Eldad Yechiam

Using Cognitive Models to Map Relations Between Neuropsychological Disorders and Human Decision-Making Deficits

Findings from a complex decision-making task (the Iowa gambling task) show that individuals with neuropsychological disorders are characterized by decision-making deficits that lead to maladaptive risk-taking behavior. This article describes a cognitive model that distills performance in this task into three different underlying psychological components: the relative impact of rewards and punishments on evaluations of options, the rate that the contingent payoffs are learned, and the consistency between learning and responding. Findings from 10 studies are organized by distilling the observed decision deficits into the three basic components and locating the neuropsychological disorders in this component space. The results reveal a cluster of populations characterized by making risky choices despite high attention to losses, perhaps because of difficulties in creating emotive representations. These findings demonstrate the potential contribution of cognitive models in building bridges between neuroscience and behavior.

Iowa Gambling Task in schizophrenia: A review and new data in patients with schizophrenia and co-occurring cannabis use disorders

BACKGROUND We reviewed previous studies comparing schizophrenia patients and healthy subjects for performance on the Iowa Gambling Task (IGT) (a laboratory task designed to measure emotion-based decision-making), and found mixed results. We hypothesize that deficits in IGT performance in schizophrenia may be more specifically related to concurrent substance use disorders. To test this hypothesis, we compared schizophrenia patients with (SCZ((+))) or without (SCZ((-))) cannabis use disorders, to healthy subjects, on measures of cognition and IGT performance. METHODS A comprehensive battery of cognitive tests and the IGT were administered to three groups of subjects: (1) 13 subjects with DSM-IV diagnosis of schizophrenia and no concurrent substance use disorders (mean age: 28+/-12 (SD); 54% males); (2) 14 subjects with schizophrenia and concurrent cannabis use disorders (mean age: 29+/-9 (SD); 71% males); and (3) 20 healthy subjects (mean age 33+/-10 (SD); 60% males). RESULTS Compared to the healthy group, both schizophrenia groups were cognitively more impaired, and did worse on IGT performance. There were no differences between SCZ((+)) and SCZ((-)) patients on most of the cognitive tests, and IGT performance. CONCLUSIONS Schizophrenia patients show widespread impairments in several cognitive domains and emotion-based decision-making. These results are consistent with the evidence that schizophrenia reflects a dorsolateral and orbitofrontal/ventromedial prefrontal cortex dysfunction. More intriguing, it appears that the concurrent abuse of cannabis has no compounding effects on cognition, as well as emotion/affect-based decision-making.

Comparison of basic assumptions embedded in learning models for experience-based decision making

The present study examined basic assumptions embedded in learning models for predicting behavior in decisions based on experience. In such decisions, the probabilities and payoffs are initially unknown and are learned from repeated choice with payoff feedback. We examined combinations of two rules for updating past experience with new payoff feedback and of two choice rule assumptions for mapping experience onto choices. The combination of these assumptions produced four classes of models that were systematically compared. Two methods were employed to evaluate the success of learning models for approximating players’ choices: One was based on estimating parameters from each person’s data to maximize the prediction of choices one step ahead, conditioned by the observed past history of feedback. The second was based on making a priori predictions for the entire sequence of choices using parameters estimated from a separate experiment. The results indicated the advantage of a class of models incorporating decay of previous experience, whereas the ranking of choice rules depended on the evaluation method used.

The Role of Personal Experience in Contributing to Different Patterns of Response to Rare Terrorist Attacks

An examination of the behavioral effect of repeated terrorist attacks reveals that local residents (of the attacked area) appear to be much less sensitive to this risk than international tourists. Furthermore, the limited sensitivity on the part of local residents seems to diminish with time, even when the attacks continue. An experimental study shows a similar pattern in a laboratory experiment that focuses on a basic decision task: when making a single decision based on a description of the problem, people tend to be more risk averse. Personal experience with the problem reduces this sensitivity. These results highlight an interesting relationship between basic decision-making research and the study of the response to traumatic events.

Emotion-based decision-making in healthy subjects: short-term effects of reducing dopamine levels

IntroductionConverging evidences from animal and human studies suggest that addiction is associated with dopaminergic dysfunction in brain reward circuits. So far, it is unclear what aspects of addictive behaviors are related to a dopaminergic dysfunction.DiscussionWe hypothesize that a decrease in dopaminergic activity impairs emotion-based decision-making. To demonstrate this hypothesis, we investigated the effects of a decrease in dopaminergic activity on the performance of an emotion-based decision-making task, the Iowa gambling task (IGT), in 11 healthy human subjects.Materials and methodsWe used a double-blind, placebo-controlled, within-subject design to examine the effect of a mixture containing the branched-chain amino acids (BCAA) valine, isoleucine and leucine on prolactin, IGT performance, perceptual competency and visual aspects of visuospatial working memory, visual attention and working memory, and verbal memory. The expectancy-valence model was used to determine the relative contributions of distinct IGT components (attention to past outcomes, relative weight of wins and losses, and choice strategies) in the decision-making process.Observations and resultsCompared to placebo, the BCAA mixture increased prolactin levels and impaired IGT performance. BCAA administration interfered with a particular component process of decision-making related to attention to more recent events as compared to more distant events. There were no differences between placebo and BCAA conditions for other aspects of cognition. Our results suggest a direct link between a reduced dopaminergic activity and poor emotion-based decision-making characterized by shortsightedness, and thus difficulties resisting short-term reward, despite long-term negative consequences. These findings have implications for behavioral and pharmacological interventions targeting impaired emotion-based decision-making in addictive disorders.

Losses as modulators of attention: Review and analysis of the unique effects of losses over gains.

It has been shown that in certain situations losses exert a stronger effect on behavior than respective gains, and this has been commonly explained by the argument that losses are given more weight in peoples decisions than respective gains. However, although much is understood about the effect of losses on cognitive processes and behavior, 2 major inconsistencies remain. First, recent empirical evidence fails to demonstrate that people avoid incentive structures that carry equivalent gains and losses. Second, findings in experience-based decision tasks indicate that following losses, increased arousal is observed simultaneously with no behavioral loss aversion. To account for these findings, we developed an attention-allocation model as a comprehensive framework for the effect of losses. According to this model losses increase on-task attention, thereby enhancing the sensitivity to the reinforcement structure. In the current article we examine whether this model can account for a broad range of empirical phenomena involving losses. We show that as predicted by the attentional model, asymmetric effects of losses on behavior emerge where gains and losses are presented separately but not concurrently. Yet, even in the absence of loss aversion, losses have distinct effects on performance, arousal, frontal cortical activation, and behavioral consistency. The attentional model of losses thus explains some of the main inconsistencies in previous studies of the effect of losses.

Decision-making impairments in adolescents with early-onset schizophrenia

Adolescence is a time of vulnerability for risk-taking behaviors. This is particularly true of adolescents with schizophrenia who present with high rates of substance use as compared to the general population. Using the Iowa Gambling Task (IGT), the authors compared decision-making processes in adolescents with early-onset schizophrenia (onset of psychosis by age 18) to that of healthy volunteers. Fifteen adolescents with schizophrenia (aged 12-21 years) and 25 demographically similar healthy volunteers were administered the IGT. Overall, adolescents with schizophrenia performed significantly worse on the IGT than healthy adolescents as measured by a significant group by block interaction. Post-hoc testing revealed that adolescents with schizophrenia performed more poorly than healthy adolescents during the last two blocks of the task. Mathematical modeling further indicated that adolescents with schizophrenia allocated significantly more attention to monetary gains than losses encountered during the task, suggesting a hypersensitivity to rewards and relative insensitivity to future consequences. This is similar to what has been reported for adults with externalizing forms of psychopathology, such as those who abuse substances. These findings have potential implications for understanding the increased vulnerability for the development of substance abuse in adolescents with schizophrenia.

Neurocognitive deficits related to poor decision making in people behind bars.

Using a novel quantitative model of repeated choice behavior, we investigated the cognitive processes of criminal offenders incarcerated for various crimes. Eighty-one criminals, including violent offenders, drug and sex offenders, drivers operating a vehicle while impaired, and 18 matched controls were tested. The results were also contrasted with those obtained from neurological patients with focal brain lesions in the orbitofrontal cortex and from drug abusers. Participants performed the computerized version of the Iowa gambling task (Bechara, Damasio, Damasio, & Anderson, 1994), and the results were decomposed into specific component processes, using the expectancy valence model (Busemeyer & Stout, 2002). The findings indicated that whereas all the criminal groups tended to select disadvantageously, the cognitive profiles exhibited by different groups were considerably different. Certain subpopulations—most significantly, drug and sex offenders—overweighted potential gains as compared with losses, similar to chronic cocaine abusers. In contrast, assault/murder criminals tended to make less consistent choices and to focus on immediate outcomes and, in these respects, were more similar to patients with orbitofrontal damage. The present cognitive model provides a novel way for building a bridge between cognitive neuroscience and complex human behaviors.

Motivational processes and autonomic responsivity in Asperger's disorder: evidence from the Iowa Gambling Task.

Aspergers disorder (ASP), like other autism spectrum disorders, is associated with altered responsiveness to social stimuli. This study investigated learning and responsiveness to nonsocial, but motivational, stimuli in ASP. We examined choice behavior and galvanic skin conductance responses (SCRs) during the Iowa Gambling Task (IGT; Bechara et al., 1994) in 15 adolescents and young adults with ASP and 14 comparison subjects. We examined aspects of learning, attention to wins and losses, and response style with a formal cognitive model, the Expectancy-Valence Learning model (Busemeyer & Stout, 2002). The ASP group did not differ from the comparison group in proportions of selections from advantageous decks. However, ASP participants showed a distinct pattern of selection characterized by frequent shifts between the four IGT decks, whereas comparison participants developed clear deck preferences. SCR results showed some evidence of reduced responsiveness in the ASP group during the IGT. Results from the cognitive model indicated that, in contrast to the comparison group, the ASP groups selections were less consistent with the motivational significance they assigned to decks. Findings are discussed in the context of the neurobiological substrates associated with IGT performance.

Non-specific effects of methylphenidate (Ritalin) on cognitive ability and decision-making of ADHD and healthy adults

IntroductionThe effect of a single dose of methylphenidate (MPH) on cognitive measures and decision-making processes was assessed in a sample of adults with ADHD and in a control sample.MethodsThirty-two adults satisfying DSM-IV criteria for ADHD and 26 healthy controls performed several cognitive tasks. Half of the participants received MPH prior to performing the tasks, and the other half received placebo in a randomized, double-blind manner.ResultsThe average digit-span test score was higher in the groups receiving MPH compared to the groups receiving placebo, while diagnosis did not have an effect upon scores. In decision-making tasks, however, MPH did not have an effect upon performance, whereas in one of the tasks the average proportion of risky choices was higher in ADHD adults compared to controls.ConclusionOur data therefore demonstrates that (a) MPH is capable of enhancing specific aspects of cognitive performance and (b) this enhancement is not specific to ADHD.