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Discriminative learning and associative memory under the differential outcomes procedure is modulated by cognitive load
Abstract
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.
... This is easier to control for in the instrumental Stage 1 (e.g. through piloting). Low cognitive load [19] for the participants can be manipulated and evaluated in Stage 1this might manifest in few stimuli-response associations to be learned and be evaluated in terms of criterion performance (e.g. participants should achieve a high proportion of correct answers in the final blocks of the stage to demonstrate transferable learning). ...
... For example, in [4] we used a threshold of 0.8 correct performance for the final block (of 5 trials) as a measure of learning. Similarly, in [19], a threshold of 0.75 was used to as a criterion for learning. Validation of 1b) is rather more challenging. ...
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
... The DOP is particularly effective when learning is more taxing and the task is cognitively demanding (Estévez et al., 2001;Estévez et al., 2007;López-Crespo et al., 2009;Plaza et al., 2011). For instance, Fuentes et al. (2020) observed significant DOP effects for new memory associations, which were retained at 1 hour and 1 week follow ups, but only in the high cognitive load condition. On the other hand, if the task is too difficult there may not be sufficient correct responses for the unique expectancies to be established, and the DOP to work. ...
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.
Esta investigación pretendía explorar el impacto del Procedimiento de Consecuencias Diferenciales (PCD) en la estimulación de la Conciencia Fonológica y de la Velocidad de Denominación en alumnos prelectores. El estudio utilizó una muestra de 61 alumnos de edades comprendidas entre 5 y 5 años y 11 meses. Los resultados indicaron que los alumnos de Segundo nivel de Transición mostraron una mayor precisión a lo largo del estudio y en las tareas de recuerdo, en comparación con los alumnos del Primer nivel de Transición. Además, aquellos que recibieron consecuencias específicas en la condición “consecuencias diferenciales” aprendieron las asociaciones fonema-grafema más rápidamente que los de la condición “consecuencias no diferenciales”. Los resultados concuerdan con investigaciones anteriores que destacan el impacto positivo del PCD en la adquisición inicial de la lectura. En concreto, el estudio contribuye a este campo al demostrar la utilidad de este procedimiento como una estrategia eficaz para la enseñanza de la lectura, específicamente para estimular la Conciencia Fonológica. Se necesita más investigación para explorar los efectos a largo plazo y su posible aplicación en entornos educativos.
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.
In categorization tasks, two memory systems may be involved in the learning of categories: one explicit and rule-based system, and another implicit and procedure-based system. Learning of rule-base categories relies on some form of explicit reasoning, whereas procedural memory underlies information-integration category-learning tasks, in which performance is maximized only if information of two (or more) dimensions is integrated. The present study aimed at investigating the role of how feedback is administered, whether differential or non-differential, in procedural learning. An information-integration category-learning task was designed where the to-be-categorized stimuli differed in two dimensions. Participants were randomly assigned to two groups: one group received the reinforcers for correct categorizations differentially, one for each category (the differential outcomes procedure, DOP), and the other group received the reinforcers randomly (the non-differential outcomes procedure, NOP). The participants of the DOP group showed better procedural learning in the categorization task, compared to the NOP group. Moreover, analysis of learning strategies revealed that more participants developed more optimal strategies in the DOP group than in the NOP group. These results extend the benefits of the differential outcomes-based feedback to non-declarative memory tasks and help better understand the role of feedback in procedural learning.
It is well known that Alzheimer’s disease (AD), the most common form of dementia, is associated with deficits in cognitive processes including visual memory impairments. One technique that might be used to ameliorate these impairments is the differential outcomes procedure (DOP) that involves associating each to-be-remembered stimulus with a specific outcome.
Objective: Previous research has demonstrated that the DOP can be used to reduce or eliminate the learning and memory deficits associated with animal models of amnesia and dementia. Furthermore, this procedure has been shown to improve delayed facial recognition in healthy older adults as well as in patients diagnosed with AD. The main aim of the present study is twofold: to extend these findings to other types of visual stimulus and to investigate the effect of the DOP in memory retention in AD patients.
Method: Ten patients diagnosed with AD and 10 healthy controls participated in this study. The experiment included two phases. In the first one, they had to perform a delayed matching-to-sample task. In the second phase, participants performed a recognition memory task, designed to assess long-term retention, 1 h and 1 week after the training.
Results: Participants showed a better memory-based performance as well as a higher long-term retention of the information when trained under the differential outcomes condition, relative to the non-differential outcomes condition.
Conclusions: The DOP seems to be an effective, easy-to-implement, technique to enhance visual memory in AD patients.
In the present study we investigated the efficacy of the differential outcomes procedure (DOP) to improve visuospatial working memory in patients with Alzheimer’s disease and mild cognitive impairment (MCI). The DOP associates correct responses to the to-be-remember stimulus with unique outcomes. Eleven patients diagnosed with Alzheimer’s disease, 11 participants with MCI, and 17 healthy matched controls performed a spatial delayed memory task under the DOP and a control condition (non-differential outcomes –NOP-). We found that performance (terminal accuracy) was significantly better in the DOP condition relative to the NOP condition in all three groups of participants. AD patients performed worse, and took longer to benefit from the DOP. In line with previous animal and human research, we propose that the DOP activates brain structures and cognitive mechanisms that are less affected by healthy and pathological aging, optimizing in this way the function of the cognitive system.
Past research has consistently shown that episodic memory (EM) declines with adult age and, according to the associative-deficit hypothesis, the locus of this decline is binding difficulties. We investigated the importance of establishing and maintaining bindings in working memory (WM) for age differences in associative EM. In Experiment 1 we adapted the presentation rate of word pairs for each participant to achieve 67% correct responses during a WM test of bindings in young and older adults. EM for the pairs was tested thereafter in the same way as WM. Equating WM for bindings between young and older adults reduced, but did not fully eliminate, the associative EM deficit in the older adults. In Experiment 2 we varied the set size of word pairs in a WM test, retaining the mean presentation rates for each age group from Experiment 1. If a WM deficit at encoding causes the EM deficit in older adults, both WM and EM performance should decrease with increasing set size. Against this prediction, increasing set size did not affect EM. We conclude that reduced WM capacity does not cause the EM deficit of older adults. Rather, both WM and EM deficits are reflections of a common cause, which can be compensated for by longer encoding time.
It has recently been reported that the differential outcomes procedure (DOP) might be one of the therapeutical techniques focused at promoting autonomy in the elderly to deal with their medical issues. Molina et al. (2015) found that a group of healthy young adults improved their learning and long-term retention of six disorder/pill associations when each relationship to be learned was associated with a particular reinforcer (the differential outcomes condition) compared to when they were randomly administered (the non-differential outcomes condition). In the present study, we extend these findings to older adults who usually show difficulties to remember to take their medications as prescribed. Participants were asked to learn the association between three pills and the specific time at the day when they had to take each medication. Two memory tests were also performed 1 h and 1 week after completing the training phase. Results showed a faster learning of the task and long-term retention of the previously learned associations (pill/time of day) when differential outcomes were used. Furthermore, the older adults’ performance in the learning and memory phases did not differ from that of the younger adults in the DOP condition. These findings demonstrate that this procedure can help elderly people to ameliorate not only their learning, but also their long-term memory difficulties, suggesting the potential for the DOP to promote adherence to treatment in this population.
Memory for medical recommendations is a prerequisite for good adherence to treatment, and therefore to ameliorate the negative effects of the disease, a problem that mainly affects people with memory deficits. We conducted a simulated study to test the utility of a procedure (the differential outcomes procedure, DOP) that may improve adherence to treatment by increasing the patient’s learning and retention of medical recommendations regarding medication. The DOP requires the structure of a conditional discriminative learning task in which correct choice responses to specific stimulus–stimulus associations are reinforced with a particular reinforcer or outcome. In two experiments, participants had to learn and retain in their memory the pills that were associated with particular disorders. To assess whether the DOP improved long-term retention of the learned disorder/pill associations, participants were asked to perform two recognition memory tests, 1 h and 1 week after completing the learning phase. The results showed that compared with the standard non-differential outcomes procedure, the DOP produced better learning and long-term retention of the previously learned associations. These findings suggest that the DOP can be used as a useful complementary technique in intervention programs targeted at increasing adherence to clinical recommendations.
Previous research indicates that relative to younger adults, older adults show a larger decline in long-term memory (LTM) for associations than for the components that make up these associations. The purpose of the present study was to investigate whether we can impair associative memory performance in young adults by reducing their working memory (WM) resources, hence providing potential clues regarding the underlying causes of the associative memory deficit in older adults. With two experiments, we investigated whether we can reduce younger adults' long-term associative memory using secondary tasks in which either storage or processing WM loads were manipulated, while participants learned name-face pairs and then remembered the names, the faces, and the name-face associations. Results show that reducing either the storage or the processing resources of WM produced performance patterns of an associative long-term memory deficit in young adults. Furthermore, younger adults' associative memory deficit was a function of their performance on a working memory span task. These results indicate that one potential reason older adults have an associative deficit is a reduction in their WM resources but further research is needed to assess the mechanisms involved in age-related associative memory deficits.
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)
Adults with Prader-Willi syndrome learned the conditional relations necessary for the formation of two equivalence classes under four conditions: (a) nondifferential, nonedible outcomes; (b) nondifferential, edible outcomes; (c) differential, nonedible outcomes; and (d) differential, edible outcomes. Tests for transitive relations revealed superior performance when the two differential outcomes procedures, in which a distinct reinforcer was associated with each stimulus set, were used during teaching. Performance on test trials following nondifferential outcomes training was better when edible outcomes were used during teaching for 4 of the 5 participants. An enhancement of performance on the derived relations separated by two or three nodal stimuli was seen when a differential outcomes procedure was used to teach the baseline conditional relations.
It was hypothesized that age-related deficits in episodic memory for feature combinations (e.g., B. L. Chalfonte & M. K. Johnson, 1996) signal, in part, decrements in the efficacy of reflective component processes (e.g., M. K. Johnson, 1992) that support the short-term maintenance and manipulation of information during encoding (e.g., F. 1. M. Craik. R. G. Morris. & M. L. Gick, 1990; T. A. Salthouse, 1990). Consistent with this, age-related binding deficits in a working memory task were found in 2 experiments. Evidence for an age-related test load deficit was also found: Older adults had greater difficulty than young adults when tested on 2 features rather than 1, even when binding was not required. Thus, disruption of source memory in older adults may involve deficits in both encoding processes (binding deficits) and monitoring processes (difficulty accessing multiple features, evaluating them, or both).
Miller (1956) summarized evidence that people can remember about seven chunks in short-term memory (STM) tasks. However, that number was meant more as a rough estimate and a rhetorical device than as a real capacity limit. Others have since suggested that there is a more precise capacity limit, but that it is only three to five chunks. The present target article brings together a wide variety of data on capacity limits suggesting that the smaller capacity limit is real. Capacity limits will be useful in analyses of information processing only if the boundary conditions for observing them can be carefully described. Four basic conditions in which chunks can be identified and capacity limits can accordingly be observed are: (1) when information overload limits chunks to individual stimulus items, (2) when other steps are taken specifically to block the recording of stimulus items into larger chunks, (3) in performance discontinuities caused by the capacity limit, and (4) in various indirect effects of the capacity limit. Under these conditions, rehearsal and long-term memory cannot be used to combine stimulus items into chunks of an unknown size; nor can storage mechanisms that are not capacity-limited, such as sensory memory, allow the capacity-limited storage mechanism to be refilled during recall. A single, central capacity limit averaging about four chunks is implicated along with other, noncapacity-limited sources. The pure STM capacity limit expressed in chunks is distinguished from compound STM limits obtained when the number of separately held chunks is unclear. Reasons why pure capacity estimates fall within a narrow range are discussed and a capacity limit for the focus of attention is proposed.
The authors investigated the distinctiveness and interrelationships among visuospatial and verbal memory processes in short-term, working, and long-term memories in 345 adults. Beginning in the 20s, a continuous, regular decline occurs for processing-intensive tasks (e.g., speed of processing, working memory, and long-term memory), whereas verbal knowledge increases across the life span. There is little differentiation in the cognitive architecture of memory across the life span. Visuospatial and verbal working memory are distinct but highly interrelated systems with domain-specific short-term memory subsystems. In contrast to recent neuroimaging data, there is little evidence for dedifferentiation of function at the behavioral level in old compared with young adults. The authors conclude that efforts to connect behavioral and brain data yield a more complete understanding of the aging mind.
Two studies investigated the relationship between working memory capacity (WMC), adult age, and the resolution of conflict between familiarity and recollection in short-term recognition tasks. Experiment 1 showed a specific deficit of young adults with low WMC in rejecting intrusion probes (i.e., highly familiar probes) in a modified Sternberg task, which was similar to the deficit found in old adults in a parallel experiment (K. Oberauer, 2001). Experiment 2 generalized these results to 3 recognition paradigms (modified Sternberg, local recognition, and n back tasks). Old adults showed disproportional performance deficits on intrusion probes only in terms of reaction times, whereas young adults with low WMC showed them only in terms of errors. The generality of the effect across paradigms is more compatible with a deficit in content-context bindings subserving recollection than with a deficit in inhibition of irrelevant information in working memory. Structural equation models showed that WMC is related to the efficiency of recollection but not of familiarity.
In this meta-analysis, the authors evaluated recent suggestions that older adults' episodic memory impairments are partially due to a reduced ability to encode and retrieve associated/bound units of information. Results of 90 studies of episodic memory for both item and associative information in 3,197 young and 3,192 older adults provided support for the age-related associative/binding deficit suggestion, indicating a larger effect of age on memory for associative information than for item information. Moderators assessed included the type of associations, encoding instructions, materials, and test format. Results indicated an age-related associative deficit in memory for source, context, temporal order, spatial location, and item pairings, in both verbal and nonverbal material. An age-related associative deficit was quite pronounced under intentional learning instructions but was not clearly evident under incidental learning instructions. Finally, test format was also found to moderate the associative deficit, with older adults showing an associative/binding deficit when item memory was evaluated via recognition tests but not when item memory was evaluated via recall tests, in which case the age-related deficits were similar for item and associative information.
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.
An associative hypothesis to explain and predict older adults' deficient explicit episodic memory performance was outlined and tested. The hypothesis attributes a substantial part of older adults' deficient memory performance to their difficulty in merging unrelated attributes-units of an episode into a cohesive unit Although each of the components can be memorized to a reasonable degree, the associations that tie the attributes-units to each other grow weaker in old age. Four experiments are reported that provide (a) a converging validity to the hypothesis by demonstrating this associative deficit for both interitem relationships and intraitem relationships and (b) a discriminant validity to the hypothesis by contrasting and testing competing predictions made by the associative hypothesis and by alternative hypotheses. The implications of these results to older adults' episodic memory performance arc discussed.
Both acquisition and performance across delays are enhanced when each correct stimulus-response sequence in a conditional discrimination task is paired with a different reinforcing outcome, a procedure called differential outcomes (DO). It has been suggested that in the DO procedure, each discriminative stimulus comes to evoke an expectancy of a specific reward and this expectancy exerts stimulus control over choice behavior. Furthermore, expectancy control may reduce control by the discriminative stimulus itself under DO. In the study reported in this article, subjects under DO showed reduced ability to match based on the sample alone when expectancy could not be used to determine specific choices. The results generally support the contention that expectancy control is strong and sample stimulus control is weak under DO.
Visual working memory capacity is of great interest because it is strongly correlated with overall cognitive ability, can be understood at the level of neural circuits, and is easily measured. Recent studies have shown that capacity influences tasks ranging from saccade targeting to analogical reasoning. A debate has arisen over whether capacity is constrained by a limited number of discrete representations or by an infinitely divisible resource, but the empirical evidence and neural network models currently favor a discrete item limit. Capacity differs markedly across individuals and groups, and recent research indicates that some of these differences reflect true differences in storage capacity whereas others reflect variations in the ability to use memory capacity efficiently.
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)
Objective:
To provide a brief overview of the extent of medication nonadherence in the United States, its impact on patient health and health care costs, its causes, and possible strategies that health care practitioners can use to improve medication adherence.
Summary:
Medication use and health care costs have increased dramatically during the previous decade in the United States. Adherence to medication therapy often is a critical aspect of medical treatment, particularly the treatment of chronic conditions such as diabetes and hypertension. Despite the importance of adherence, medication nonadherence is a serious problem, with the World Health Organization noting that the average nonadherence rate is 50% among those with chronic illnesses. Consequences of nonadherence include worsening condition, increased comorbid diseases, increased health care costs, and death. Nonadherence results from many causes; therefore, no easy solutions exist. The first step to addressing nonadherence is to recognize that collaboration must occur between health care practitioners and patients to increase adherence, with the goal of achieving optimal health outcomes.
Conclusion:
The relationship between health care practitioners and patients and open, ongoing communication between the stakeholders are essential to combating medication nonadherence. Given their training and accessibility, pharmacists are well positioned to address nonadherence.
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 functional-neuroanatomical substrates for short-term retrospective versus prospective memory processing were examined in a delay task, in which associative choices were made conditionally based on the presenting discriminative/cue stimulus. Delay-period prospection could be of the intended choice and/or the expected response outcome, whereas delay-period retrospection would be of the just-presented cue stimulus. Previous results have shown that the spontaneous process of unique outcome prospection did not implicate the lateral prefrontal cortex (PFC) but instead implicated the lateral posterior parietal cortex (LPPC) in a modality-independent fashion (Mok et al., 2009). Spontaneous retrospection was more dependent on the medial temporal lobe (MTL). Nevertheless, it was anticipated that the more explicit process of prospecting an intended choice would implicate the lateral PFC. To verify this, Mok et al.'s data were further analyzed, with new control data. Healthy, young adults performed delayed discriminative choices under procedures that biased them toward different degrees of delay-period prospection: higher-using cue-unique, differential outcomes (DO); versus lower-using a non-unique, common outcome (CO), or unpredictable, non-differential outcomes (NDO). Experimental participants performed the DO versus CO procedures concurrently, while undergoing event-related functional magnetic resonance imaging (fMRI). Separately, control participants provided data for: the NDO condition; related comparison tasks, which biased them toward different degrees of delay-period retrospection; and null-event trials. Expectedly, the more explicit process of prospecting an intended associative choice implicated the lateral PFC, as part of and together with other components of the multiple-demand network. Comparisons against null-event trials indicated that the sustained delay activity observed in MTL and LPPC, respectively, was part of default brain activity. These results demonstrated that short-term retrospection and prospection may emerge without necessarily relying on working memory-specific brain networks. Furthermore, attention may not necessarily be recruited to realize working memory. When cognitive processes are spontaneously experienced, they may be facilitated by the default brain network.
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.
Aged (23 months) and young (3 months) rats were trained on an operant Matching-To-Position (MTP) task that had either (a) specific outcomes (reinforcers) correlated (differential groups), or (b) outcomes uncorrelated (nondifferential groups) for each correct sample-choice sequence. The traditional version of MTP uses a common outcome and is thought to assess spatial working memory. Aged rats are impaired on the traditional version of MTP. However, aged animals trained with the Differential Outcomes Procedure (DOP) did not display the typical age-related decline in spatial working memory. Differences in choice accuracy between old and young rats reached significance only if the subjects were trained with a nondifferential outcomes procedure (NOP)—similar to when a common outcome is used. These data demonstrate that employing behavioral procedures to tap intact cognitive functions is an effective means of enhancing spatial working memory in normal as well as aged subjects. © 1999 John Wiley & Sons, Inc. Dev Psychobiol 35: 318–327, 1999
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.
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.
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.
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.
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 outcomes procedure; DOP), learning is faster and better than when the typical common outcomes procedure or nondifferential outcomes (NDO) is used. Our primary purpose in the two experiments reported here was to assess the potential advantage of DOP in 5-year-old children using three different strategies of reinforcement in which (a) children received a reinforcer following a correct choice (" + "), (b) children lost a reinforcer following an incorrect choice (" - "), or (c) children received a reinforcer following a correct choice and lost one following an incorrect choice (" + / - "). In Experiment 1, we evaluated the effects of the presence of DOP and different types of reinforcement on learning and memory of a symbolic delayed matching-to-sample task using secondary and primary reinforcers. Experiment 2 was similar to the previous one except that only primary reinforcers were used. The results from these experiments indicated that, in general, children learned the task faster and showed higher performance and persistence of learning whenever differential outcomes were arranged independent of whether it was differential gain, loss, or combinations. A novel finding was that they performed the task better when they lost a reinforcer following an incorrect choice (type of training " - ") in both experiments. A further novel finding was that the advantage of the DOP over the nondifferential outcomes training increased in a retention test.
The capacity to seek and obtain rewards is essential for survival. Pavlovian conditioning is one mechanism by which organisms develop predictions about rewards and such anticipatory or expectancy states enable successful behavioral adaptations to environmental demands. Reward expectancies have both affective/motivational and discriminative properties that allow for the modulation of instrumental goal-directed behavior. Recent data provide evidence that different cognitive strategies (cue-outcome associations) and neural systems (amygdala) are used when subjects are trained under conditions that allow Pavlovian-induced reward expectancies to guide instrumental behavioral choices. Furthermore, it has been demonstrated that impairments typically observed in a number of brain-damaged models are alleviated or eliminated by embedding unique reward expectancies into learning/memory tasks. These results suggest that Pavlovian-induced reward expectancies can change both behavioral and brain processes.
Short-term memory storage can be divided into separate subsystems for verbal information and visual information, and recent studies have begun to delineate the neural substrates of these working-memory systems. Although the verbal storage system has been well characterized, the storage capacity of visual working memory has not yet been established for simple, suprathreshold features or for conjunctions of features. Here we demonstrate that it is possible to retain information about only four colours or orientations in visual working memory at one time. However, it is also possible to retain both the colour and the orientation of four objects, indicating that visual working memory stores integrated objects rather than individual features. Indeed, objects defined by a conjunction of four features can be retained in working memory just as well as single-feature objects, allowing sixteen individual features to be retained when distributed across four objects. Thus, the capacity of visual working memory must be understood in terms of integrated objects rather than individual features, which places significant constraints on cognitive and neurobiological models of the temporary storage of visual information.
In 1974, Baddeley and Hitch proposed a three-component model of working memory. Over the years, this has been successful in giving an integrated account not only of data from normal adults, but also neuropsychological, developmental and neuroimaging data. There are, however, a number of phenomena that are not readily captured by the original model. These are outlined here and a fourth component to the model, the episodic buffer, is proposed. It comprises a limited capacity system that provides temporary storage of information held in a multimodal code, which is capable of binding information from the subsidiary systems, and from long-term memory, into a unitary episodic representation. Conscious awareness is assumed to be the principal mode of retrieval from the buffer. The revised model differs from the old principally in focussing attention on the processes of integrating information, rather than on the isolation of the subsystems. In doing so, it provides a better basis for tackling the more complex aspects of executive control in working memory.
Correlating unique rewards with to-be-remembered events (the Differential Outcomes Procedure [DOP]) enhances learning and memory performance in a range of species. Recently, we have demonstrated that the DOP can be used to reduce or eliminate the learning and memory impairments associated with animal models of amnesia and dementia. This powerful phenomenon, the Differential Outcomes Effect (DOE), has led to the question: How does such a simple manipulation exert such dramatic influence on learning and memory performance? A revised two-process account of the DOE states that using the DOP results in the activation of reward expectancies through Pavlovian mechanisms. The use of unique reward expectancies alters the nature of cognitive processing used to solve discrimination tasks. The change in cognitive processing is represented by utilization of a different memory system than that commonly used to acquire and remember information when a Nondifferential Outcomes Procedure (NOP) is used. Using neurochemical manipulations, it has been demonstrated that different, potentially independent, brain systems modulate memory performance when subjects are trained with a NOP versus a DOP. This memory-based DOP/NOP distinction resembles other dissociative memory theories in which two psychological processes are purportedly served by distinct neurobiological mechanisms. In addition, such results have important ramifications for the treatment of memory disorders because they demonstrate that stimulus and behavioral manipulations, like drugs, can influence neurotransmitter functioning.
In previous studies, researchers have demonstrated that learning of symbolic relations is facilitated when a particular outcome is associated with each relation to be learned. In the present study, we extend this differential outcomes procedure to children and adults with Down syndrome who had to learn a symbolic conditional discrimination task. Participants showed a better terminal accuracy and a faster learning of the task when the alternative correct responses were each followed by unique different outcomes than when nondifferential outcomes were arranged. These findings confirm that the differential outcomes procedure can be a useful tool to ameliorate discriminative learning deficits and demonstrate the benefits of this procedure for people with Down syndrome.
The effect of tools and methods designed to enhance medication adherence that have been evaluated in randomized controlled trials was studied.
A literature search was performed with MEDLINE, International Pharmaceutical Abstracts, PsychLIT, ERIC, and EMBASE for the period from 1966 to December 2000. Only randomized, controlled trials with at least 10 subjects per intervention group were included.
Of 484 articles evaluated, only 61 met the criteria for the meta-analysis. Multiple interventions or study samples were identified in 23 of the articles. Each intervention was counted as a separate study, yielding 95 cohorts totaling 18,922 subjects. Of these subjects, 9,604 (51%) received interventions and 9,318 served as controls. Cohorts reported between 1990 and 1999 accounted for 53% of the sample; 56% of all cohorts were based in physician offices and 26% involved hypertensive patients. Behavioral interventions accounted for 41 cohorts (8,885 subjects), educational interventions for 22 cohorts (6,392 subjects), and combined interventions for 32 cohorts (3,645 subjects). Homogeneity of groupings and effect sizes (ESs) were calculated for each type of intervention. Overall, the data were not homogeneous, so conclusions could not be derived from the entire body of data. The educational intervention and combined intervention cohorts were nonhomogeneous (p < 0.001 and p < 0.01, respectively); however, the behavioral intervention cohort was homogeneous (Q = 42.48, d.f. = 40, p = 0.36). The overall ES for behavioral interventions was 0.07 (95% confidence interval [CI] = 0.04-0.09). There were no significant differences among the behavioral interventions. Educational interventions had an overall ES of 0.11 (95% CI = 0.06-0.15); there were no significant differences among the educational interventions. The overall ES of the combined interventions was 0.08 (95% CI = 0.04-0.12). When stratifying the combined intervention group by type of behavioral intervention, mail reminders had the largest impact (ES = 0.38).
Meta-analysis of studies of interventions to improve medication adherence revealed an increase in adherence of 4-11%. No single strategy appeared to be best.
The hippocampus appears to be critical for the formation of certain types of memories. Hippocampal-lesioned animals fail to exhibit some spatial, contextual, and relational associations. After aspiration lesions of the hippocampus and/or cortex, male rats were allowed to recover for three weeks before being trained on a matching-to-position task. The matching-to-position task was altered to influence the type of cognitive strategies a subject would use to solve the task. The main behavioral manipulation was the reinforcement contingency assignment: Use of a differential outcomes procedure (DOP) or a nondifferential outcomes procedure (NOP). The DOP involves correlating each to-be-remembered event with a distinct reward condition via Pavlovian trace conditioning, whereas the NOP results in random reward contingency. We found that hippocampal lesions did retard learning the matching rule, regardless of the reinforcement contingency assignment. However, when delay intervals were added to the task memory performance of subjects with hippocampal lesions was dramatically impaired--if subjects were not trained with the DOP. When subjects were trained with the DOP, the hippocampal lesion had a marginal effect on delayed memory performance. These findings demonstrate two important points regarding lesions of the hippocampus: (1) hippocampal lesions have a minimal effect on the on the ability of rats to use reward information to solve a delayed discrimination task; (2) rats with hippocampal lesions have the ability to learn about reward information using Pavlovian trace conditioning procedures.
The role of the reinforcer in instrumental discriminations has often been viewed as that of facilitating associative learning between a reinforced response and the discriminative stimulus that occasions it. The differential-outcome paradigm introduced by Trapold (1970), however, has provided compelling evidence that reinforcers are also part of what is learned in discrimination tasks. Specifically, when the availability of different reinforcing outcomes is signaled by different discriminative stimuli, the conditioned anticipation of those outcomes can provide another source of stimulus control over responding. This article reviews how such control develops and how it can be revealed, its impact on behavior, and different possible mechanisms that could mediate the behavioral effects. The main conclusion is that differential-outcome effects are almost entirely explicable in terms of the cue properties of outcome expectancies-namely, that conditioned expectancies acquire discriminative control just like any other discriminative or conditional stimulus in instrumental learning.
Previous studies have reported that the differential outcomes procedure enhances learning and memory in special populations with cognitive deficits (see Goeters, Blakely, & Poling, 19927.
Goeters , S. ,
Blakely , F. and
Poling , A. 1992. The differential outcomes effect. The Psychological Record, 42: 389–411. View all references, for a review). In the present study we extend these findings to healthy adults who were asked to discriminate between the symbols “ > ” and “ < ” in mathematical statements. In Experiment 1, the performance of participants who showed difficulties in discriminating between these symbols was better (shorter response times) for the differential outcomes condition than for the nondifferential outcomes condition. In Experiment 2, the difficulty of the task was increased by using signed decimal numbers. Similar to Experiment 1, participants who initially had difficulties in discriminating between the symbols showed better performance (higher accuracy) for the differential outcomes condition than for the nondifferential outcomes condition, but only when both numbers were negative. These findings suggest that the differential outcomes procedure can be used to improve performance of challenged healthy adults on discrimination tasks with mathematical symbols and relations.
Adherencia al tratamiento farmacológico
- Bonafont
Bonafont, X., & Costa, J. (2004). Adherencia al tratamiento farmacológico. Butlletí
D'Informació Terapèutica, 16(3), 9-14.
The second learning process in instrumental learning
- Trapold
Trapold, M. A., & Overmier, J. B. (1972). The second learning process in instrumental
learning. In A. H. Black, & W. F. Prokasy (Eds.). Classical conditioning: Current research
and theory (pp. 427-452). New York: Appleton-Century-Crofts.