinical populations (effect size = 1.04). The single‐subject experimental literature included in the systematic review was consistent with the findings from the group studies, demonstrating improvements in accuracy and speed of learning for the majority of participants. Moderator and subgroup analyses suggest that discrimination difficulty may induce relatively larger differential outcomes effects. The results indicate that the differential outcomes procedure can be a valuable addition to reinforcement‐based interventions.
... In this case, both stimulus-response pairs would be paired with both reinforcers, thereby precluding the generation of any specific association between them. Initially described in non-human research (e.g., Trapold, 1970), the DOP has also produced consistent benefits in discriminative learning and visuospatial recognition memory in human experiments (Fuentes et al., 2023;McCormack et al., 2019). To account for these findings, several theoretical developments (namely the associative two-process theory) highlight that the pairing of outcomes with stimuli-response associations generates an additional source of information to guide response selection, the outcome expectancies, that is coupled with concurrent Pavlovian and operant conditioning, enabling its activation upon presenting the discriminative stimulus (e.g., Maki et al., 1995;Lowe et al., 2016;Lowe & Billing, 2017;Savage, 2004;Savage & Ramos, 2009). ...
... In their 2024 paper, participants receiving differential outcomes required less expression intensity to be able to identify Fear and Surprise compared to participants under NOP conditions. As the improvements generated via the use of the DOP are at least partly related to difficulty (McCormack et al., 2019), the authors of these studies suggested that further research could be developed to employ differential outcomes in populations that present impairments in this ability. One such population is people diagnosed with autism spectrum disorders (ASD). ...
... These were IAPS pictures 1463, 1440, 1710, 1750, 1812, and 1920. This change should not affect the effectiveness of the DOP, as human studies have found differential outcome effects employing a wide variety of conscious or unconscious outcomes (for a review, see McCormack et al., 2019). The experimental task was programmed using the ...
Previous research highlights impairments in the recognition of facial expression of emotion in individuals diagnosed with Autism Spectrum Disorder (ASD). Relatives of people with ASD may exhibit similar, albeit subtler, impairments, referred to as the Broad Autism Phenotype (BAP). Recently, the Differential outcomes procedure (DOP) has been shown to enhance this ability in young adults using dynamic stimuli, with fewer intensity levels required to identify fear and surprise. The present study aimed to extend these findings to adults diagnosed with ASD (ASD group), and relatives of people diagnosed with ASD (BAP group). A Bayesian Generalized Linear Model was employed for statistical inference. The results indicated that the ASD DOP group performed worse than the BAP DOP group in fear trials. The social dimension of autism negatively impacted performance in some conditions, while positive relationships were found between the repetitive behavior dimension and performance for the ASD group. The opposite pattern was observed in the BAP group. These results suggest the importance of considering different dimensions of autism when conducting research on its relationship with other variables. Finally, participants in both ASD and BAP groups required less intensity to identify certain emotions when the DOP was applied, highlighting its potential utility for improving dynamic facial emotion recognition.
... Subsequently, studies have been conducted in humans, revealing faster learning and retention in discriminative training in children (Esteban et al., 2014;Estévez et al., 2001), young adults (Molina et al., 2015;Plaza et al., 2011), and older adults (Plaza et al., 2018) after applying the DOP. McCormack et al. (2019) highlight in their meta-analysis that these improvements exhibit effect sizes ranging from medium to medium-large. The proposed mechanism underlying these enhancements involves the generation of unique outcome expectancies that are activated when the stimulus is detected via an implicit stimulusoutcome Pavlovian association (Carmona et al., 2019;Maki et al., 1995). ...
... The authors discussed that the high accuracy of participants might indicate ceiling effects, with tasks not being challenging enough for them. As the effect of the DOP depends on the difficulty of the tasks with respect to participants (McCormack et al., 2019), and participants can present lower accuracies when labeling facial expressions of complex emotions (e.g., 75% mean correct responses for basic emotions vs. 62% mean accuracy for complex emotions in Benda and Scherf (2020)), assessing the recognition of non-basic emotions while using the DOP could mitigate this potential ceiling effect, thereby broadening the potential applications of this procedure. In a design similar to that of Carmona et al. (2020a,b), but employing a facial expression of emotion task, we would expect several of the ERPs that they report to appear here as well. ...
... An a-priori power analysis was conducted using G * Power 3.1.9.7 (Faul et al., 2007) for a mixed ANOVA with Group (DOP or NOP) as between-subject variable and Emotion (Affectionate, Attracted, Betrayed, Brokenhearted, Contemptuous, and Desirous) as within-subject variable. The analysis employed α = 0.05, power = 0.80, and a medium-to-large effect size (η 2 p = 0.1), which is about the typical effect size found in tasks that involve the DOP (McCormack et al., 2019). We set the correlation among repeated measurements to 0, as most accuracy correlations between emotions in an unpublished behavioral pilot study were nonsignificant. ...
The differential outcomes procedure (DOP) is an easily applicable method for enhancing discriminative learning and recognition memory. Its effectiveness in improving the recognition of facial expressions of emotion has been recently explored, with mixed success. This study aims to explore whether the expectancies generated via the DOP are reflected as differences in event-related potentials (ERPs) between participants in differential (DOP) or non-differential conditions (NOP) in a facial expression of complex emotion label task. Participants (n = 27 total, 14 DOP) in the DOP group received a specific reward for each specific emotion, while those in the NOP group received a random reinforcer when they correctly identified the emotion. We did not find differences in participants' accuracy or reaction time depending on group (DOP or NOP). These findings suggest that the DOP may not provide significant benefits for tasks involving labeling complex emotional expressions. However, differences in ERP components were observed between both groups. Specifically, the NOP group showed an increased Late Positive Component during encoding, fronto-central P300 during memory maintenance of facial stimuli, and frontal, fronto-central, and central P300 during retrieval. These ERPs, taken together, suggest that the task was more attentionally demanding for the NOP group. Additionally, some markers identified in previous ERP studies on the DOP were absent, indicating that the outcome expectancies may not have been fully generated. Finally, there were also interactions between the valence of the facial stimuli, participant group, and some of the potentials, such as N100 or N200 during encoding. These findings suggest that participants in the DOP group may have allocated more attentional resources to processing expressions of positive-valence emotions during earlier stages, possibly due to reward expectancy effects.
... In the present framework, we offer guidelines for healthcare professionals and other relevant stakeholders (e.g., technology, intervention developers) for the design and application in clinical settings of cognitive interventions based on a relatively new approach, the Differential Outcomes Procedure (DOP). The DOP has been intensively investigated in laboratory settings (see Fuentes et al., 2023;McCormack et al., 2019) and has shown great potential for improving cognitive function in a wide range of clinical and non-clinical populations. There are also a number of recent technology-based applications using the DOP that are being tested in the context of interventions with healthy older adults and people with NCD (see section 3.3). ...
... Learning these associations is enhanced by rewarding these two rules differentially, e.g. with social praise in the 'night→yellow pill' pairing, and with a pleasant image of a landscape in the 'morning→pink pill pairing'. In experimental studies the effectiveness of the DOP is assessed by comparing performance with non-DOP control conditions (McCormack et al., 2019) where rewards are randomly administered after correct response (outcomes are not specific to the S-R association). ...
... Over the last two decades substantial research has been conducted focused on demonstrating the same cognitive effects in humans. A meta-analysis study by McCormack et al. (2019) found that the DOP, when applied to humans ranging from children to elderly adults, with or without clinical conditions, produces significant medium-to-large effect sizes for learning and memory improvements (as compared to a control non-DOP condition). Furthermore, McCormack et al. (2019) concluded that the DOP benefits are more pronounced in clinical populations including those with NCDs (e. g., studies with people with Alzheimer's Disease). ...
... Conditional discriminations may be more readily acquired if a different consequence is provided following responses emitted in the presence of different antecedent stimuli-this is the differential outcomes effect (DOE;McCormack et al., 2019). When arranging instruction for a conditional discrimination, the instructor provides different reinforcers following responses to each conditional stimulus. ...
... McIlvane and Dube (2003) posited that differential consequences increase the discriminability between antecedent and response relations and may promote the acquisition of the instructor-defined discriminations rather than faulty stimulus control. Basic research with humans and nonhumans and applied research with adults and children with and without disabilities supports DOE to enhance acquisition of conditional discrimination, especially in MTS arrangements (see McCormack et al., 2019, for a review). For example, Estévez et al. (2003) found that arranging differential outcomes in conditional discrimination training led to better accuracy and faster learning for 19 of 24 children and adults with Down syndrome. ...
... Over 40 studies on the DOE have been published, and a meta-analysis found medium-tolarge effect sizes (McCormack et al., 2019). Still, it is unknown how frequently the DOE is used in applied-behavior-analytic intervention. ...
Stimulus control involves being more likely to engage in a target behavior in the presence of a stimulus than in its absence. These stimuli are discriminative stimuli because they are correlated with reinforcement and increase the likelihood of a response under specific conditions. Stimulus control is an essential behavioral principle that helps us behave more effectively and efficiently in our environment. Also, stimulus control is important in many social and instructional situations and is often targeted in applied-behavior-analytic interventions. In this chapter, we focused on the control of auditory and visual stimuli in simple and conditional discriminations. In addition to explanations of different types of discriminations and parameters of auditory and visual stimuli, we described procedural arrangements that can be used to teach auditory and visual discriminations. Next, we described intervention strategies and procedural components that can be used to teach discriminations. Finally, we provided guidance on arranging instruction to promote appropriate stimulus control, detecting sources of stimulus control, and strategies to help mitigate faulty sources of control.KeywordsAuditory–visual discriminationConditional discriminationDiscrimination trainingSimple discriminationStimulus control
... This result is known as the differential outcomes effect (Trapold, 1970;Urcuioli, 2005). In addition to faster learning, studies have demonstrated better terminal accuracy and better retention (McCormack, Elliffe, & Virués-Ortega, 2019). ...
... For an excellent meta-analysis on the various different methodologies (and applicable effect sizes) found that incorporate DOT (as applied to animals and clinical/non-clinical human children and adult participants) see McCormack et al. (2019). The differential outcomes effect has been consistently found using an instrumental procedure consisting of a number of independent repetitions (trials) where the stimulus-response-outcome (S-R-O) contingencies remain the same throughout. ...
... An a-priori power analysis was performed for sample size estimation in the software package G*Power (Faul, Erdfelder, Lang, & Buchner, 2007) using the effect size specification option "as in SPSS", the effect size found specifically for the ToC procedure obtained via a metaanalysis study of McCormack et al. (2019), η 2 = 0.33, power = 0.8, and α = 0.05 resulted in N = 20. The participants were students from the University of Gothenburg aged between 20 and 44 years (M age = 27.74) with 9 males and 11 females. ...
The findings of differential outcomes training procedures in controlled stimulus-response learning settings have been explained through theorizing two processes of response control. These processes concern: i) a stimulus-response route, and, ii) an outcome expectancy route through which valuations of stimuli (typically auditory or visual) may be represented. Critically, under certain contingencies of learning, the interaction of these two processes enables a transfer of knowledge. Transfer is hypothesized to occur via implicit inference for response selection given novel stimulus-response pairings. In this article, we test this transfer of knowledge, previously only examined in individual settings, in novel social settings. We find that participants are able to achieve transfer of knowledge and suggest they achieve this through vicariously learning the differential valuations of stimuli made by the (confederate) ‘other’ involved in the task. We test this effect under two experimental conditions through manipulation of the information made available to participants observing the confederate other's choices. The results of EEG recordings are, additionally, evaluated and discussed in the context of social signalling and emotional and cognitive empathy. We also consider implications for clinical and technological social learning settings.
... The simple manipulation of arranging the outcomes so that they are unique and specific to the new stimulus to be learned has been shown to be effective in improving discriminative learning, and delayed memory recognition in animals and humans (e.g., [18,[60][61][62]). The effects in learning and memory found with DOT are robust and of a medium-large effect size, as shown in a recent meta-analysis [63], which support the great potential of this protocol for future clinical applications. ...
... Training group and Robot type were the between-subject factors, whilst Challenge level was the within-subject factor. The experiment was carried out with an expected medium to large effect size for Training group, with respect to McCormack et al.'s [63] meta-analysis (power = 0.8), (power calculation with MorePower 6.0.4) [65] with at least 72 participants. Dependent variables were quantitatively measured and analysed based on data gathered from the gamified task (Accuracy: percentage of correct responses over each level), together with evaluation based on measures of affective ratings using the Self Assessment Manikin Scale (SAM). ...
This study represents the first stage of evaluating whether cognitive training interventions may be facilitated by the presence of a socially assistive robot (SAR) and gamification. Our experimental setup involves using a SAR providing feedback to a gamified visuospatial working memory task, administered according to a differential outcomes training (DOT) protocol. The study's main objective was to investigate whether performance and attitude towards the task would be affected by different robotic setups (none, simulated or physical) and in relation to different challenge levels. We measured performance accuracy on the gamified visuospatial memory task and self-reported affective ratings, which are relevant for assessing attitude towards the task and providing indicators to the potential for using a SAR for a longer-term cognitive intervention. Additionally, we conducted exploratory analyses of eye movement strategies for memory encoding during the task. The results demonstrated a significant differential outcomes effect (DOE) on memory performance accuracy, regardless of Robot type and Challenge level, providing evidence that a DOE can still be obtained when a SAR interacts with participants. Moreover, the results from the affective ratings revealed that participants accompanied by the physical robot reported lower levels of stress and increased levels of control. Our results demonstrate, for the first time, a DOE using a SAR in a gamified context. This result, coupled with positive subjective reporting of the human-robot interactive experience of participants, demonstrates the potential for using a SAR to: (i) promote positive attitudes for a DOT-based cognitive intervention, without (ii) negatively affecting task performance.
... In this case, both stimulus-response pairs would be paired with both reinforcers, thereby precluding the generation of any specific association between them. Initially described in non-human research (e.g., Trapold, 1970), the DOP has also produced consistent benefits in discriminative learning and visuospatial recognition memory in human experiments (Fuentes et al., 2023;McCormack et al., 2019). To account for these findings, several theoretical developments (namely the associative two-process theory) highlight that the pairing of outcomes with stimuli-response associations generates an additional source of information to guide response selection, the outcome expectancies, that is coupled with concurrent Pavlovian and operant conditioning, enabling its activation upon presenting the discriminative stimulus (e.g., Maki et al., 1995;Lowe et al., 2016;Lowe & Billing, 2017;Savage, 2004;Savage & Ramos, 2009). ...
... In their 2024 paper, participants receiving differential outcomes required less expression intensity to be able to identify Fear and Surprise compared to participants under NOP conditions. As the improvements generated via the use of the DOP are at least partly related to difficulty (McCormack et al., 2019), the authors of these studies suggested that further research could be developed to employ differential outcomes in populations that present impairments in this ability. One such population is people diagnosed with autism spectrum disorders (ASD). ...
Previous research highlights impairments in the recognition of facial expression of emotion in individuals diagnosed with Autism Spectrum Disorder (ASD). Relatives of people with ASD may exhibit similar, albeit subtler, impairments, referred to as the Broad Autism Phenotype (BAP). Recently, the Differential outcomes procedure (DOP) has been shown to enhance this ability in young adults using dynamic stimuli, with fewer intensity levels required to identify fear and surprise. The present study aimed to extend these findings to adult diagnosed with ASD (ASD group), and relatives of people diagnosed with ASD (BAP group). A Bayesian Generalized Linear Model was employed for statistical inference. The results indicated that the ASD DOP group performed worse than the BAP DOP group in fear trials. The social dimension of autism negatively impacted performance in some conditions, while positive relationships were found between the repetitive behavior dimension and performance for the ASD group. The opposite pattern was observed in the BAP group. These results suggest the importance of considering different dimensions of autism when conducting research on its relationship with other variables. Finally, participants in both ASD and BAP groups required less intensity to identify certain emotions when the DOP was applied, highlighting its potential utility for improving dynamic facial emotion recognition.
... Another type of (associative) learning, born out of non-human and humananimal learning traditions using either implicit or explicit rewards, is differential outcomes training [16]. Differential outcomes training (DOT) concerns the learning of stimulus-response-outcome associations where 'outcomes' are typically conceived of as specific rewards differential according to type, amount or some other property. ...
... So here a unique stimulusresponse pair leads to a unique (differential) rewarding outcome each time. This type of learning leads to increased accuracy and learning rate in humans [17] with a recent meta-analysis [16] also reporting medium-to-large effect sizes on learning speed and accuracy (DOT 'effects'). ...
Owing to the recent success of Large Language Models, Modern A.I has been much focused on linguistic interactions with humans but less focused on non-linguistic forms of communication between man and machine. In the present paper, we test how affective-linguistic communication, in combination with differential outcomes training, affects mutual learning in a human-robot context. Taking inspiration from child-caregiver dynamics, our human-robot interaction setup consists of a (simulated) robot attempting to learn how best to communicate internal, homeostatically-controlled needs; while a human "caregiver" attempts to learn the correct object to satisfy the robot's present communicated need. We studied the effects of i) human training type, and ii) robot reinforcement learning type, to assess mutual learning terminal accuracy and rate of learning (as measured by the average reward achieved by the robot). Our results find mutual learning between a human and a robot is significantly improved with Differential Outcomes Training (DOT) compared to Non-DOT (control) conditions. We find further improvements when the robot uses an exploration-exploitation policy selection, compared to purely exploitation policy selection. These findings have implications for utilizing socially assistive robots (SAR) in therapeutic contexts, e.g. for cognitive interventions, and educational applications.
... Therefore, fostering an accurate emotional facial expression recognition would thus be desirable, and methods that may ameliorate the possible deficits in this ability are worth investigating. The differential outcomes procedure (DOP) consists in an easy-to-apply and free-cost procedure that has been shown to improve learning rates and accuracy 8 . This procedure involves the association of a specific outcome with each stimulus-response sequence or stimulus to-be-recognised. ...
... Besides, for those interested in individual differences, schizotypal personality traits may not be only regarded as a clinical condition, but also a personality dimension aside from schizophrenia 35 , which study could be beneficial for social and affective sciences 26 . As impairments in the recognition of facial expressions of emotion can be expected in people with higher levels of schizotypal personality traits 36 and the DOP is increasingly beneficial as discrimination difficulty increases 8 , we can expect, if schizotypal personality traits have an effect on performance, that the DOP will provide a larger enhancement for those participants with higher schizotypal personality levels. ...
Emotional facial expression recognition is a key ability for adequate social functioning. The current study aims to test if the differential outcomes procedure (DOP) may improve the recognition of dynamic facial expressions of emotions and to further explore whether schizotypal personality traits may have any effect on performance. 183 undergraduate students completed a task where a face morphed from a neutral expression to one of the six basic emotions at full intensity over 10 s. Participants had to press spacebar as soon as they identified the emotion and choose which had appeared. In the first block, participants received no outcomes. In the second block, a group received specific outcomes associated to each emotion (DOP group), while another group received non-differential outcomes after correctly responding (NOP group). Employing generalized linear models (GLMs) and Bayesian inference we estimated different parameters to answer our research goals. Schizotypal personality traits did not seem to affect dynamic emotional facial expression recognition. Participants of the DOP group were less likely to respond incorrectly to faces showing Fear and Surprise at fewer intensity levels. This may suggest that the DOP could lead to better identification of the main features that differentiate each facial expression of emotion.
... The simple manipulation of arranging the outcomes so that they are unique and specific to the new stimulus to be learned has been shown to be effective in improving discriminative learning, and delayed memory recognition in animals and humans (e.g., [18,[60][61][62]). The effects in learning and memory found with DOT are robust and of a medium-large effect size, as shown in a recent meta-analysis [63], which support the great potential of this protocol for future clinical applications. ...
... Training group and Robot type were the between-subject factors, whilst Challenge level was the within-subject factor. The experiment was carried out with an expected medium to large effect size for Training group, with respect to McCormack et al.'s [63] meta-analysis (power = 0.8), (power calculation with MorePower 6.0.4) [65] with at least 72 participants. Dependent variables were quantitatively measured and analysed based on data gathered from the gamified task (Accuracy: percentage of correct responses over each level), together with evaluation based on measures of affective ratings using the Self Assessment Manikin Scale (SAM). ...
This study represents the first stage of evaluating whether cognitive training interventions may be facilitated by the presence of a socially assistive robot (SAR) and gamification. Our experimental setup involves using a SAR providing feedback to a gamified visuospatial working memory task, administered according to a differential outcomes training (DOT) protocol. The study’s main objective was to investigate whether performance and attitude towards the task would be affected by different robotic setups (none, simulated or physical) and in relation to different challenge levels. We measured performance accuracy on the gamified visuospatial memory task and self-reported affective ratings, which are relevant for assessing attitude towards the task and providing indicators to the potential for using a SAR for a longer-term cognitive intervention. Additionally, we conducted exploratory analyses of eye movement strategies for memory encoding during the task. The results demonstrated a significant differential outcomes effect (DOE) on memory performance accuracy, regardless of Robot type and Challenge level, providing evidence that a DOE can still be obtained when a SAR interacts with participants. Moreover, the results from the affective ratings revealed that participants accompanied by the physical robot reported lower levels of stress and increased levels of control. Our results demonstrate, for the first time, a DOE using a SAR in a gamified context. This result, coupled with positive subjective reporting of the human–robot interactive experience of participants, demonstrates the potential for using a SAR to: (i) promote positive attitudes for a DOT-based cognitive intervention, without (ii) negatively affecting task performance.
... Studies have shown that instead of using non-differential consequences, class-specific consequences may facilitate the acquisition of simple (e.g., Estéves et al., 2007) and conditional discrimination (e.g., Estéves et al., 2003;Morfín et al., 2018;Plaza et al., 2012). When using consequences that are class-specific, the procedure is known as differential outcome procedure (DOP), and the increase in accuracy is called the differential outcome effect (see McCormack et al., 2019). Moreover, in addition to facilitating the acquisition of baseline conditional discriminations, the procedure is also suggested to increase the likelihood of equivalence class formation. ...
... Another argument is that when using DOP, the subject will learn to anticipate the outcome, which serves as a discriminative stimulus for the subject's behavior (see Urcuioli, 2005). Elaborated discussion on potential mechanisms responsible for the change is out of scope for the current paper but readers may read McCormack et al. (2019) and Urcuioli (2005) for further elaboration. ...
The purpose of the current study was to (1) compare the acquisition of baseline conditional discriminations in younger and older adults using arbitrarily related abstract stimuli, (2) study the effect of the differential outcome procedure (DOP) on the establishment of baseline conditional discriminations, and (3) compare equivalence class formation in younger and older adults. Twenty-four participants, 12 younger adults (20¬–30 years old) and 12 older adults (67+ years old), participated in the study. In the conditional discrimination training, we gave the participants a break following 180 training trials, and the experimenter evaluated their progress. Participants with overall 50% correct responses or more after those 180 trials continued with the study as planned, with baseline conditional discrimination presented in accordance with the one-to-many (OTM) training structure and serialized training, followed by thinning of programmed consequences across training blocks before a test for the emergence of equivalence classes. If a participant was still training AB-conditional discriminations when the break was presented, with overall correct responses below 50% correct, the participant was exposed to a DOP to evaluate whether such a procedure may facilitate the establishment of the baseline conditional discrimination. Five participants in the older adult group received additional DOP training trials. The results show that two out of the five participants receiving DOP training established the AB baseline conditional discrimination—neither of those responded in accordance with stimulus equivalence. Two out of the other seven participants in the older adults group and six out of 12 participants in the younger group formed equivalence classes.
Key-words: stimulus control, conditional discrimination, stimulus equivalence, differential outcome procedure, younger adults, older adults
... Standardly, the differential outcomes training procedure entails a single stage of training over a number of learning trials where the objective is for participants to learn to associate different stimuli with different responses following repeated alternating presentations of each of the stimuli and all of the response options. The use of differential rewarding outcomes (for each correct stimulus-response pair) has been robustly found to speed up learning as compared to a non-differential (or common) outcomes control [3]. This is known as the differential outcomes effect. ...
... In memory training studies there can be a big difference in performance among target groups, e.g. young infants, elderly or adult students [3]. ...
This article adapts an existing experimental protocol for assessing individuals’ ability to transfer knowledge across instrumental and pavlovian learning stages. The protocol (Transfer of Control using differential outcomes learning) is adapted to fit social contexts wherein the pavlovian learning phase is modulated so that individuals are able to observe, and potentially learn from, the stimulus associated with reinforcing outcomes presented to another (observable) individual. Transfer of Control concerns participants combining knowledge of learned instrumental and pavlovian (stimulus, response, outcome) associations in order to ground the learning of new associations. The article describes the theoretical and procedural underpinnings of a novel Social Transfer of Control methodology. The use of such a methodology is two-fold: i) to serve as a guide to researchers interested in evaluating how individuals can learn from others in a partially observable setting, i.e. when behavioural and reinforcing outcome information is hidden, and bring to bear this knowledge on their own instrumental decision making; ii), to facilitate investigation of the routes of cognitive and emotional empathy, with potential applications for educational and clinical settings.
• Three stage Transfer of Control behavioural methodology is adapted to include a social (pavlovian) learning stage.
• Hypotheses can be tested that concern learning rewarding instrumental responses achieved by observation of others’ emotionally expressive reactions to differentially rewarding outcomes.
• Methodological and validation considerations for evaluating the above are presented
... In the current DO procedure, the association between the sample and choice stimuli is strengthened by the addition of a unique outcome rather than a generic one; correctly choosing C1 after the presentation of R1 will result in outcome O1, while correctly choosing R2 after the presentation of S2 will result in a different outcome O2 (Joseph, Overmier, & Thompson, 1997). This procedure is often used in clinical samples with memory impairments (e.g., autism, Down Prader-Willi, Korsakoff syndromes, and Alzheimer's disease) and has beneficial effects on learning and memory (Esteban, Plaza, López-Crespo, Vivas, & Estévez, 2014;Hochhalter & Joseph, 2001;Joseph et al., 1997;McCormack, Elliffe, & Virués-Ortega, 2019;Plaza, Molina, Fuentes, & Estévez, 2018;Urcuioli, 2005;Vivas et al., 2018). By changing the associative structure, there is a stronger memory for the correct association which potentially can overcome aDMTS performance especially under delayed conditions. ...
... This dissertation does not give any indications that children with ADHD respond less to remediation strategies, the data seem to point towards more (differential outcomes and reward) or equal response (stretching the ratios) to remediation strategies. Earlier research on DO has shown beneficial effects also in a non-clinical TD population (Esteban, Vivas, Fuentes, & Estévez, 2015;McCormack, Elliffe, & Virués-Ortega, 2019), something that we did not observe in our TD group. It may be that within our TD groups there was not enough room for improvement with the remediation strategies, leaving open the question whether children with ADHD respond equally or more than TD children to the remediation strategies. ...
... The second section compares the study outcomes or exposures with the possibility of adding two stars. The third section focuses on each primary study's outcome and statistical analysis, with the possibility of three stars [18]. We compared the quality assessment scores of the investigations and determined any difference before computing the final assessment score. ...
Background
Although Ethiopia is working towards measles elimination, a recurrent measles outbreak has occurred. To take appropriate measures, previously, many fragmented and inconsistent outbreak investigations were done, but there is no consolidated evidence on attack rate, case fatality rate, and determinants of measles infection during the measles outbreak. This systematic review and meta-analysis aimed to identify cumulative evidence on attack rate, case fatality rate, and determinants of measles infection during the outbreak.
Methods
A systematic literature review and Meta-analysis was used. We searched Google Scholar, Medline/PubMed, Cochrane/Wiley Library, EMBASE, Science Direct, and African Journals Online databases using different terms. Investigations that applied any study design, data collection- and analysis methods related to the measles outbreak investigation were included. Data were extracted in an Excel spreadsheet and imported into STATA version 17 software for meta-analysis. The I² statistics were used to test heterogeneity, and ‘Begg’s and ‘Egger’s tests were used to assess publication bias. The odds ratio (OR) with a 95% confidence interval (CI) was presented using forest plots.
Results
Eight measles outbreak investigations with 3004 measles cases and 33 deaths were included in this study. The pooled attack rate (A.R.) and case fatality rate were 34.51/10,000 [95% CI; 21.33–47.70/10,000] population and 2.21% [95% CI; 0.07-2.08%], respectively. Subgroup analysis revealed the highest attack rate of outbreaks in the Oromia region (63.05 per 10,000 population) and the lowest in the Amhara region (17.77 per 10,000 population). Associated factors with the measles outbreak were being unvaccinated (OR = 5.96; 95% CI: 3.28–10.82) and contact history (OR = 3.90; 95% CI: 2.47–6.15).
Conclusion
Our analysis revealed compelling evidence within the outbreak descriptions, highlighting elevated attack and case fatality rates. Measles infection was notably linked to being unvaccinated and having a contact history. Strengthening routine vaccination practices and enhancing contact tracing measures are vital strategies moving forward.
... A second difference in Experiment 2 was the use of class-specific reinforcement for three of the six rats. Class-specific reinforcement has been shown to enhance human discrimination learning in a variety of settings (e.g., McCormack et al., 2019McCormack et al., , 2021 and was a primary variable in the observation of functional classes in sea lions (Kastak et al., 2001). Although Mason et al. (2021) did not find effects of class-specific reinforcers with rats, these were introduced relatively late in the study after extensive training with a single reinforcer common to both sets had already taken place. ...
The simultaneous matching‐to‐sample procedures that are widely used to study stimulus equivalence in human participants have generally been unsuccessful in animals. However, functional equivalence classes have been demonstrated in pigeons and sea lions using a concurrent repeated reversal discrimination procedure. In this procedure, responding to one set of stimuli is reinforced but responding to a different set is not and the set associated with reinforcement is changed with multiple reversals during the experiment. The experiments reported here were designed to assess whether functional equivalence classes could be demonstrated in rats using similar techniques. Rats were initially trained with two sets of olfactory stimuli (six odors/set). Following many reversals, probe reversal sessions were conducted in which rats were exposed to a subset of the members of each set and, later in the session, the withheld stimuli were introduced. Responding to these delayed probe trials in accord with the reversed contingencies constituted transfer of function. There was some evidence of transfer in Experiment 1, but the effects were relatively weak and variable. Experiment 2 introduced procedural changes and found strong evidence of transfer of function consistent with the formation of functional equivalence classes. These procedures offer a promising strategy to study symbolic behavior in rodents.
... Methods used to detect asymmetry and publication bias are routinely employed in meta-analyses of group-design research. Although used less often in behavior analysis research compared to other fields, these methods are used in metaanalyses of behavioral research (see e.g., Amlung et al., 2016;McCormack et al., 2019) and meta-analyses of SCED studies (see e.g., Babb et al., 2020;Bowman-Perrot et al., 2014;Garwood et al., 2021;Shin et al., 2020). When attempting to aggregate behavior science research using frequentist statistical analysis, heterogeneity should be accounted for in the model minimally at the participant level (level 1) and the study level (level 2), referred to as a multilevellevel model meta-analysis (Becraft et al., 2020;Moeyaert et al., 2020). ...
Publication bias is an issue of great concern across a range of scientific fields. Although less documented in the behavior science fields, there is a need to explore viable methods for evaluating publication bias, in particular for studies based on single-case experimental design logic. Although publication bias is often detected by examining differences between meta-analytic effect sizes for published and grey studies, difficulties identifying the extent of grey studies within a particular research corpus present several challenges. We describe in this article several meta-analytic techniques for examining publication bias when published and grey literature are available as well as alternative meta-analytic techniques when grey literature is inaccessible. Although the majority of these methods have primarily been applied to meta-analyses of group design studies, our aim is to provide preliminary guidance for behavior scientists who might use or adapt these techniques for evaluating publication bias. We provide sample data sets and R scripts to follow along with the statistical analysis in hope that an increased understanding of publication bias and respective techniques will help researchers understand the extent to which it is a problem in behavior science research.
... In order to estimate the sample size needed, an a-priori power analysis was performed with G * Power [1] using the effect size specification option "as in SPSS", the effect size found specifically for the transfer of control procedure obtained via the meta-analysis by McCormack et al. [2] , eta squared = 0.33, power = 0.8, and alpha = 0.05 resulted in N = 20. The participants were 9 male and 11 female students at the University of Gothenburg, with ages between 20 and 44 years ( M = 27.74). ...
This article contains performance data, questionnaire ratings, and EEG data from a differential outcomes learning task from two experiments. In both experiments, the standard differential outcomes learning task was extended to involve a social dimension, in order to capture how people can learn from others by observation. In Experiment 1 (N = 20), using a within-subjects design, participants learned pairings of image stimuli in four conditions: 1) individual-differential outcomes, 2) individual-non-differential outcomes, 3) social-differential outcomes, and 4) social-non-differential outcomes. The social condition had a screen-captured video recording of the outcomes (but not the actions themselves) of another person performing the task. During the task, the performance of the participants was measured. After the task, participants rated their experience in a questionnaire. The procedure for Experiment 2 (N = 33) was similar to Experiment 1, but with a stronger social manipulation using a video of another person's face showing facial expressions reflecting the outcomes. In addition, EEG was measured while performing the task. For more insight, please see Vicarious value learning: Knowledge transfer through affective processing on a social differential outcomes task (Rittmo et al., 2020).
... The Differential Outcomes Procedure (DOP) consists in applying a specific outcome (e.g., picture of an object or animal) after each target stimulus or each distinct stimulus-correct response pairing. Typically, performance in both memory and learning tasks (better recognition, faster acquisition and/or higher response accuracy) is improved for DOP than for the non-differential outcome procedure (NOP), in which the outcome is not associated with a specific condition (NOP; for a review, see McCormack et al., 2019;Urcuioli, 2011). With regard to visual memory, this procedure has proved to be effective to improve: i) delayed recognition of objects in patients with Alzheimer's disease (Carmona et al., 2019b), in deaf children and in healthy children (Esteban et al., 2014b); ii) visuospatial working memory in mild cognitive impairment and in patients with Alzheimer's disease (Vivas et al., 2018), in children born prematurely (Martínez et al., 2012) and in healthy children (Esteban et al., 2015); iii) face recognition memory in children and in adults with Down's Syndrome (Esteban et al., 2014a), in older adults (López-Crespo et al., 2009) and in patients with Alzheimer's disease (Plaza et al., 2012). ...
The differential outcomes procedure (DOP) consists in applying a specific outcome after each discriminative stimulus-correct response pairing, leading to improved performance in both memory and learning tasks (faster acquisition and/or higher response accuracy), compared to the non-differential outcomes procedure (NOP). The main aim of this study was to explore the electrophysiological correlates (ERPs) of the DOP in a visual short-term memory task, and to test whether a differential activation pattern would be observed depending on the outcomes condition (DOP vs. NOP). The ERP signals showed differences between both outcomes condition in all three phases of the short-term memory task: encoding, maintenance and retrieval. Our results are in accordance with the view that in the DOP condition the probe stimulus triggers a representation of the unique outcome, which remains active over the maintenance period (prospective process). In the NOP condition, in contrast, a representation of the probe stimulus is maintained (retrospective process). In addition, these results suggested that stimuli associated with unique outcomes captured attention involuntary at retrieval, decreasing the interference from distractor stimuli in the retrieval phase.
... For instance, in the presence of a plate of soup, choosing the spoon may always be reinforced with the outcome "well done", whereas in the presence of a plate of pasta, choosing the fork may always be reinforced with the outcome "correct" (see Fig 1A for an illustration of the two outcomes procedures). The DOP has proven its effectiveness in improving discriminative learning in animals (see [20], for a review), children (e.g., [21]), university students (e.g., [22]), and patients (e.g., Down syndrome, [23]), and recent studies have extended its application to populations with recognition memory deficits (for a systematic review, see [24]). ...
Background
Adherence to treatment is a crucial factor for patients who have chronic illnesses or multiple morbidities and polypharmacy, which is frequently found in older adults. The non-adherence to medications has important economic and social consequences as well as impacts on the health of the patients. One of the reasons that can explain the low adherence to treatment, is the memory deficits that are characteristics of this population and that are even more evident in cases that involve neurodegenerative diseases.
Methods and findings
In this study, we explore whether the differential outcomes procedure (DOP), which has been shown to be useful in improving discriminative learning and memory in different populations, may facilitate learning and retention of medical recommendations in older adults who have been diagnosed with Alzheimer’s disease. The results demonstrate that when this procedure was applied, the patients showed improvements in learning and long-term retention of two pill/time of day associations in a situation that simulates adherence to medical prescriptions.
Conclusions
These findings contribute new data about the potential benefits of the DOP in patients with neurodegenerative disorders, highlighting the important role that this procedure could play in addressing important issues related to the health and quality of life of older adults, with or without neurodegenerative diseases, such as low adherence to medical treatments.
... Researchers interested in conducting metaanalyses of SCD should also become familiar with other guidelines and resources for metaanalyses (see for example McCormack et al., 2019). We also recommend the following resources for a comprehensive understanding of the meta-analysis process: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (http://www. ...
Meta-analyses provide a way to synthesize data across studies. However, this well-accepted method is infrequent with behavior analytic studies. A promising meta-analysis method for single-case data is multilevel models. In this technical article, we provide a primer for how to conduct a multilevel model with single-case designs with AB phases using data from the differential-reinforcement-of-low-rate behavior literature. We provide details, recommendations, and considerations for searching for appropriate studies, organizing the data, and conducting the analyses. We have also made all datasets available to allow the reader to follow along with this primer. Having studied this technical article, it is our hope that behavior analysts will be minimally equipped to complete a meta-analysis that will summarize a current state of affairs as it relates to our science and our practice. Moreover, we aim to demonstrate the value of analyses of this sort for behavior analysis.
Our behavioral units include stimulus classes and response classes. Peter Urcuioli's differential‐outcomes research implies they should extend to the third term of the three‐term contingency. Classes of consequences come in several varieties (e.g., conditional reinforcers, tokens), but our vocabulary does not coherently organize them. They are differentiated not only by physical properties such as type, location, and duration but also by the schedule contingencies in which they participate. We consider units ranging from the physical and chemical sciences to those based on the particular history of life on earth. The latter include biology, sociology, linguistics, and our own behavior analysis. Scientific units are typically nested (e.g., atoms within molecules, cells within organs, organisms within species). Comparing our units with those from other taxonomies raises questions about their emergence and evolution and their shared properties across levels of nesting (e.g., species within genus, subclasses within higher order operants, phonemes within words). Emergence necessarily occurs when higher order units have functions that are not shared with their lower order constituents. These nested and multileveled behavior classes challenge single‐level views, such as metaphorical accounts of behavior as a totality contained within a pie, with slices corresponding to behavior classes matched to their outcomes.
This paper presents a novel human-robot interaction setup for robot and human learning of symbolic language for identifying robot homeostatic needs. The robot and human learn to use and respond to the same language symbols that convey homeostatic needs and the stimuli that satisfy the homeostatic needs, respectively. We adopted a differential outcomes training (DOT) protocol whereby the robot provides feedback specific (differential) to its internal needs (e.g. ‘hunger’) when satisfied by the correct stimulus (e.g. cookie). We found evidence that DOT can enhance the human’s learning efficiency, which in turn enables more efficient robot language acquisition. The robot used in the study has a vocabulary similar to that of a human infant in the linguistic “babbling” phase. The robot software architecture is built upon a model for affect-grounded language acquisition where the robot associates vocabulary with internal needs (hunger, thirst, curiosity) through interactions with the human. The paper presents the results of an initial pilot study conducted with the interactive setup, which reveal that the robot’s language acquisition achieves higher convergence rate in the DOT condition compared to the non-DOT control condition. Additionally, participants reported positive affective experiences, feeling of being in control, and an empathetic connection with the robot. This mutual learning (teacher-student learning) approach offers a potential contribution of facilitating cognitive interventions with DOT (e.g. for people with dementia) through increased therapy adherence as a result of engaging humans more in training tasks by taking an active teaching-learning role. The homeostatic motivational grounding of the robot’s language acquisition has potential to contribute to more ecologically valid and social (collaborative/nurturing) interactions with robots.
How is it that we are able to respond to stimuli that are no longer present? To talk about events that occurred yesterday, last week, or a year or more ago? Is memory a limited store holding fading copies of our past? Or is remembering a behavior akin to seeing or hearing? The answers to such questions have important repercussions for whether and how we approach the task of improving a person’s remembering behavior. In this chapter, I describe who could benefit from remembering interventions. I present the views of memory held by cognitive and behavioral psychology and outline how the two positions affect approaches to improving memory performance. Lastly, I describe cognitive and behavioral interventions that can be applied by practitioners to improve memory performance.KeywordsRememberingDiscriminationTalking AloudAcquisition StrategiesConsequencesTraces
Ecological validity refers to how closely an experiment aligns with real‐world phenomena. In applied behavioral research, ecological validity may guide decisions about experimental settings, stimuli, people, and other design features. However, inconsistent use of the term ecological validity in the published literature has led to a somewhat disjointed technology. The purposes of this paper were to review current uses of the term “ecological validity” in the Journal of Applied Behavior Analysis, propose ways to make a study more ecologically valid, and develop a checklist to assist in identifying the type and degree of ecological validity in any given study.
When differential outcomes follow correct responses to each of multiple to-be-learned associations between a sample stimulus and a comparison stimulus (the differential outcomes procedure, DOP), performance is significantly better in comparison with when the associated stimuli and the outcomes are matched randomly (the non-differential outcomes procedure, NOP). In the present study we aimed to explore the effects of using the DOP versus the NOP in participants performing an eye-movement version of the matching-to-sample task. In the first phase, participants were presented with a sample stimulus followed by an associated comparison stimulus, and then a third stimulus served as the outcome that was presented according to the DOP or NOP scheme. In the second phase, after the sample stimulus, a comparison stimulus display was presented containing the associated stimulus (i.e., the relevant stimulus associated with the sample stimulus), the non-associated stimulus (i.e., the irrelevant stimulus associated with the other sample stimulus), and two distractor stimuli. Eye movements were recorded for each type of comparison stimulus. When we compared the pattern of eye movements between the DOP and NOP, we observed a tendency to produce a lower number of refixations to the associated comparison stimulus and a significant higher number of refixations to the non-associated and distractor comparison stimuli in the DOP compared to the NOP. These results suggest that in the first phase of the DOP, during each sample-comparison trial, the non-presented sample-comparison pair was inhibited, requiring more glances for identification during the second phase. Here we provide first evidence for the role of inhibitory processes in the context of the DOP.
The scientific literature points to physical exercise as an intervention that reduces behavioral limitations associated with autism spectrum disorder (ASD). The present study aimed to verify: (1) what hypotheses have been presented by behavior analysts about processes supposedly involved in the modifications of operant behaviors observed among participants diagnosed with ASD after physical activity and how these hypotheses have been investigated; and (2) what is the relationship between hypotheses provided in empirical analytical-behavioral studies and those presented by systematic review and meta-analysis studies. Research was performed on experimental and pre-experimental analytical-behavioral studies identified from: (1) references of systematic reviews and meta-analyses published between 2014 and 2020, found in the databases PsycINFO, SPORTDiscus, Education Resources Information Center, MEDLINE and Physical Education Index; and (2) screening of research reports published in behavior analysis journals, cited in systematic reviews and meta-analyses found. As a result, 10 analytical- behavioral studies were examined, and different hypotheses were identified to explain the positive effects of physical exercise on characteristic ASD behaviors. Among them, the following stand out: (1) changes in motivational variables produced by contingent sensory reinforcement to alternative behaviors of ASD behaviors as determinants of behavioral changes observed after exercise; (2) fatigue or aversive stimulation produced after exercise as a determinant variable of these changes; (3) brain and cognitive structures as determinants of changes in operant behaviors after exercise; (4) exercise as an alternative behavior that produces an escape of non-contingent demand, reducing the probability of ASD problem behaviors with this function; and (5) studies in which no hypotheses were suggested. In nine out of the ten studies, benefits related to the practice of physical exercise were reported on academic behaviors, repeating a sequence of numbers in reverse order (behavior related to executive function), and challenging behaviors. The hypotheses raised were, in some of the studies, supported by an adequate assessment methodology. Such studies used physical exercise as a strategy to ensure access to negative or sensory reinforcers, after prior evaluation that indicated that these conditions were responsible for maintaining the unwanted behaviors that were intended to change. Articles in which other hypotheses were suggested did not employ adequate methodologies to support them. This systematic review points to the importance of functional analyses prior to the implementation of the exercise as an intervention, since identifying the function of problem behaviors allows planning efficient and individualized interventions based on the practice of physical activity, which may vary, for example, in frequency, dosage and intensity.
Abstract
The simple manipulation of pairing specific outcomes with the sample stimuli strongly affects discriminative learning and memory processes. This procedure has been named the Differential Outcomes Procedure (DOP) and is usually compared to a control condition (the non-differential procedure, NOP) consisting in the random administration of the outcomes after each correct response. Recent research has revealed that the DOP effect arises even under unconscious conditions. In this study, we explored the temporal dynamics of short-term memory processes in both the DOP and the NOP in the absence of awareness of either the outcome (Experiment 1A) or the initial sample stimulus (Experiment 1B) through the evoked-related potentials technique. Results showed distinctive electrophysiological activation patterns in the DOP compared with the NOP at encoding, maintenance and retrieval phases. The present findings provide electrophysiological evidence of implicit-prospective processes involved in the DOP. They elucidate the processes that result in improved visual recognition memory.
Pairing discriminative stimuli with unique reinforcers provides an additional cue to correct responding. In the current study, we evaluated the effectiveness of the differential outcomes procedure in teaching novel tacts and facilitating transfer of tacts to novel discriminative stimuli. Four children diagnosed with developmental or intellectual disability were taught a unique pair of related tacts both under a differential outcomes condition and under a nondifferential outcomes condition where the reinforcers were uncorrelated with the sample stimuli. In the former, the different outcomes were two forms of the same reinforcer. Three out of four participants met the mastery criterion sooner under the differential outcomes condition. Two participants also generalized to novel stimuli under the differential outcomes condition. When we tested for the inclusion of the reinforcers in the stimulus class, three participants demonstrated the acquisition of emergent stimulus–outcomes and response–outcomes relations. The study provides support for the use of the differential outcomes procedure as a cost-effective means of enhancing the acquisition of discriminated responses in an applied setting.
Improvements in the quantification and visual analysis of data, plotted across non-standardized graphs, are possible with the equations introduced in this paper. Equation 1 (an expression of graphic scale variability) forms part of the foundation for Equation 2 (an expansion on the traditional calculation of the tangent inverse of a line’s algebraic slope). These equations provide clarification regarding aspects of “slope” and graphic scaling that have previously confused mathematicians. The apparent lack of correspondence between geometric slope (the angle of inclination) and algebraic slope (the m in y = mx + b) on “non-homogeneous” graphs (graphs where the scale values/distances on the y-axis are not the same as on the x-axis) is identified and directly resolved. This is important because nearly all behavior analytic graphs are “non-homogeneous” and problems with consistent visual inspection of such graphs have yet to be fully resolved. This paper shows how the precise geometric slope for any trend line on any non-homogeneous graph can quickly be determined—potentially improving the quantification and visual analysis of treatment effects in terms of the amount/magnitude of change in slope/variability. The equations herein may also be used to mathematically control for variability inherent in a graph’s idiosyncratic construction, and thus facilitate valid comparison of data plotted on various non-standard graphs constructed with very different axes scales—both within and across single case design research studies. The implications for future research and the potential for improving effect size measures and meta-analyses in single-subject research are discussed.
Working memory (WM) has been thought to be the cause of associative memory deficits in older adults. Previous research has demonstrated the benefits of a discriminative learning procedure, the differential outcomes procedure (DOP), to ameliorate such associative-memory maintenance deficits in situations that simulate adherence to medical prescriptions in both healthy and pathological ageing. Specifically, the DOP involves rewarding each correct response to each stimulus-stimulus association with a distinct and unique outcome (reinforcer). The aim of the present study was to explore the limits of this procedure by testing the amount of cognitive load at which the DOP improves discriminative learning and associative memory in a task that simulates adherence to medical treatment in undergraduate students. During the training phase, participants were asked to learn three pill/name (low-load condition) or four pill/name associations (high-load conditions) under the DOP in comparison with a control condition (the non-differential outcomes condition, NOP). Long-term retention of such learned associations was tested 1 h and 1 week after completion of the training phase. Participants showed a better accuracy and long-term retention of the learned associations when the DOP was used, but just in the high-load condition. These results suggest that when WM is overtaxed, the DOP plays a fundamental role in the long-term maintenance of the learned stimulus-stimulus associations, rendering such learning procedure as a useful technique to enhance people's discriminative learning and associative memory.
We advocate for rank‐permutation tests as the best choice for null‐hypothesis significance testing of behavioral data, because these tests require neither distributional assumptions about the populations from which our data were drawn nor the measurement assumption that our data are measured on an interval scale. We provide an algorithm that enables exact‐probability versions of such tests without recourse to either large‐sample approximation or resampling approaches. We particularly consider a rank‐permutation test for monotonic trend, and provide an extension of this test that allows unequal number of data points, or observations, for each subject. We provide an extended table of critical values of the test statistic for this test, and both a spreadsheet implementation and an Oracle® Java Web Start application to generate other critical values at https://sites.google.com/a/eastbayspecialists.co.nz/rank-permutation/.
Background
A meta-analysis as part of a systematic review aims to provide a thorough, comprehensive and unbiased statistical summary of data from the literature. However, relevant study results could be missing from a meta-analysis because of selective publication and inadequate dissemination. If missing outcome data differ systematically from published ones, a meta-analysis will be biased with an inaccurate assessment of the intervention effect. As part of the EU-funded OPEN project (www.open-project.eu) we conducted a systematic review that assessed whether the inclusion of data that were not published at all and/or published only in the grey literature influences pooled effect estimates in meta-analyses and leads to different interpretation.
Methods and findings
Systematic review of published literature (methodological research projects). Four bibliographic databases were searched up to February 2016 without restriction of publication year or language. Methodological research projects were considered eligible for inclusion if they reviewed a cohort of meta-analyses which (i) compared pooled effect estimates of meta-analyses of health care interventions according to publication status of data or (ii) examined whether the inclusion of unpublished or grey literature data impacts the result of a meta-analysis.
Seven methodological research projects including 187 meta-analyses comparing pooled treatment effect estimates according to different publication status were identified. Two research projects showed that published data showed larger pooled treatment effects in favour of the intervention than unpublished or grey literature data (Ratio of ORs 1.15, 95% CI 1.04–1.28 and 1.34, 95% CI 1.09–1.66). In the remaining research projects pooled effect estimates and/or overall findings were not significantly changed by the inclusion of unpublished and/or grey literature data. The precision of the pooled estimate was increased with narrower 95% confidence interval.
Conclusions
Although we may anticipate that systematic reviews and meta-analyses not including unpublished or grey literature study results are likely to overestimate the treatment effects, current empirical research shows that this is only the case in a minority of reviews. Therefore, currently, a meta-analyst should particularly consider time, effort and costs when adding such data to their analysis. Future research is needed to identify which reviews may benefit most from including unpublished or grey data.
A teaching intervention for face-recognition deficits in alcohol dementia (AlcDem) was tested. Participants viewed a sample face, and after a delay, chose which of two faces matched the sample. Under the Specific Outcomes teaching method, the reward for a correct identification was specific to the sample face (e.g., nickel for Face A, point for Face B). Under the comparison teaching method, Nonspecific Outcomes, the outcome was not unique to the sample. The AlcDem group performed with high accuracy similar to that of the Control group only with intervention. The data confirm that face-recognition deficits in alcohol dementia may be improved with simple behavioral interventions.
Numerous behavior analytic methods developed since the early 1960s have proved effective for developing a wide range of skills in learners with autism. Recent advances in stimulus control technology, in particular, offer effective methods for teaching many important skills and for promoting independent, generalized performances. This article reviews selected stimulus control techniques, including new methods for teaching conditional discrimination (matching) skills, stimulus equivalence procedures, prompt and prompt-fading techniques, and incidental teaching procedures.
Acquiring knowledge about the relationship between stimulus conditions, one’s own actions, and the resulting consequences or effects, is one prerequisite for intentional action. Previous studies have shown that such contextualized associations between actions and their effects (S-R-E associations) can be picked up very quickly. The present study examined how such weakly practiced associations might affect overt behavior during the process of initial learning and during subsequent retrieval, and how these two measures are inter-related. We examined incidental (S-)R-E learning in the context of trial-and-error S-R learning and in the context of instruction-based S-R learning. Furthermore, as a control condition, common outcome (CO) learning blocks were included in which all responses produced one common sound effect, hence precluding differential (S-)R-E learning. Post-learning retrieval of R-E associations was tested by re-using previously produced sound effects as novel imperative stimuli combined with actions that were either compatible or incompatible with the previously encountered R-E mapping. The central result was that the size of the compatibility effect could be predicted by the size of relative response slowing during ongoing learning in the preceding acquisition phase, both in trial-and-error learning and in instruction-based learning. Importantly, this correlation was absent for the CO control condition, precluding accounts based on unspecific factors. Instead, the results suggest that differential outcomes are “actively” integrated into action planning and that this takes additional planning time. We speculate that this might be especially true for weakly practiced (S-)R-E associations before an initial goal-directed action mode transitions into a more stimulus-based action mode.
The differential outcomes effect refers specifically to the increase in speed of acquisition or terminal accuracy that occurs in discrimination training when each of 2 or more discriminative stimuli is correlated with a particular outcome (e.g., type of reinforcer). The present review summarizes 38 studies concerned with the differential outcomes effect, provides a behavioral analysis of the phenomenon in terms of operant-respondent interactions, and offers suggestions for future research. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The differential outcomes procedure was evaluated during conditional discrimination training with three children with autism. Linking specific reinforcers to specific target responses did not produce large or consistent improvements in training efficiency compared to a nondifferential outcomes procedure. The results are discussed in the context of existing applied research on the differential outcomes effect and its relevance to skill acquisition technology. Copyright © 2010 John Wiley & Sons, Ltd.
Pigeons trained on many-to-one matching-to-sample with different probabilities of reinforcement for correct choice acquired
the task more rapidly and showed better working memory performance when those different probabilities were correlated with
the correct comparisons than when they were uncorrelated with them. Furthermore, this advantage was maintained when all correct
choices were subsequently reinforced at the same probability, even though the change to nondifferential outcomes produced
a drop in accuracy in the (formerly) correlated group. When birds were later shifted from correlated to uncorrelated outcomes
or vice versa, the original between-group differences were reversed or eliminated. These data suggest that differential outcomes
will potentiate matching performance if they generate an expectancy cue that is also predictive of correct choice. In addition,
different outcomes may enhance common coding of the samples in many-to-one matching to the extent that they too are correlated
with the correct comparison alternatives.
Previous studies have demonstrated the benefit of the differential outcomes procedure (DOP) in human learning. In the present study we aimed to explore whether the DOP might also help to overcome the face recognition memory deficit commonly observed in Alzheimer's disease (AD) patients.
A delayed matching-to-sample task was used. Participants were instructed to choose which of the 4 alternative faces (comparison stimuli) matched the previously seen face (sample stimulus). Either short (5 seconds) or long (25 seconds) delays were interposed between the sample and the comparison stimuli. In the differential outcomes condition each sample face was paired with its own outcome. In contrast, in the nondifferential condition, outcomes were randomly arranged.
The differential outcomes effect (DOE) was evident in the AD patients with both accuracy and latency data. That is, they showed a significantly better and faster delayed face recognition when differential outcomes were arranged. The analyses also revealed a significant main effect of delay; participants were slower in the 25 seconds condition than in the 5 seconds condition, but the difference was higher in the patients than in the controls.
These findings demonstrate, to our knowledge for the first time, that face recognition memory in patients with Alzheimer is improved when differential outcomes are used and draw attention to the potential of this procedure as a therapeutic technique.
Objective: Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we assessed the prevalence of bias in published meta-analyses. Design: Medline search to identify pairs consisting of a meta-analysis and a single large trial (concordance of results was assumed if effects were in the same direction and the meta-analytic estimate was within 30
"Pure basic" science can become detached from the natural world that it is supposed to explain. "Pure applied" work can become detached from fundamental processes that shape the world it is supposed to improve. Neither demands the intellectual support of a broad scholarly community or the material support of society. Translational research can do better by seeking innovation in theory or practice through the synthesis of basic and applied questions, literatures, and methods. Although translational thinking has always occurred in behavior analysis, progress often has been constrained by a functional separation of basic and applied communities. A review of translational traditions in behavior analysis suggests that innovation is most likely when individuals with basic and applied expertise collaborate. Such innovation may have to accelerate for behavior analysis to be taken seriously as a general-purpose science of behavior. We discuss the need for better coordination between the basic and applied sectors, and argue that such coordination compromises neither while benefiting both.
A number of clinical trials and single-subject studies have been published measuring the effectiveness of long-term, comprehensive applied behavior analytic (ABA) intervention for young children with autism. However, the overall appreciation of this literature through standardized measures has been hampered by the varying methods, designs, treatment features and quality standards of published studies. In an attempt to fill this gap in the literature, state-of-the-art meta-analytical methods were implemented, including quality assessment, sensitivity analysis, meta-regression, dose-response meta-analysis and meta-analysis of studies of different metrics. Results suggested that long-term, comprehensive ABA intervention leads to (positive) medium to large effects in terms of intellectual functioning, language development, acquisition of daily living skills and social functioning in children with autism. Although favorable effects were apparent across all outcomes, language-related outcomes (IQ, receptive and expressive language, communication) were superior to non-verbal IQ, social functioning and daily living skills, with effect sizes approaching 1.5 for receptive and expressive language and communication skills. Dose-dependant effect sizes were apparent by levels of total treatment hours for language and adaptation composite scores. Methodological issues relating ABA clinical trials for autism are discussed.
To date, very few studies have demonstrated the benefit of the differential outcomes procedure in human learning. In one of these studies (Maki, Overmier, Delos, and Gutman, 1995) there was evidence that normal children, ranging in age from 4 years and 6 months to 5 years and 5 months, performed better on a symbolic matching-to-sample task when they received differential outcomes following their correct responses. However, they only found facilitative effects of the differential outcomes methodology in 4-yearold children when the last eight trials were analyzed. In the present study, we used a similar task to that used by Maki et al. (1995) but we included a new phase for additional training. Participants, children ranging in age from 4 years to 4 years and 6 months, showed a better terminal accuracy and a faster learning of the task across the different phases when differential outcomes were arranged. These data indicated that additional training is not necessary to find the differential outcomes effect in 4-year-old children.
According to dual-system accounts, instrumental learning is supported by both a goal-directed and a habitual system. Although behavioral control by the goal-directed system, through outcome-action associations, dominates with moderate training, stimulus-response associations are thought to form concurrently in the habit system. It is therefore challenging to isolate the neural substrate of the goal-directed system in neuroimaging research with healthy human volunteers. Recently, however, de Wit et al. (2007) developed an instrumental discrimination task that distinguishes between goal-directed and habit-based responding. In this task, cues are congruent, unrelated, or incongruent with subsequent outcomes. Whereas performance on congruent and control trials can be supported by both the goal-directed and habitual system, performance on the incongruent discrimination relies solely on the habit system. In the present study, we used this task with healthy participants undergoing functional magnetic resonance imaging to demonstrate that engagement of the goal-directed system during learning is reflected in increased activity in the ventromedial prefrontal cortex. Moreover, using a subsequent outcome devaluation manipulation, we show that this area is involved in guiding decision making when goal values change, even in the absence of external cues to guide performance. We can therefore exclude a purely Pavlovian account of ventromedial prefrontal function and unequivocally demonstrate its involvement in the acquisition as well as deployment of goal-directed knowledge.
The effects of partial and total reversals of the sample-comparative contingency were evaluated in an matching-tosampletask with differential and non-differential consequences. Four groups of ten students each were constituted,two of them were trained in a matching-to-sample procedure with non-differential consequences, while the other twogroups were trained with differential consequences. After the training phase, the sample-comparative contingencyrelations were totally changed to one group of non-differential consequences and one group of differential consequences,while just one of the sample-comparative relation was changed to the other two groups. During the trainingphase it was observed that the groups trained with differential consequences obtained higher percentages of correctresponses that the groups trained with non-differential consequences. During the reversion phase it was observed thatin the four groups there was a reduction in the percentage of correct responses, being bigger in the groups trained withnon differential outcomes.
We present a revised version of the metareg command, which performs meta-analysis regression (meta-regression) on study-level summary data. The major revisions involve improvements to the estimation methods and the addition of an option to use a permutation test to estimate p-values, including an adjustment for multiple testing. We have also made additions to the output, added an option to produce a graph, and included support for the predict command. Stata 8.0 or above is required. Copyright 2008 by StataCorp LP.
The development of generalized conditional discrimination skills was examined in adults with retardation. Two subjects with histories of failure to acquire arbitrary matching under trial-and-error procedures were successful under procedures that trained one or more prerequisite skills. The successive discrimination between the sample stimuli was established by training the subjects to name the stimuli. The simultaneous discrimination between the comparison stimuli was established using either (a) standard simple discrimination training with reversals or (b) a procedure in which each of the two sample-comparison relations in the conditional discrimination was presented in blocks of trials, with the size of the blocks decreasing gradually until sample presentation was randomized. The amount of prerequisite training required varied across subjects and across successive conditional discriminations. After acquiring either two or three conditional discriminations with component training, both subjects learned new conditional discriminations under trial-and-error procedures. In general, each successive conditional discrimination was acquired more rapidly. Tests showed that conditional responding had become a generalized skill. Symmetry was shown for almost all trained relations. Symmetry trial samples were ultimately named the same as the stimuli to which they were related in training.
This study examined stimulus class membership established via stimulus-reinforcer relations. Mentally retarded subjects learned conditional discriminations with four two-member sets of visual stimuli (A, B, C, and D). On arbitrary-matching trials, they selected comparison stimuli B1 and B2 conditionally upon samples A1 and A2, respectively, and C1 and C2 conditionally upon B1 and B2, respectively. On identity-matching trials, they selected all stimuli as comparisons conditionally upon identical stimuli as samples. Throughout training, correct selections of A1, B1, C1, and D1 were followed by one reinforcer, R1, and those of A2, B2, C2, and D2 were followed by another, R2. Subsequent tests documented the formation of two four-member stimulus classes, A1-B1-C1-D1 and A2-B2-C2-D2. The class membership of the A, B, and C stimuli could have been based on equivalence relations that resulted from the arbitrary-matching training. D1 and D2 had never appeared on arbitrary-matching trials, however. Their class membership must have been based on relations with R1 and R2, respectively. Results thus confirm a previous finding that stimulus classes can be expanded via stimulus-reinforcer relations. They also define more precisely the potential nature of those classes and the conditions under which class membership can be established.
In an arbitrary matching-to-sample procedure, two mentally retarded subjects learned conditional discriminations with two sets of stimuli. Each set included a spoken name (N1 or N2), an object (O1 or O2), and a printed symbol (S1 or S2). One subject selected conditionally (a) O1 upon N1, and O2 upon N2, and (b) S1 upon O1, and S2 upon O2. The other subject selected conditionally (a) S1 upon N1, and S2 upon N2, and (b) O1 upon S1, and O2 upon S2. For both subjects, selections of O1 and S1 produced one type of food, F1; selections of O2 and S2 produced a different type of food, F2. Both subjects also learned identity-matching performances, selecting O1, O2, S1, S2, F1, and F2 conditionally upon those stimuli as samples; F1 followed selections of O1, S1, and F1; F2 followed selections of O2, S2, and F2. Matching performances consistent with stimulus class formation involving the names, objects, symbols, and foods were demonstrated on probe trials, even though these performances had not been taught explicitly. Next, new objects, X1 and X2, were presented on identity-matching trials, producing F1 and F2, respectively. Without further training, X1 was selected conditionally upon N1, S1, and O1, and X2 was selected upon N2, S2, and O2. When the contingencies were changed so that selections of X1 and X2 were now followed by F2 and F1, respectively, X2 was selected conditionally upon N1, S1, and O1, and X1 was selected upon N2, S2, and O2. Class membership of X1 and X2 had apparently changed. This study provides evidence that reinforcers may become members of stimulus classes, and that new stimuli may become class members through relations with reinforcers.
As evidence becomes increasingly important in educational policy, it is essential to understand how research design might contribute to reported effect sizes in experiments evaluating educational programs. A total of 645 studies from 12 recent reviews of evaluations of preschool, reading, mathematics, and science programs were studied. Effect sizes were roughly twice as large for published articles, small-scale trials, and experimenter-made measures, compared to unpublished documents, large-scale studies, and independent measures, respectively. Effect sizes were significantly higher in quasi-experiments than in randomized experiments. Excluding tutoring studies, there were no significant differences in effect sizes between elementary and middle/high studies. Regression analyses found that effects of all factors maintained after controlling for all other factors. Explanations for the effects of methodological features on effect sizes are discussed, as are implications for evidence-based policy.
In the last years, several studies have demonstrated that the differential outcomes procedure (DOP) facilitates both discriminative learning and short-term memory in different populations. It is worth to note that in most published studies exploring the usefulness of the DOP to improve memory, it has been used recognition memory tasks with neutral faces without emotional expressions. Our primary purpose in the present study was to test whether this procedure might increase performance of a facial recognition memory task when emotional facial expressions were used as comparison stimuli. Participants showed a significantly better delayed face recognition when differential outcomes were arranged. This novel finding adds information about how the DOP works and strongly suggests that this procedure can be a useful technique in applied contexts.
The effects of class-specific compound consequences embedded in an identity-matching task to establish arbitrary emergent relations were evaluated. A 3-year-old child with autism was taught identity relations between lowercase letters (Set 1) and uppercase letters (Set 2). A compound stimulus that consisted of an auditory component (dictated letter name) and a visual component (an uppercase letter for Set 1 or lowercase letter for Set 2) followed correct responses. All targeted arbitrary relations emerged (uppercase-lowercase, lowercase-uppercase, dictated name/uppercase, and dictated name/lowercase), suggesting that this procedure may be useful for teaching.
© Society for the Experimental Analysis of Behavior.
IntroductionIndividual studiesThe summary effectHeterogeneity of effect sizesSummary points
Objective:
The use of differential outcomes has been shown to enhance discriminative learning and face recognition in children and adults. In this study, we further investigated whether the differential outcome procedure (DOP) would also be effective in improving recognition memory for a wide range of stimuli with varying visual complexity (familiar objects, abstract stimuli, and complex scenes) in 5- and 7-year-old children.
Method:
Participants viewed a sample stimulus and, after a short (5s) or a long (15s) delay, they had to identify the previously seen stimulus among four choice alternatives. In the differential outcomes condition, each sample stimulus was paired with a specific outcome; whereas in the non-differential conditions outcomes were administered randomly. In Experiment 2, we replicated Experiment 1 but in addition we asked participants to perform an articulatory suppression task to prevent verbal rehearsal.
Results:
Children showed a greater overall visual delayed recognition when differential outcomes were arranged in both experiments. The type of stimulus being used modulated this effect; a beneficial effect of the differential outcomes training was evident with abstract objects in Experiment 1 and with both, abstract objects and scenes in Experiment 2.
The learning of the relations between discriminative stimuli, choice actions, and their outcomes can be characterized as conditional discriminative choice learning. Research shows that the technique of presenting unique outcomes for specific cued choices leads to faster and more accurate learning of such relations and has great potential to be developed into a training and pedagogical tool to help individuals with and without learning challenges better learn complex discrimination problems. We present a brief historical account of this technique, a theoretical and empirical analysis, and specific examples of the application of this training technique in everyday discrimination problems and in several traditional school subject areas. We conclude with the iteration that cognitive scientists and educational researchers need not overlook basic associative mechanisms that may be fundamental in subserving complex learning and memory processes.
Glass's estimator of effect size, the sample mean difference divided by the sample standard deviation, is studied in the context of an explicit statistical model. The exact distribution of Glass's estimator is obtained and the estimator is shown to have a small sample bias. The minimum variance unbiased estimator is obtained and shown to have uniformly smaller variance than Glass's (biased) estimator. Measurement error is shown to attenuate estimates of effect size and a correction is given. The effects of measurement invalidity are discussed. Expressions for weights that yield the most precise weighted estimate of effect size are also derived.
Behavior analysts in human service agencies are commonly expected to train support staff as one of their job duties. Traditional staff training is usually didactic in nature and generally has not proven particularly effective. We describe an alternative, evidence-based approach for training performance skills to human service staff. The description includes a specific means of conducting a behavioral skills training session with a group of staff followed by on-the-job training requirements. A brief case demonstration then illustrates application of the training approach and its apparent effectiveness for training staff in two distinct skill sets: use of most-to-least prompting within teaching procedures and use of manual signs. Practical issues associated with applying evidence-based behavioral training are presented with a focus on providing training that is effective, efficient, and acceptable to staff trainees.
Researchers have demonstrated that discriminative learning is facilitated when a particular outcome is associated with each relation to be learned. Our primary purpose in the two experiments reported here was to assess whether the differential outcomes procedure (DOP) would enhance 7-year-old children's learning of symbolic discriminations using three different forms of consequences in which (1) reinforcers are given when correct choices are made ("+"), (2) reinforcers are withdrawn when errors are made ("-"), or (3) children receive a reinforcer following a correct choice and lose one following an incorrect choice ("+/-"), as well as different types of reinforcers (secondary and primary reinforcers, Experiment 1; primary reinforcers alone, Experiment 2). Participants learned the task faster and showed significantly better performance whenever differential outcomes were arranged independently of (1) the way of providing consequences (+, -, or +/-) and (2) the type of reinforcers being used. Interestingly, as in a previous study with 5-year-old children (Martínez, Estévez, Fuentes, & Overmier, The Quarterly Journal of Experimental Psychology 62(8):1617-1630, 2009), the use of the DOP also enhanced long-term persistence of learning.
Three severely retarded children were given training on several two-choice discrimination problems. Each discrimination problem consisted of displaying two ordinary children's toys and asking the child to point to the toy named by the experimenter. The names consisted of three-letter (consonant-vowel-consonant) nonsense syllables. Training on each problem was conducted under one of three different reinforcement conditions. In the condition labeled “specific reinforcement,” correct choices were followed by the opportunity to play with the toy to which the child pointed. Under the “nonspecific reinforcement” condition, correct responses were followed by the opportunity to play with a toy offered by the experimenter, but which was not a part of the training pair. In the “variable reinforcement” condition, the child was offered, on correct pointing occasions, either the toy to which he or she pointed, or the toy which was not one of the pair being trained, in random order. The results indicated the level of correct responding was higher under the “specific reinforcement” condition than under either of the two other conditions, even when the latter were “weighted” for strength of reinforcement potential. It was concluded that a strategy of reinforcement which includes cue values of the discriminative stimulus may strengthen the learning process.
Five adults with Prader-Willi syndrome (characterized by short stature, learning difficulties, incomplete sexual development, and uncontrollable eating) learned the conditional relations necessary for the formation of two equivalence classes under differential/nondifferential and edible/nonedible outcomes. Performance on test trials was better when edible outcomes were used for four of the participants. (Author/DB)
Abstract How does the human brain translate symbolic instructions into overt behavior? Previous studies suggested that this process relies on a rapid control transition from lateral prefrontal cortex (LPFC) to anterior striatum (aSTR) and premotor cortex (PMC). The present fMRI study investigated whether the transfer from symbolic to pragmatic stimulus–response (S-R) rules relies on changes in the functional coupling among these and other areas and to which extent action goal representations might get integrated within this symbolic-pragmatic transfer. Goal integration processes were examined by manipulating the contingency between actions and differential outcomes (i.e. action goals). We observed a rapid strengthening of the functional coupling between the LPFC and the Basal Ganglia (aSTR and Putamen) and orbitofrontal cortex (OFC) as well as between the LPFC and the anterior dorsal PMC (pre-PMd), the anterior inferior parietal lobule (aIPL), and the posterior superior parietal lobule (pSPL). Importantly, only some of these functional integration processes were sensitive to the outcome contingency manipulation, including LPFC couplings with aSTR, OFC, aIPL, and pre-PMd. This suggests that the symbolic-pragmatic rule transfer is governed by principles of both, instrumental learning (increasingly tighter coupling between LPFC and aSTR/OFC) and ideomotor learning (increasingly tighter coupling between LPFC and aIPL/pre-PMd). By contrast, increased functional coupling between LPFC and Putamen was insensitive to outcome contingency possibly indicating an early stage of habit formation under instructed learning conditions.
Four adults with mental handicaps (aged 33–57 yrs) were taught to recognize (discriminate) sign language letters when presented as members of unchanging pairs (e.g., A and E, G and H). Correct responses were followed by food or verbal praise. Terminal accuracy was greater when a correct response to a given letter was followed consistently by a particular outcome (e.g., food followed correct responses to A and praise followed correct responses to E) than when nondifferential outcomes were arranged (e.g., food followed 50% of all correct responses and praise followed the remaining 50%, regardless of whether the responses were to A or E). (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The differential outcome effect (DOE) refers to the increase in speed of acquisi-tion and terminal accuracy that occurs in conditional discrimination learning when two or more stimuli are correlated with a particular outcome. Previous studies dem-onstrated the benefits of the DOE in preschool children. In two experiments we extended the DOE methodology to older children and tasks of different difficulty. Experiment 1 indicated that the DOE procedure improved conditional discrimina-tion performance of 4-to 7-year-old children. However, this effect was not present in children aged 8 years. In Experiment 2, we increased the difficulty of the task and demonstrated that these children in the differential outcome condition performed significantly better on this complex version of the discriminative task than those in the matched control group. It is proposed that the DOE is a general effect that is not limited to early stages of development and that the difficulty of the task is an important variable to consider when a differential outcome procedure is used.
The development of valid animal models of learning is especially important since learning is critical for nearly all aspects of human behavior and identifying appropriate surrogates provides additional opportunity to study various aspects of learning. Examining the factors that affect learning is often complicated by the need to administer the same task repeatedly across experimental conditions. Incremental repeated acquisition (IRA) tasks have been used extensively in animal research because they circumvent this problem by requiring a subject to learn different response chains repeatedly across sessions. The present study examined the association of age, sex of the participant, and IQ on the performance of an incremental repeated acquisition task in 837 children, aged 5-13 years. This task required children to learn to press four response levers in a specific sequence that was randomly chosen. Illumination of colored indicator lights signaled position in the required response chain. Initially, for the first link, only one of the four levers was correct: a response to it resulted in the delivery of a monetary reinforcer (5 cents). After mastery of the first link (i.e. three correct presses), the children were presented with a two-link response chain: a different lever had to be pressed before pressing the previously correct lever. After mastery of the two-link chain, the response chain length was once again increased, and so on until a response chain consisting of six links was completed or until the task timed out. Older children and children with higher IQs mastered longer response chain lengths and were more accurate in performance of this learning task than younger children. In addition, older children and children with higher IQs had higher effective response rates and lower ineffective response rates. No significant effects of the sex of the participant were demonstrated for any of the variables on this task, except overall response rate. The results indicate that this test is sensitive to developmental variables in children, with the degree of sensitivity of certain dependent variables being age-dependent. Characterization of performance of this task by humans facilitates comparisons with animal models employing the same task, thus enhancing its translational utility.
The present paper reports three experiments that examine the role of sample stimulus-outcome (S-O) and of comparison or choice response stimulus-outcome (R-O) relations in the differential outcomes discrimination learning of five-year-old children. In these experiments, S-O relations or R-O relations were maintained or removed across two different conditional discrimination tasks. The results indicated that only children who received training in either S-O or R-O relations showed positive transfer between the conditional discriminations. These data support a two-process (‘outcome expectancy’) account of differential outcomes phenomena in which each sub-problem in a discriminative conditional choice task has its own unique reinforcer, but they also indicate that both unique sample-outcome associations and unique choice-outcome associations are important contributing features to enhanced discriminative learning under differential outcomes procedures in humans. Comparison to a control in Experiments 2 and 3 indicated that merely having had previous experience with the stimuli or having previously discriminated the stimuli did not contribute to cross-discrimination transfer in the absence of prior explicit association between those stimuli and the specific differential outcomes.
Five male, nonverbal autistic children were trained on two-choice receptive label discriminations using three different reinforcement procedures in an attempt to determine which procedure would produce the highest rate of acquisition of the labels. The three procedures consisted of stimulus-specific reinforcement, in which a correct discrimination of each of the labels was consequated with a reinforcer unique to that label; salient reinforcement, in which all correct discriminations were consequated with a single, desirable reinforcer; and varied reinforcement, in which correct discriminations were randomly consequated with one or another reinforcer. Visual and statistical analyses of the data showed the specific reinforcement condition to be superior to the varied reinforcement or salient reinforcement conditions as measured by numbers of trials necessary for each child to meet criterion level of responding in each condition. The results tend to support a stimulus-reinforcer correlation hypothesis which suggests that rate of acquisition of new responses increases as the correlation between the discriminative stimulus and the reinforcer increases. Implications of the research are discussed in terms of motivation, language program planning and new research directions.
Two experiments are reported which bear upon the question of whether the expectancy aroused by a signal for solid food is discriminably different from that aroused by a signal for sucrose. The first experiment demonstrated in a response choice task that rats will learn to make R1 (pressing one of two bars) to S1 and R2 to S2 faster if correct S1-R1 occurrences are reinforced with food and correct S2-R2 occurrences with sucrose, than if both S-R chains are reinforced with the same agent. The second experiment demonstrated that rats learn the , problem faster if they have received pretraining in which S1 is simply paired with and S2 with than if the pretraining is the reverse of the stimulus-reinforcer pairings encountered in the choice task. These results are interpreted as indicating that different reinforcers establish distinctively different expectations which can function as part of the discriminative stimulus complexes for the correct responses.
We investigated whether search accuracy of adult humans could be enhanced using differential reward contingencies in landmark-based spatial tasks conducted on a computer screen. We found that search accuracy was significantly enhanced by differential outcomes in a conditional spatial search task, in which the landmark-to-goal relationship depended on a previously presented sample object (Experiment 4). In contrast, no significant differential outcomes effect (DOE) was seen in several other variations of spatial search tasks. We interpret the pattern of significant and non-significant results in terms of the information value of outcome expectancies. To our knowledge this is the first report of a DOE in a landmark-based spatial localization task and is one of only a few demonstrations that differential outcomes can enhance memory performance in normal functioning adults.
Sleep deprivation reduces vigilance or arousal levels, affecting the efficiency of certain cognitive functions such as learning and memory. Here we assessed whether the differential outcomes procedure (DOP), a learning procedure that has proved useful to ameliorate episodic memory deficits, can also improve memory performance in sleep-deprived participants. Photographs were presented as sample faces. A probe face was then presented for recognition after either short or long delays. In the differential outcomes condition a unique reinforcer followed correct responses. In the non-differential outcomes condition reinforcers were provided in a random manner. The results indicated that the DOP prevented the recognition memory to decrement during the long delay in the control group, replicating previous findings. The sleep-deprived group showed DOP benefits mainly with the short delay, when working memory could be affected by low arousal. These findings confirm that the DOP can overcome impaired recognition memory due to sleep deprivation conditions.
Although visual functions have been proposed to be enhanced in deaf individuals, empirical studies have not yet established clear evidence on this issue. The present study aimed to determine whether deaf children with diverse communication modes had superior visual memory and whether their performance was improved by the use of differential outcomes. Severely or profoundly deaf children who employed spoken Spanish, Spanish Sign Language (SSL), and both spoken Spanish and SSL modes of communication were tested in a delayed matching-to-sample task for visual working memory assessment. Hearing controls were used to compare performance. Participants were tested in two conditions, differential outcome and non-differential outcome conditions. Deaf groups with either oral or SSL modes of communication completed the task with less accuracy than bilingual and control hearing children. In addition, the performances of all groups improved through the use of differential outcomes.
Previous studies have demonstrated that discriminative learning is facilitated when a particular outcome is associated with each relation to be learned. When this training procedure is applied (the differential outcome procedure; DOP), learning is faster and more accurate than when the more common non-differential outcome procedure is used. This enhancement of accuracy and acquisition has been called the differential outcome effect (DOE). Our primary purpose in the present study was to explore the DOE in children born with great prematurity performing a discriminative learning task (Experiment 1) or a delayed visuospatial recognition task (Experiment 2). In Experiment 1, participants showed a faster learning and a better performance when differential outcomes were used. In Experiment 2, a significant DOE was also observed. That is, premature children performed the visuospatial recognition task better when they received differential outcomes following their correct responses. By contrast, the overall performance of full-term children was similar in both differential and non-differential conditions. These results are first to show that the DOP can enhance learning of conditional discriminations and recognition memory in children born prematurely with very low birth-weight.
It has been widely demonstrated that the differential outcomes procedure (DOP) facilitates both the learning of conditional relationships and the memory for the conditional stimuli in animal subjects. For conditional discriminations in humans, the DOP also produces an increase in the speed of acquisition and/or final accuracy. However, the potential facilitative effects of differential outcomes in human memory have not been fully assessed. In the present study, we aimed to test whether this procedure improves performance on a recognition memory task in healthy adults. Participants showed significantly better delayed face recognition when differential outcomes were used. This novel finding is discussed in the light of other studies on the differential outcomes effect (DOE) in both animals and humans, and implications for future research are presented.
The differential outcomes effect refers to the increase in accuracy obtained in discrimination tasks when rewards provided for correct responses vary according to the stimulus presented. The present research examined this effect in a sample of 63 university students (18-38 yrs old) discriminating multiple stimuli. A computer task was used to teach the meanings of 15 Japanese kanji characters, with both immediate (photos) and backup (lottery prizes) rewards following correct responses. Students were randomly allocated to one of three conditions: a differential condition (photos and prizes were uniquely associated with specific kanji), a partial differential condition (photos but not prizes were uniquely associated with specific kanji), and a nondifferential condition (photos and prizes were randomly associated with specific kanji). Participants in the differential condition learned the kanji meanings more quickly than those in the nondifferential condition. Accuracy in the partial differential condition was intermediate to, and not significantly different from, the other two conditions. These results extend the generality of the differential outcomes effect and have important practical implications.
Mode of access: World Wide Web. Title from document title page. Thesis (Ph. D.)--Louisiana State University, Baton Rouge, 2006.
Includes bibliographical references (leaves 48-55). Thesis (Ph.D.)--Western Michigan University, 2004.
In conditional discriminative choice learning, one learns the relations between discriminative/cue stimuli, associated choices, and their outcomes. When each correct cue-choice occurrence is followed by a cue-unique trial outcome (differential outcomes, DO, procedure), learning is faster and more accurate than when all correct cue-choice occurrences are followed by a common outcome (CO procedure)--differential outcomes effect (DOE). Superior DO performance is theorized to be mediated by the additional learning of cue-unique outcome expectations that "enrich" the prospective code available over the delay between cue and choice. We anticipated that such learned expectations comprise representations of expected outcomes. Here, we conducted an event-related functional MR imaging (fMRI) analysis of healthy adults who trained concurrently in two difficult but similar perceptual discrimination tasks under DO and CO procedures, respectively, and displayed the DOE. Control participants performed related tasks that differentially biased them towards delay-period retrospection versus prospection. Indeed, when differential outcomes were sensory-perceptual events (visual vs. auditory), delay-period expectations were experienced as sensory-specific imagery of the respectively expected outcome content, generated by sensory-specific cortices. Visual-specific imagery additionally activated stimulus-specific representations in prefrontal, lateral and medial frontal, fusiform and cerebellar regions, whereas auditory-specific imagery recruited claustrum/insula. Posterior parietal cortex (PPC), BA 39, was non-modality specific in mediating delay-period cue-unique outcome expectations. Greater hippocampal involvement in retrospection than prospection contrasted against the PPC's role in prospection. Time course analyses of hippocampal versus PPC responses suggest the DOE derives from an earlier transition from retrospection to prospection, which taps into long-term associative memory--more enduring.
The differential outcomes procedure (DOP) has proved useful to improve discrimination learning in both animals and humans. Here we adapted DOP to assess its utility to overcome the memory loss commonly associated with normal aging.
In a delayed matching-to-sample task, subjects were exposed to a man's face, and after a delay, they were required to decide if the previously seen face was within a set of six men's faces. For half the subjects, each sample face was paired with its own outcome (differential outcomes condition); outcomes were randomly arranged for the remaining half of subjects (non-differential condition). Either short (5 second) or long (30 second) delays were interposed between the sample and the comparison stimuli.
Results showed that relative to younger adults, older adults' performance decreased with the longer delay. However, the use of differential outcomes was able to reverse the detrimental effect of the increased delay in the elderly group, raising their performance to the level shown by younger adults.
These findings demonstrate, for the first time, that DOP can help elderly people overcome their memory limitations, and they draw attention to the potential of this procedure as a therapeutic technique.
This paper examines eight published reviews each reporting results from several related trials. Each review pools the results from the relevant trials in order to evaluate the efficacy of a certain treatment for a specified medical condition. These reviews lack consistent assessment of homogeneity of treatment effect before pooling. We discuss a random effects approach to combining evidence from a series of experiments comparing two treatments. This approach incorporates the heterogeneity of effects in the analysis of the overall treatment efficacy. The model can be extended to include relevant covariates which would reduce the heterogeneity and allow for more specific therapeutic recommendations. We suggest a simple noniterative procedure for characterizing the distribution of treatment effects in a series of studies.