Darrell A Worthy

• PhD.
• Professor (Associate) at Texas A&M University

This study investigated the assumptions of prototype and exemplar models of human category-learning, with a particular focus on the impact of category frequency. We used baseline and recency-weighted variants of prototype and exemplar models to examine the computational mechanisms underlying categorization decisions when one category was presented...

Eye-tracking is emerging as a tool for researchers to better understand cognition and behavior. However, it is possible that experiment participants adjust their behavior when they know their eyes are being tracked. This potential change would be considered a type of Hawthorne effect, in which participants alter their behavior in response to being...

Past research on reward-based decision making documents deviations from optimal behavior that suggest insufficient sensitivity to rare outcomes. This insensitivity to rare events has often led to suboptimal performance in gambling tasks. Participants tend to select options that provide frequent rewards, even though these same options sometimes give...

Exemplar-based categorization assumes that the categorization process is a comparison of the similarity of the current stimulus to all known exemplars in memory. The Generalized Context Model (GCM) proposed by Nosofsky (1984, 1986) has been shown to be effective in explaining and predicting human categorization behavior. However, little is known ab...

Real-world learning signals often come in the form of a continuous range of rewards or punishments, such as receiving more or less money or other reward. However, in laboratory studies, feedback used to examine how humans learn new categories has almost invariably been categorical in nature (i.e. Correct/Incorrect, or A/Not-A). Whether numerical or...

Real-world learning signals often come in the form of a continuous range of rewards or punishments, such as receiving more or less money or other reward. However, in laboratory studies, feedback used to examine how humans learn new categories has almost invariably been categorical in nature (i.e. Correct/Incorrect, or A/Not-A). Whether numerical or...

Research on the biological basis of reinforcement-learning has focused on how brain regions track expected value based on average reward. However, recent work suggests that humans are more attuned to reward frequency. Furthermore, older adults are less likely to use expected values to guide choice than younger adults. This raises the question of wh...

Many novel diseases are of zoonotic origin, likely including COVID-19. Describing diseases as originating from a diverse range of animals is known to increase risk perceptions and intentions to engage in preventative behaviors. However, it is also possible that communications depicting use of exotic animals as food sources may activate stereotypes...

Recent work in reinforcement learning has demonstrated a choice preference for an option that has a lower probability of reward (A) when paired with an alternative option that has a higher probability of reward (C), if A has been experienced more frequently than C (the frequency effect). This finding is critical as it is inconsistent with widesprea...

The ability to manipulate dopamine in vivo through non-invasive, reversible mechanisms has the potential to impact clinical, translational, and basic research. Recent PET studies have demonstrated increased dopamine release in the striatum after bifrontal transcranial direct current stimulation (tDCS). We sought to extend this work by examining whe...

People often fail to use base-rate information appropriately in decision-making. This is evident in the inverse base-rate effect, a phenomenon in which people tend to predict a rare outcome for a new and ambiguous combination of cues. While the effect was first reported in 1988, it has recently seen a renewed interest from researchers concerned wit...

Many emerging diseases (diseases that are increasing or likely to increase in prevalence) are zoonotic: that is, transmitted between animals and people. Behavioral science researchers have only begun to examine how health communications influence the public's response to zoonotic diseases. In this article, we discuss how cognitive research on induc...

Study Objectives The purpose of this study was to examine how rest-activity (RA) rhythm stability may be associated with white matter microstructure across the lifespan in healthy adults free of significant cardiovascular risk. Methods We analyzed multi-shell diffusion tensor images from 103 healthy young and older adults using tract-based spatial...

Given the increasing complexity of construction tasks, and the growing number of construction operations within confined workplaces, construction workers rely heavily on working memory. In this context, working memory is defined as the short-term and temporary storage of information related to near future events to ensure the seamless execution of...

We examined how well two popular RL models accounted for data in a task where participants could either select options or ‘explore’ options by seeing the rewards associated with each. The Delta model updates expected value (EV) by tracking each option’s average reward, while the Decay model updates EV by tracking each option’s cumulative reward. Pa...

Research on the biological basis of reinforcement-learning has focused on how brain regions track expected value based on average reward. However, recent work suggests that humans are more attuned to reward frequency. Furthermore, older adults are less likely to use expected values to guide choice than younger adults. This raises the question of wh...

Research on the biological basis of reinforcement-learning has focused on how brain regions track expected value based on average reward. However, recent work suggests that humans are more attuned to reward frequency. Furthermore, older adults are less likely to use expected values to guide choice than younger adults. This raises the question of wh...

Many emerging diseases (diseases that are increasing or likely to increase in prevalence) are zoonotic: that is, transmitted between animals and people. Behavioral science researchers have only begun to examine how health communications influence the public's response to zoonotic diseases. In this article, we discuss how cognitive research on induc...

Acute stress has been shown to influence reward sensitivity, feedback learning, and risk-taking during decision-making, primarily through activation of the hypothalamic pituitary axis (HPA). However, it is unclear how acute stress affects decision-making among choices that vary in their degree of uncertainty. To address this question, we conducted...

Highlights: Rest-activity rhythm stability was associated with greater white matter integrity in healthy young and older adults free of confounding health risk factors. Associated regions included the corpus callosum, anterior corona radiata, and superior longitudinal fasciculus.This relationship appears to be stable throughout the lifespan. Older...

Many novel diseases are of zoonotic origin, likely including COVID-19. Describing diseases as originating from diverse exotic animals can increase risk perceptions and protective avoidance behaviors, but may also activate stereotypes, increasing discriminatory behaviors and disease stigma. Data from the first several weeks of the US COVID-19 pandem...

Learning about the expected value of choice alternatives associated with reward is critical for adaptive behavior. Although human choice preferences are affected by the presentation frequency of reward-related alternatives, this may not be captured by some dominant models of value learning, such as the delta rule. In this study, we examined whether...

Learning about the expected value of choice alternatives associated with reward is critical for adaptive behavior. Although human choice preferences are affected by the presentation frequency of reward-related alternatives, this may not be captured by some dominant models of value learning, such as the delta rule. In this study, we examined whether...

The ability to manipulate dopamine in vivo through non-invasive, reversible mechanisms has the potential to impact clinical, translational, and basic research. A recent PET study demonstrated that a single session of prefrontal transcranial direct current stimulation (tDCS) increased striatal dopamine binding. We sought to extend this work by exami...

Reward-deficit models of addiction posit weaknesses in reward sensitivity to be promotive of substance dependence, whereas the externalizing spectrum model views substance problems as arising in large part from a general disinhibitory liability. In the current study we sought to integrate these perspectives by testing for separate and interactive a...

Acute stress influences reward-seeking tendencies and risky decision-making. However, it is unclear how acute stress influences decision-making in situations in which individuals must learn to either maximize long-term or immediate rewards from experience. Consequently, this study sought to investigate whether acute stress enhances salience of smal...

Extensive research has focused on gender differences in intertemporal choices made from description in which participants must choose from multiple options that are specified without ambiguity. However, there has been limited work examining gender differences in intertemporal choices made from experience in which the possible payoffs among choice a...

Background: Substance use problems are often characterized by dysregulation in reward sensitivity and inhibitory control. In line with this representation, the goal of this investigation was to determine how substance abuse tendencies among university students affect incentivized response inhibition. Additionally, this study examined whether stria...

Substance use has been linked to impairments in reward processing and decision-making, yet empirical research on the relationship between substance use and devaluation of reward in humans is limited. We report findings from two studies that tested whether individual differences in substance use behavior predicted reward learning strategies and deva...

Learning about reward and expected values of choice alternatives is critical for adaptive behavior. Although human choice is affected by the presentation frequency of reward-related alternatives, this is overlooked by some dominant models of value learning. For instance, the delta rule learns average rewards, whereas the decay rule learns cumulativ...

Extensive evidence suggests that people use base rate information inconsistently in decision making. A classic example is the inverse base rate effect (IBRE), whereby participants classify ambiguous stimuli sharing features of both common and rare categories as members of the rare category. Computational models of the IBRE have posited that it aris...

Number of trials where common and rare responses were made for each participant over the 24 ambiguous scene-object test trials.

The Delta and Decay rules are two learning rules used to update expected values in reinforcement learning (RL) models. The delta rule learns average rewards, whereas the decay rule learns cumulative rewards for each option. Participants learned to select between pairs of options that had reward probabilities of .65 (option A) versus .35 (option B)...

The Delta and Decay rules are two learning rules used to update expected values in reinforcement learning (RL) models. The delta rule learns average rewards, whereas the decay rule learns cumulative rewards for each option. Participants learned to select between pairs of options that had reward probabilities of .65 (option A) versus .35 (option B)...

Behavioral evidence suggests that people use base rate information ineffectively in category learning. A classic example is the inverse base rate effect, whereby participants classify ambiguous stimuli sharing features of both common and rare categories as members of the rare category. Explanations of this effect have focused primarily on selective...

The inverse base-rate effect (IBRE) describes an apparent irrationality in human decision making whereby people tend to ignore category base rates and choose rarer options when classifying ambiguous stimuli. According to associative learning theories, people choose rare categories for ambiguous stimuli because rare cues draw more attention. Alterna...

Decision-making is critical to everyday life. Here we ask: to what extent does music training benefit decision-making? Supported by strong associations between music training and enhanced cross-domain skills, we hypothesize that musicians may show decision-making advantages relative to non-musicians. Prior work has also argued for a “critical perio...

Gender differences in reward-based decision-making have been extensively researched, yet the mechanisms underlying these differences remain poorly understood. We sought to develop a mechanistic account of how men and women differ in their decision-making strategies. We examined gender differences in performance on the Iowa Gambling Task (IGT; Exper...

Dopaminergic genes play an important role in cognitive function. DRD2 and DARPP-32 dopamine receptor gene polymorphisms affect striatal dopamine binding potential, and the Val158Met single-nucleotide polymorphism of the COMT gene moderates dopamine availability in the pFC. Our study assesses the role of these gene polymorphisms on performance in tw...

This work aimed to investigate how one’s aspiration level is set in decision-making involving losses and how people respond when all alternatives appear to be below the aspiration level. We hypothesized that the zero point would serve as an ecological aspiration level where losses cause participants to focus on improvements in payoffs. In two exper...

Category learning results in increased discriminability along stimulus dimensions that are relevant for distinguishing between categories. Such heightened discriminability is thought to reflect a stretching of category representations along relevant dimensions. FMR adaptation is a measure of neural representation thought to be sensitive to represen...

We examined whether striatal dopamine moderates the impact of externalizing proneness (disinhibition) on reward-based decision making. Participants completed disinhibition and substance abuse subscales of the brief form Externalizing Spectrum Inventory and then performed a delay discounting task to assess preference for immediate rewards along with...

Older and younger adults performed a state-based decision-making task while undergoing functional MRI (fMRI). We proposed that younger adults would be more prone to base their decisions on expected value comparisons, but that older adults would be more reactive decision-makers who would act in response to recent changes in rewards or states, rather...

This article details a correction to the article: Steingroever, H. et al., (2015). Data from 617 Healthy Participants Performing the Iowa Gambling Task: A “Many Labs” Collaboration. Journal of Open Psychology Data. 3:e5. DOI: http://doi.org/10.5334/jopd.ak

Research distinguishes between a habitual, model-free system motivated toward immediately rewarding actions, and a goal-directed, model-based system motivated toward actions that improve future state. We examined the balance of processing in these two systems during state-based decision-making. We tested a regulatory fit hypothesis (Maddox & Markma...

Depressive symptomatology has been associated with alterations in decision-making, although conclusions have been mixed, with depressed individuals showing impairments in some contexts but advantages in others. The dopaminergic system may link depressive symptoms with decision-making performance. We assessed the role of striatal dopamine D2 recepto...

Decision making is rarely context-free, and often, both social information and non-social information are weighed into one's decisions. Incorporating information into a decision can be influenced by previous experiences. Ostracism has extensive effects, including taxing cognitive resources and increasing social monitoring. In decision making situat...

"Making an informed decision" implies that more information leads to better decisions, yet it may be the case that additional information biases decisions in a systematic and sometimes detrimental manner. In the present study, we examined the effect of additional information on older adults' decision-making using a task for which available rewards...

This data pool (N = 617) comes from 10 studies assessing performance of healthy participants (i.e., no known neurological impairments) on the Iowa gambling task (IGT)—a task measuring decision making under uncertainty in an experimental context. Participants completed a computerized version of the IGT consisting of 95 – 150 trials. The data consist...

Humans with seven or more repeats in exon III of the DRD4 gene (long DRD4 carriers) sometimes demonstrate impaired attention, as seen in attention-deficit hyperactivity disorder, and at other times demonstrate heightened attention, as seen in addictive behavior. Although the clinical effects of DRD4 are the focus of much work, this gene may not nec...

Gender differences in reward sensitivity and information processing were examined in two studies using a dynamic decision-making task. In Experiment 1, the optimal strategy involved forgoing an option that provided larger immediate rewards in favor of one yielding larger delayed rewards. In Experiment 2, the optimal strategy was to select the optio...

The purpose of the present study was to examine whether the Big Five personality factors could predict who thrives or chokes under pressure during decision-making. The effects of the Big Five personality factors on decision-making ability and performance under social (Experiment 1) and combined social and time pressure (Experiment 2) were examined...

Recent work suggests that older adults' decision-making behavior is highly affected by recent events. In the present work younger and older adults performed a two-choice task where one option provided a larger average reward, but there was a large amount of noise around the mean reward for each option which led to sharp improvements or declines in...

Depression is often characterized by attentional biases toward negative items and away from positive items, which likely affects reward and punishment processing. Recent work has reported that training attention away from negative stimuli reduced this bias and reduced depressive symptoms. However, the effect of attention training on subsequent lear...

We examined (1) whether people would be more responsive to the delayed consequences of their decisions when attempting to minimize losses than when attempting to maximize gains in a history-dependent decision-making task and (2) how trait self-control would moderate such an effect. In two experiments, participants performed a dynamic decision-makin...

In two experiments we examined the role of emotion, specifically worry, anxiety, and mood, on prospection during decision-making. Worry is a particularly relevant emotion to study in the context of prospection because high levels of worry may make individuals more aversive toward the uncertainty associated with the prospect of obtaining future impr...

Emerging evidence from decision neuroscience suggests that although younger and older adults show similar frontostriatal representations of reward magnitude, older adults often show deficits in feedback-driven reinforcement learning. In the present study, healthy adults completed reward-based tasks that did or did not depend on probabilistic learni...

Recent decision-making work has focused on a distinction between a habitual, model-free neural system that is motivated toward actions that lead directly to reward and a more computationally demanding goal-directed, model-based system that is motivated toward actions that improve one's future state. In this article, we examine how aging affects mot...

Models of human behavior in the Iowa Gambling Task (IGT) have played a pivotal role in accounting for behavioral differences during decision-making. One critical difference between models that have been used to account for behavior in the IGT is the inclusion or exclusion of the assumption that participants tend to persevere, or stay with the same...

We examined the relationship between pressure and age-related changes in decision-making using a task where currently available rewards depend upon the participant's previous history of choices. Optimal responding in this task requires the participant to learn how their current choices affect changes in the future rewards given for each option. Bui...

We examined the relationship between pressure and age-related changes in decision-making using a task for which currently available rewards depend on the participant's previous history of choices. Optimal responding in this task requires the participant to learn how his or her current choices affect changes in the future rewards given for each opti...

We examined the relationship between pressure and age-related changes in decision-making using a task where currently available rewards depend upon the participant's previous history of choices. Optimal responding in this task requires the participant to learn how their current choices affect changes in the future rewards given for each option. Bui...

We investigated whether narcissism affected dynamic decision-making performance in the presence and absence of misleading information. Performance was examined in a two-choice dynamic decision-making task where the optimal strategy was to forego an option providing larger immediate rewards in favor of an option that led to larger delayed rewards. I...

We examined how feedback delay and stimulus offset timing affected declarative, rule-based and procedural, information-integration category-learning. We predicted that small feedback delays of several hundred milliseconds would lead to the best information-integration learning based on a highly regarded neurobiological model of learning in the stri...

W.K. Estes often championed an approach to model development whereby an existing model was augmented by the addition of one or more free parameters to account for additional psychological mechanisms. Following this same approach we utilized Estes’ (1950) own augmented learning equations to improve the plausibility of a win-stay-lose-shift (WSLS) mo...

Prior research indicates that depressed individuals are less responsive to rewards and more sensitive to punishments than non-depressed individuals. This study examines decision-making under reward maximizing or punishment minimizing conditions among adults with low (n=47) or high (n=48) depression symptoms. We utilized a history-independent decisi...

Traumatic experiences have been shown to affect pain sensitivity and central processing. Our laboratory recently found that women reporting past trauma exhibit increased secondary hyperalgesia and spontaneous pain on the capsaicin test. The present study examined whether written emotional disclosure (WED) of trauma can alter the magnitude of this e...

The Iowa gambling task (IGT) has been used in numerous studies, often to examine decision-making performance in different clinical populations. Reinforcement learning (RL) models such as the expectancy valence (EV) model have often been used to characterize choice behavior in this work, and accordingly, parameter differences from these models have...

Individuals with depressive symptoms typically show deficits in decision-making. However, most work has emphasized decision-making under gain-maximization conditions. A gain-maximization framework may undermine decision-making when depressive symptoms are present because depressives are generally more sensitive to losses than gains. The present stu...

We examined the role of working memory (WM) in dynamic decision making by having participants perform decision-making tasks under single-task or dual-task conditions. In 2 experiments participants performed dynamic decision-making tasks in which they chose 1 of 2 options on each trial. The decreasing option always gave a larger immediate reward but...

We incorporated behavioral and computational modeling techniques to examine age-based differences in strategy use in two four-choice decision-making tasks. Healthy older (aged 60–82 years) and younger adults (aged 18–23 years) performed one of two decision-making tasks that differed in the degree to which rewards for each option depended on the cho...

In two experiments, younger and older adults performed decision-making tasks in which reward values available were either independent of or dependent on the previous sequence of choices made. The choice-independent task involved learning and exploiting the options that gave the highest rewards on each trial. In this task, the stability of the expec...

Cognitive psychologists have begun to address how motivational factors influence adults' performance on cognitive tasks. However, little research has examined how different motivational factors interact with one another to affect behavior across the lifespan. The current study examined how children perform on a classification task when placed in a...

We extend previous work examining the effects of pressure on category learning to the effects of pressure on categorization performance in highly trained individuals. After extensive training on either a rule-based or an information-integration classification task, half of the participants performed the same task on a fifth day while under pressure...

Previous research (Markman, Maddox, & Worthy, 2006) suggests that pressure leads to choking when one is learning to classify items on the basis of an explicit rule, but it leads to excelling when one is learning to classify items on the basis of an implicit strategy. In this article, we relate social pressure to regulatory focus theory. We propose...

Several models of choice compute the probability of selecting a given option by comparing the expected value (EV) of each option. However, a subtle but important difference between two common rules used to compute the action probability is often ignored. Specifically, one common rule type, the exponential rule, compares EVs via a difference operati...

This article examines the interface between motivation and choice. In category learning, a regulatory fit has been shown to increase exploration of alternative response strategies even when exploration is suboptimal. In the present study, promotion- and prevention-focused subjects performed a choice task that required them to choose from one of two...

Decrements in performance on cognitive tasks resulting from pressure to perform (i.e., choking) are thought to be caused by interference with the ability to use explicit strategies (the distraction theory). This view suggests that pressure should improve performance on tasks for which explicit strategies hamper performance. This hypothesis was test...

This study examined the effects of stimulus-feedback co-occurrence on rule-based and information-integration category learning. Rule-based categories are those for which a verbalizable rule is optimal. Information-integration categories are those for which the optimal rule is non-verbalizable. Participants performed a rule-based or an information-i...