Trail Making Task Performance in Inpatients with Anorexia Nervosa and Bulimia Nervosa

Disentangling cognitive flexibility: a model-based assessment of women with anorexia nervosa

Cognitive flexibility (CF) has been proposed as a potential trait marker in anorexia nervosa (AN), although findings have been inconsistent. To address this inconsistency, we applied a model that distinguishes between three subtypes of CF: task switching, switching sets, and stimulus-response mapping, which we then assessed using a paradigm-based task battery. The aim of the study was to investigate how AN is associated with these three CF subtypes. Thirty-three women with AN and 37 age- and education-matched controls performed a battery of computerized cognitive tasks to assess the three CF subtypes. Compared to the control group, individuals with AN exhibited poorer performance on the task switching and switching sets subtypes, as measured by response time switch cost, but not on the stimulus-response mapping subtype. No differences were found between the groups in response accuracy. Furthermore, switching sets as compared to the task switching and stimulus-response mapping subtypes was found to better explain the differences between the groups. These findings indicate a domain-specific impairment in CF among patients with AN, reflecting deficits observed in subtypes related to the disorder's characteristics, particularly that associated with visual perception. Therefore, CF impairment in AN should not be viewed dichotomously, but rather as a relative impairment that varies depending on the specific CF subtype.

Inpatient treatments for adults with anorexia nervosa: a systematic review of literature

PURPOSE

Anorexia nervosa (AN) is a mental disorder for which hospitalization is frequently needed in case of severe medical and psychiatric consequences. We aim to describe the state-of-the-art inpatient treatment of AN in real-world reports.

METHODS

A systematic review of the literature on the major medical databases, spanning from January 2011 to October 2023, was performed, using the keywords: "inpatient", "hospitalization" and "anorexia nervosa". Studies on pediatric populations and inpatients in residential facilities were excluded.

RESULTS

Twenty-seven studies (3501 subjects) were included, and nine themes related to the primary challenges faced in hospitalization settings were selected. About 81.48% of the studies detailed the clinical team, 51.85% cited the use of a psychotherapeutic model, 25.93% addressed motivation, 100% specified the treatment setting, 66.67% detailed nutrition and refeeding, 22.22% cited pharmacological therapy, 40.74% described admission or discharge criteria and 14.81% follow-up, and 51.85% used tests for assessment of the AN or psychopathology. Despite the factors defined by international guidelines, the data were not homogeneous and not adequately defined on admission/discharge criteria, pharmacological therapy, and motivation, while more comprehensive details were available for treatment settings, refeeding protocols, and psychometric assessments.

CONCLUSION

Though the heterogeneity among the included studies was considered, the existence of sparse criteria, objectives, and treatment modalities emerged, outlining a sometimes ambiguous report of hospitalization practices. Future studies must aim for a more comprehensive description of treatment approaches. This will enable uniform depictions of inpatient treatment, facilitating comparisons across different studies and establishing guidelines more grounded in scientific evidence.

LEVEL OF EVIDENCE

Level I, systematic review.

A meta-analysis of disordered eating and its association with self-criticism and self-compassion

OBJECTIVE

Future treatments for eating disorders (ED) need to be enhanced by targeting maintaining mechanisms. Literature suggests self-criticism and self-critical perfectionism act as key mechanisms exacerbating ED, and self-compassion protects against self-criticism. This meta-analysis examines associations between self-criticism and self-critical perfectionism on disordered eating (DE), and reviews how self-compassion and self-criticism relate to each other with respect to DE.

METHOD

Searches across three databases yielded 135 studies across 42,952 participants. Heterogeneity, publication bias, and quality assessments were analyzed. Moderation analyses between self-criticism measures, self-compassion measures, between clinical and nonclinical samples, and between cross-sectional and experimental studies were also conducted.

RESULTS

Random-effects models showed a medium positive link between self-criticism and DE (r = .37), and 10 subgroups pertaining to various measures of self-criticism utilized in literature showed small to large positive links with DE (r = .20-.52). Preliminary evidence also suggests negative relationships between self-compassion and DE (r = -.40 to -.43) and negative relationships between self-compassion and self-criticism (r = -.04 to -.88).

DISCUSSION

Greater levels of self-criticism is linked with greater levels of DE and reduced levels of self-compassion, suggesting a need to tackle self-criticism and nurture self-compassion in standard treatments for ED. Understanding these interactions better in conjunction with dismantling intervention studies can help develop more effective and efficient interventions targeting self-criticism and self-compassion for people with DE.

PUBLIC SIGNIFICANCE STATEMENT

Higher levels of self-criticism are linked with higher levels of DE and lower self-compassion. Self-compassion interventions could be more effective and efficient in reducing ED symptoms if self-criticism is tackled early in such treatments.

Investigating differences in cognitive flexibility, clinical perfectionism, and eating disorder-specific rumination across anorexia nervosa illness states

INTRODUCTION

Cognitive inflexibility, clinical perfectionism, and eating disorder (ED)-specific rumination are common characteristics reported in anorexia nervosa (AN) and may contribute to the maintenance of the illness. It is suggested that clinical perfectionism and rumination may mediate the relationship between cognitive flexibility and AN pathology; however, research to date has not investigated all these factors together. The aim of the current study was to explore the relationships between these factors and how they may relate to ED symptoms in AN.

METHODS

Participants included 15 women with a current diagnosis of AN, 12 women who had a past diagnosis of AN and were currently weight-restored, and 15 healthy controls (HCs).

RESULTS

The results revealed that participants with both acute and weight-restored AN self-reported poorer cognitive flexibility than HCs, but the groups did not differ in performance on objective assessments of cognitive flexibility. Participants with AN also reported significantly greater clinical perfectionism and ED-specific rumination than HC. A parallel mediation analysis found that ED-specific rumination mediated the relationship between subjective cognitive flexibility and ED symptoms. Further, subjective cognitive flexibility directly influenced ED symptoms. However, the mediation model was not significant for objective cognitive flexibility.

CONCLUSION

The findings of this study have implications for potential treatment barriers and factors which might contribute to the risk of relapse.

Temporal dynamics of cognitive flexibility in adolescents with anorexia nervosa: A high-density EEG study

Impairment in cognitive flexibility is a core symptom of anorexia nervosa (AN) and is associated with treatment resistance. Nevertheless, studies on the neural basis of cognitive flexibility in adolescent AN are rare. This study aimed to investigate brain networks underlying cognitive flexibility in adolescents with AN. To address this aim, participants performed a Dimensional Change Card Sorting task during high-density electroencephalography (EEG) recording. Anxiety was measured with the State-Trait Anxiety Inventory. Data were collected on 22 girls with AN and 23 controls. Evoked responses were investigated using global-spatial analysis. Adolescents with AN showed greater overall accuracy, fewer switch trial errors and reduced inverse efficiency switch cost relative to controls, although these effects disappeared after adjusting for trait and state anxiety. EEG results indicated augmented early visual orienting processing (P100) and subsequent impaired attentional mechanisms to task switching (P300b) in subjects with AN. During task switching, diminished activations in subjects with AN were identified in the posterior cingulate, calcarine sulcus and cerebellum, and task repetitions induced diminished activations in a network involving the medial prefrontal cortex, and several posterior regions, compared with controls. No significant associations were found between measures of cognitive flexibility and anxiety in the AN group. Findings of this study suggest atypical neural mechanisms underlying cognitive flexibility in adolescents with AN. More importantly, our findings suggest that different behavioural profiles in AN could relate to differences in anxiety levels. Future research should investigate the efficacy of cognitive training to rebalance brain networks of cognitive flexibility in AN.

Estimation of meal portions in bulimia nervosa compared to anorexia nervosa and healthy controls

PURPOSE

Bulimia nervosa (BN) and anorexia nervosa (AN) are potentially life-threatening eating disorders (ED) that primarily affect young people, mostly women. The central common pathology is linked to the relationship with food and with abnormalities in food intake. A previous study indicated that individuals with AN tend to overestimate food portion sizes compared to healthy controls (HC), but no study has investigated these patterns in BN, which was the objective of this study.

METHODS

Women with BN (27), AN (28), and HC (27) were asked to rate different meal portion sizes in two conditions: as if they were supposed to eat them (intent-to-eat condition) or in general (general condition). BN results were compared to HC and AN using mixed model analyses.

RESULTS

BN showed larger estimations compared to HC, while smaller estimations compared to AN. These differences were found mostly for intermediate portion sizes. No difference for conditions (intent-to-eat; general) was found between groups.

CONCLUSION

When estimating food portion sizes, individuals with BN seem to fall intermediately between HC and AN. ED symptoms in BN were most strongly associated with higher portion estimation. This might therefore reflect one aspect of the cognitive distortions typically seen also in AN. A therapeutic option could include the frequent visual exposure to increasing portions of food, what may serve to recalibrate visual perceptions of what a "normal-sized" portion of food looks like.

LEVEL OF EVIDENCE

Level II: Evidence obtained from well-designed controlled trials without randomization.

Understanding self-report and neurocognitive assessments of cognitive flexibility in people with and without lifetime anorexia nervosa

Objective: Anorexia nervosa (AN) is a serious eating disorder associated with several cognitive difficulties including poor cognitive flexibility (i.e. difficulties in effectively adapting to changes in the environment and/or changing task demands). AN research has primarily assessed cognitive flexibility using neurocognitive tests, and little is known about the differences or similarities between self-report and neurocognitive assessments of cognitive flexibility. This study investigated the relationship between self-report and neurocognitive assessments of cognitive flexibility in people with no history of an eating disorder (n = 207) and people with a self-reported lifetime diagnosis of AN (n = 19).Methods: Participants completed self-report and neurocognitive assessments of cognitive flexibility through an online study.Results: No significant correlations were found between self-report and neurocognitive assessments of cognitive flexibility for either group of the sample, suggesting that these assessments may evaluate different aspects of cognitive flexibility. Further, negative mood and self-reported eating disorder symptoms were found to significantly relate to self-reported cognitive flexibility, but were not associated with performance on neurocognitive tests of cognitive flexibility.Conclusions: To provide a comprehensive understanding of perceived and objective cognitive flexibility in AN, future research and clinical assessments should include both self-report and neurocognitive assessments.

Intact general and food-specific task-switching abilities in bulimia-spectrum eating disorders

OBJECTIVE

Prior work evaluating cognitive flexibility (i.e., the ability to alter behavior in response to environmental changes) in bulimia-spectrum eating disorders (BN-ED) has produced mixed findings, perhaps due to reliance on set-shifting paradigms that do not effectively isolate cognitive flexibility. Task-switching paradigms are more precise, but no study has examined task-switching in BN-ED. Further, no study has examined whether cognitive flexibility deficits in BN-ED are disorder-specific (e.g., confined to food-related responses). Thus, the present study re-evaluated cognitive flexibility in BN-ED using general and food-specific task-switching paradigms.

METHOD

Individuals with BN-ED (n = 28) and healthy controls (HC; n = 39) completed a cued color-shape switching task (CCSST) and a novel food-specific variation (FCCSST). We compared BN-ED and HC on switch costs (reflective of transient task-switching) and mix costs (reflective of maintenance of switching behavior).

RESULTS

Switch and mix costs were not significantly different between BN-ED and HC in terms of either accuracy or reaction time on the CCSST or FCCSST.

CONCLUSIONS

Findings suggest neither general nor food-specific cognitive flexibility is impaired in BN-ED. Rigidity in BN-ED (e.g., continued engagement in compensatory behaviors despite psychoeducation that these behaviors are ineffective for weight loss) may be a result of other neurocognitive impairments rather than cognitive flexibility deficits.

Cognitive flexibility and the risk of anorexia nervosa: An investigation using self-report and neurocognitive assessments

Impaired cognitive flexibility has been suggested as a risk factor for the development of anorexia nervosa (AN). The current study aimed to 1) investigate cognitive flexibility in people at various levels of risk of AN; and 2) compare people with a history of AN to people at different levels of risk of AN in cognitive flexibility. The sample comprised of 262 community participants (79% female) and 36 participants with a lifetime diagnosis of AN (97.2% female) aged between 18 and 64 years old. Participants completed self-report (the Depression Anxiety Stress Scale short-form version, the Eating Disorders Examination-Questionnaire, the Neuroticism Scale, and the Cognitive Flexibility Inventory) and neurocognitive (the Trail Making Test and the Wisconsin Card Sorting Test) assessments online to evaluate eating disorder symptoms, depression, neuroticism, and cognitive flexibility. Using a cluster analysis, participants were allocated into low-, medium-, and high-risk of AN groups (n = 88, 128, 46, and 36 respectively). Although high-risk participants self-reported significantly poorer cognitive flexibility than the other risk groups, performance on the neurocognitive tasks was similar across groups. Further, participants with lifetime AN reported significantly poorer cognitive flexibility than the low-risk group. People at high-risk of AN may perceive themselves to have poorer cognitive flexibility compared to those at a lower risk of AN. These results have implications for early identification of people at high-risk of AN.

Neural Correlates of Executive Functioning in Anorexia Nervosa and Obsessive-Compulsive Disorder

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) are commonly reported to co-occur and present with overlapping symptomatology. Executive functioning difficulties have been implicated in both mental health conditions. However, studies directly comparing these functions in AN and OCD are extremely limited. This review provides a synthesis of behavioral and neuroimaging research examining executive functioning in AN and OCD to bridge this gap in knowledge. We outline the similarities and differences in behavioral and neuroimaging findings between AN and OCD, focusing on set shifting, working memory, response inhibition, and response monitoring. This review aims to facilitate understanding of transdiagnostic correlates of executive functioning and highlights important considerations for future research. We also discuss the importance of examining both behavioral and neural markers when studying transdiagnostic correlates of executive functions.

Can Cognitive Flexibility and Clinical Perfectionism Be Used to Identify People with Anorexia Nervosa?

Poor cognitive flexibility and perfectionism are common features in anorexia nervosa (AN). The current study aimed to investigate cognitive flexibility and clinical perfectionism as potential predictors of AN. Twenty women with a current diagnosis of AN (M age = 28.25, SD = 7.62) and 170 community participants with no lifetime history of an eating disorder (M age = 29.23, SD = 9.88) took part in an online cross-sectional study that included self-report questionnaires of cognitive flexibility and clinical perfectionism. It was found that compared to the community sample, women with AN self-reported significantly poorer cognitive flexibility and significantly greater clinical perfectionism. In a regression model, clinical perfectionism (but not self-reported cognitive flexibility) significantly predicted group membership. The specificity and sensitivity of the model were high. These preliminary findings indicate that clinical perfectionism may represent a key feature of AN and may accurately discriminate between participants with and without AN, though more research is required.

Same room - different windows? A systematic review and meta-analysis of the relationship between self-report and neuropsychological tests of cognitive flexibility in healthy adults

Cognitive flexibility can be thought of as the ability to effectively adapt one's cognitive and behavioural strategies in response to changing task or environmental demands. To substantiate the common inference that self-report and neuropsychological tests of cognitive flexibility provide 'different windows into the same room', we undertook a systematic review and meta-analysis to determine whether self-report and neuropsychological tests of cognitive flexibility are related in healthy adults. Ten databases and relevant grey literature were searched from inception. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were adhered to. Twenty-one articles satisfied our inclusion criteria. A multi-level random-effects meta-analysis revealed no relationship (0.05, 95% CI = -0.00 to 0.10). Random-effects meta-analyses raised the possibility that the Cognitive Flexibility Scale and the Trail Making Test - part B (time) may be related (0.19, 95% CI = 0.06 to 0.31). We conclude that the relationship between self-report and neuropsychological tests of cognitive flexibility is not large enough to be considered convincing evidence for the two assessment approaches sharing construct validity. These results have clear implications for assessing and interpreting cognitive flexibility research and clinical practice.

Considerations for using the Wisconsin Card Sorting Test to assess cognitive flexibility

The Wisconsin Card Sorting Test (WCST) is a popular neurocognitive task used to assess cognitive flexibility, and aspects of executive functioning more broadly, in research and clinical practice. Despite its widespread use and the development of an updated WCST manual in 1993, confusion remains in the literature about how to score the WCST, and importantly, how to interpret the outcome variables as indicators of cognitive flexibility. This critical review provides an overview of the changes in the WCST, how existing scoring methods of the task differ, the key terminology and how these relate to the assessment of cognitive flexibility, and issues with the use of the WCST across the literature. In particular, this review focuses on the confusion between the terms 'perseverative responses' and 'perseverative errors' and the inconsistent scoring of these variables. To our knowledge, this critical review is the first of its kind to focus on the inherent issues surrounding the WCST when used as an assessment of cognitive flexibility. We provide recommendations to overcome these and other issues when using the WCST in future research and clinical practice.

Cognitive flexibility in acute anorexia nervosa and after recovery: A systematic review

Difficulties in cognitive flexibility-the ability to adapt effectively to changes in the environment and/or changing task demands-have been reported in anorexia nervosa (AN). However, findings are inconsistent across studies and it remains unclear which specific aspects of cognitive flexibility patients with AN may struggle with. This systematic review aimed to synthesise existing research on cognitive flexibility in AN and clarify differences between patients with acute AN, patients who are weight-restored and patients who are fully recovered from AN. Electronic databases were searched through to January 2020. 3,310 papers were screened and 70 papers were included in the final review. Although adults with acute AN performed worse in perceptual flexibility tasks and self-report measures compared to HCs, they did not exhibit deficits across all domains of cognitive flexibility. Adolescents with acute AN did not differ to HCs in performance on neurocognitive tasks despite self-reporting poorer cognitive flexibility. Overall, significant differences in cognitive flexibility between acute and recovered participants was not evident, though, the findings are limited by a modest number of studies. Recovered participants performed poorer than HCs in some neurocognitive measures, however, results were inconsistent across studies. These results have implications for the assessment of cognitive flexibility in AN and targeted treatment approaches.

A Neuropsychological Investigation of Perfectionism

Perfectionism entails a burdensome preoccupation with one's self-evaluation in the context of performance outcomes. Although perfectionism has been subject to extensive research, scant literature on its effect on cognitive functioning is available, let alone in nonclinical populations. The aim of the present study is to utilize a comprehensive neuropsychological battery to assess cognitive functions among college students with high and low levels of perfectionism. Participants were 98 college students who were screened for clinical status, completed a neuropsychological battery, and assessed for perfectionism and related symptomatology. Results revealed that the high negative perfectionism group had significantly higher levels of depression and stress compared to the low negative perfectionism group. However, no group differences were found across neuropsychological outcomes. Gradient differences on clinical outcome measures were found when three groups characterized by high adaptive, high maladaptive, and mixed perfectionism were compared. However, no differences were found on neuropsychological tests. These findings suggest that higher levels of negative perfectionism are associated with significant psychopathological burden, but with intact neuropsychological test performance. These results are important, particularly in the context of the need to identify and treat students struggling with high levels of perfectionism and related psychopathological burden, which can be overlooked given that they present with intact cognitive and academic performance.

Naturalistic follow-up of subjects affected with anorexia nervosa 8 years after multimodal treatment: Personality and psychopathology changes and predictors of outcome

Background:

Eating disorders (EDs) are serious mental illnesses of growing clinical and social impact. Despite their severity, there is still no satisfactory evidence-based treatment. Follow-up investigations are the most reliable studies to enlighten long-term outcome predictors and modifiers.

Methods:

In total, 59 subjects affected with anorexia nervosa were assessed 8 years after their admission into an outpatient multimodal treatment program for eating disorders. The follow-up changes in diagnostic criteria were compared with Chi-square test. Improved and not-improved subjects were compared. Clinical, personality and psychopathology features between T0 and T1 were compared with t-test for repeated measures. Correlation between T0 features and changes at T1 in personality and psychopathology features were assessed.

Results:

The rate of complete remission was 42%, an overall rate of 67.8% improved, a rate of 18.6% worsened. Concerning personality, a significant decrease of harm avoidance and increase in self-directedness were evidenced. Interoceptive awareness, drive for thinness, bulimia were significantly reduced at follow-up. Many T0 personality facets were related to personality and psychopathology improvement at follow-up.

Conclusion:

Multimodal treatment encompassing psychiatric, nutritional and psychological approaches is at the moment the most reliable approach for the treatment of moderate to severe anorexia nervosa with a discrete rate of improvement. Some personality and psychopathology characteristics may represent specific factors which favor resistance and impair improvement. Future approaches should consider the personalization of therapeutic approach according to these features.

General and Eating Disorder Specific Flexibility: Development and Validation of the Eating Disorder Flexibility Index (EDFLIX) Questionnaire

Findings from studies investigating cognitive flexibility in eating disorders (EDs) are inconsistent, and although neuropsychological tests are commonly used to measure these skills, they may not be particularly effective in predicting everyday functioning. Also, extant studies have largely focused on flexibility in anorexia nervosa (AN), with assessments targeting general rather than specific flexibility, and cognitive, rather than behavioral flexibility. Knowledge regarding ED specific flexibility and flexibility in bulimia nervosa (BN) and binge eating disorder (BED) is still scarce. The aim of this study was to develop and validate a novel measure assessing general and ED specific flexibility in a diagnostically diverse sample, and in healthy controls (HCs). A sample of 207 adult individuals with EDs (55% AN, 29% BN, 16% BED) and 288 HCs responded to an online, 51-item, pilot questionnaire on ED specific and general flexibility. In addition, participants completed the shift subscale from the Behavior Rating Inventory of Executive Function Adult version (BRIEF-A), and the Eating Disorder Diagnostic Scale (EDDS). A principal component analysis (PCA) in the clinical sample yielded a 36-item, three-factor solution capturing general flexibility, flexibility related to food and exercise, and flexibility concerning body shape and weight. Results showed that the measure had good to excellent internal consistency, and good convergent validity. A confirmatory factor analysis (CFA) using data from HCs revealed good fit indexes, supporting the original factor solution. A receiver operating characteristics analysis (ROC) demonstrated excellent accuracy in distinguishing scores from those with and without EDs. A cutoff score of 136 yielded the most balanced sensitivity and specificity. Significant differences in general and ED specific flexibility were found between individuals with and without EDs. Overall, HCs achieved the highest flexibility scores, followed by those with BED, BN, and AN. In sum this novel measure, the Eating Disorder Flexibility Index (EDFLIX) questionnaire, was found to be reliable and valid in the assessment of cognitive and behavioral flexibility, with results offering support for the conceptual distinction between general and ED related flexibility. The study also provides strong evidence for the discriminant validity of the EDFLIX with results revealing significant differences in flexibility in people with and without EDs. In addition, significant differences in flexibility also emerged when comparing diagnostic groups, indicating the utility of the assessment instrument for classification purposes.

Differences in set-shifting and central coherence across anorexia nervosa subtypes in children and adolescents

OBJECTIVE

Regarding executive functioning in anorexia nervosa (AN), little is known about differences between the restricting (AN-R) and binge eating/purging (AN-BP) subtypes. Especially for adolescents, there is sparse data. Hence, the current aim is to investigate differences in set-shifting, central coherence, and self-reported executive functioning across adolescent AN subtypes.

METHODS

Ninety AN-R, 21 AN-BP, and 63 controls completed an extensive assessment battery including neuropsychological tests for executive functioning and the self-report questionnaire Behavior Rating Inventory of Executive Functioning.

RESULTS

Patients with AN-R and AN-BP did not differ on neuropsychological measures, and both performed similarly to controls. Behavior Rating Inventory of Executive Functioning scores fell within the normal range with AN subtypes showing mostly comparable ratings. AN-BP patients scored higher on 2 composite indices and the "shift" subscale compared with AN-R.

CONCLUSIONS

The results suggest similar cognitive functioning in adolescent AN subtypes as well as healthy controls. However, more research is needed to draw more general conclusions.

Decision-Making Deficits Are Associated With Learning Impairments in Female College Students at High Risk for Anorexia Nervosa: Iowa Gambling Task and Prospect Valence Learning Model

This study investigated deficits in decision-making ability in female college students at high risk for anorexia nervosa (AN) using the Iowa Gambling Task (IGT) and the prospect valence learning (PVL) model. Based on scores on the Korean version of the Eating Attitude Test-26 (KEAT-26), participants were assigned to either the high risk for AN group (n = 42) or the control group (n = 43). The high risk for AN group exhibited significantly lower total net scores and block net scores on the third, fourth, and fifth blocks of the IGT than the control group did. The high risk for AN group selected cards significantly more often from the disadvantageous A and B decks and less often from the advantageous D deck than the control group did. In addition, the block net scores of the high risk for AN group did not differ across the five blocks, whereas those of the control group increased as the trials progressed. There was a significant negative correlation between IGT total net score and total score on the KEAT-26. The high risk for AN group had significantly lower values than the control group on the learning and response consistency parameters of the PVL model. These results indicate that female college students at high risk for AN have deficits in decision-making ability, and that these deficits are related to difficulties in remembering experience obtained from earlier trials and applying it to later trials. These difficulties further lead them to make decisions randomly.