Objectives: The aim of the present study was to investigate “Proactive-Adjustment hypothesis” (PA) during the Stop Signal Task (SST). The PA is implied in the highly inconsistent literature, and it deals with the role of response inhibition (RI) in obsessive-compulsive disorder (OCD). This hypothesis assumed that participants would balance stopping and going by adjusting the response threshold (RT) in the go task. We verified whether the PA strategy was also implemented in our clinical group. Methods: To reach this goal, we analyzed SST performances in a group of 36 patients with OCD and 36 healthy controls (HCs). To identify different participants’ behaviors during the task, without preconceived notions regarding the diagnosis, we performed a cluster analysis. Furthermore, we analyzed the influence of drug therapy and we investigated whether the rule and reversal acquisition investigated with the Intra-Extra Dimensional Set Shift, differed in the two clusters. Results: We did not find any difference relative to the number of patients with OCD and HCs included in the two clusters. Furthermore, we found that only Not Proactive participants performed the task as fast as possible, while Proactive participants consistently slowed down their RTs and showed a lower number of Direction Errors, higher Stop Signal Delay, and worse cognitive flexibility. Conclusions: Our results show that among patients with OCD the use of PA is changeable and does not differ from HCs. This finding supports the idea that the RI heterogeneity concerning patients with OCD could be related to PA. (JINS, 2018, 24, 1–12)

We assessed language switch and mixing costs in a language-general semantic categorization task and examined how these costs relate to general inhibition and set shifting capacities. The participants were 51 native Finnish subjects with English as L2. The results showed significant symmetric language switch costs and, unexpectedly, a mixing advantage in L2: reaction times were faster in the mixed language block than in the single language block. The interactions with the general executive functions showed no consistent overall pattern. We argue that the L2 mixing advantage stems from statistical facilitation in line with a horse race model, or from opportunistic planning as suggested by the Adaptive Control hypothesis. We argue that the results overall indicate that lexical access in language reception is non-selective.

Difficulties in set-shifting are commonly reported in both autism spectrum disorder (ASD) and anorexia nervosa (AN) populations. Despite this, it is not known whether this cognitive profile persists across different ages, or whether the profiles seen in ASD and AN are comparable. This systematic review and meta-analyses aimed to compare the set-shifting profiles, as measured by the Wisconsin Card Sorting Test (WCST) in adults and younger people with either ASD or AN, relative to healthy controls (HCs) and to statistically compare performance on the WCST between ASD and AN. In all, 24 studies on ASD and 22 studies on AN were identified. In ASD, there were significant differences between the clinical group and HCs, with the ASD group making significantly more perseverative errors, indicating greater difficulty in set-shifting [pooled effect size of d = 0.67, 95% confidence interval (CI) 0.53–0.81, p ⩽ 0.001]. This effect was consistent across the age span. For AN studies, there was a significant difference between adults with AN and HCs (d = 0.52, 95% CI 0.36–0.68, p ⩽ 0.001) but a non-significant effect in child studies (d = 0.25, 95% CI −0.05 to 0.55, z = 1.66, p = 0.096). Meta-regression indicated no effect of diagnosis (AN or ASD) on performance in adult studies but there was a non-significant trend (p = 0.053) towards children with ASD performing worse than children with AN. While difficulties with set-shifting appear to be stable in ASD, there may be differences between children and adults with AN, which warrant further investigation.

Perseveration is a core symptom of schizophrenia, the cause, however, is unknown. It has been shown that for people with frontal lobe lesions, perseveration can be explained with a set-maintenance problem. Perseveration in Parkinson's disease can be explained with problems shifting from one set to another without cues (set-shifting). These disorders can be distinguished using a two-choice task and the Wisconsin Card Sorting Test, that is analysed in phases. Analogs of these tests can be used in animal research. By adding an animal part to the human research, more insight can be gained into the role of specific brain areas in set-maintenance and set-shifting.

Research with patients suffering from Parkinson's disease and frontal lobe lesions has shown that disturbances in the fronto-striatal loops in the brain can cause perseveration. Perseveration is a core symptom of schizophrenia, yet the cause is not known. For schizophrenic patients disorders of many parts of the fronto-striatal loops are found, for example disturbances of the prefrontal cortex and the striatum. Perseveration in schizophrenia can be explained with set-maintenance problems, related to dysfunction of the prefrontal cortex, or with set-shifting problems that are related to disorders in the striatum. These set-maintenance and set-shifting problems can be distinguished with neuropsychological tests. Regarding the bloodflow patterns for the different subtypes of schizophrenia three problems are expected as explanations for perseveration: set-maintenance problems concerning abstract information, set-maintenance problems shifting between stimuli and enhanced set-shifting with cues.

This review describes a research program aimed at evaluating the validity and specificity of the Wisconsin Card Sorting Test (WCST), one of the most widely used tests of prefrontal function in clinical and experimental neuropsychology. In spite of its extensive use, voices of caution have arisen against the use of WCST scores as direct markers of prefrontal damage or dysfunction. Adopting a cognitive neuroscience approach, the present research program integrates behavioral, physiological, and anatomical information to investigate the cognitive and neural mechanisms behind WCST performance. The results show that WCST performance evokes conspicuous physiological changes over frontal as well as posterior brain regions. Moreover, WCST scores confound very heterogeneous cognitive and neural processes. This confounding effect may have led many authors to overlook the relative importance of certain dysfunctional states such as those indexed by random errors. These findings strongly suggest that WCST scores cannot be regarded as valid nor specific markers of prefrontal lobe function. However, they do provide some relevant clues to update our current knowledge about prefrontal function. In the long run, the integrative approach of cognitive neuroscience may help us design and develop more valid and sensitive tools for neuropsychological assessment.

The ability to switch rapidly and fluidly between tasks is an important component of many everyday activities. In this study, we used a predictable, externally cued task-switching paradigm to investigate executive control processes in individuals with mild cognitive impairment (MCI). Participants were 26 individuals with amnestic MCI and 26 healthy older adult (OA) controls. In the mixed-task trials, participants switched between classifying whether a digit was odd/even or a letter was a consonant/vowel on every fourth trial. In the single-task trials, participants completed only the digit task or letter task throughout the entire block. Task switching costs were decomposed into nonswitch costs, which reflect the dual nature of the task, and switch costs, which reflect set-shifting abilities. The results revealed that the MCI group was not affected more than the healthy OAs by the requirement of keeping two tasks sets active in working memory (nonswitch costs). In contrast, the cost of switching between the two tasks was significantly greater for the MCI group compared with the OA controls (switch costs). Future research is needed to better understand the nature and implications for daily living of the greater switch costs found for individuals with MCI. (JINS, 2009, 15, 103–111.)

This study evaluated cognitive set-shifting in 12 patients with focal lesions in the lateral prefrontal cortex (LPC) by examining their performance on the Trail Making Test from the Delis-Kaplan Executive Function System (D-KEFS). Patients with LPC lesions performed significantly worse than controls on the D-KEFS Trail Making Test on the Letter Sequencing, Number-Letter Switching (set-shifting), and Motor Speed conditions. Patients with LPC lesions performed significantly more slowly on the Number-Letter Switching condition even after controlling for performance on the four baseline conditions of the test. In addition, patients with LPC lesions exhibited significantly elevated error rates on the Number-Letter Switching condition. Results suggest that LPC lesions can lead to impaired cognitive set-shifting on a visual-motor sequencing task. (JINS, 2007, 13, 704–709.)

The aim of this study was to determine if there are differences in cognitive flexibility in anorexia nervosa and bulimia nervosa. Fifty-three patients with an eating disorder (34 with anorexia nervosa and 19 with bulimia nervosa) and 35 healthy controls participated in the study. A battery of neuropsychological tests for cognitive flexibility was used, including Trail Making B, the Brixton Test, Verbal Fluency, the Haptic Illusion Test, a cognitive shifting task (CatBat) and a picture set test. Using exploratory factor analysis, four factors were obtained: 1: Simple Alternation; 2: Mental Flexibility; 3: Perseveration; and 4: Perceptual Shift. Patients with anorexia nervosa had abnormal scores on Factors 1 and 4. Patients with bulimia nervosa showed a different pattern, with significant impairments in Factors 2 and 4. These findings suggest that differential neuropsychological disturbance in the domain of mental flexibility/rigidity may underlie the spectrum of eating disorders. (JINS, 2004, 10, 513–520.)

Several tests from the CANTAB neuropsychological test battery previously shown to be sensitive to frontal lobe dysfunction were administered to a large group of normal volunteers (N = 341) ranging in age from 21 to 79 years. The main tests included a computerized form of the Tower of London test of planning, a self-ordered spatial working memory task, and a test of attentional set formation and shifting. A computerized form of the Corsi spatial span task was also given. Age-related graded declines in performance were seen, sometimes in a discontinuous manner, especially for the attentional set shifting task (at the extradimensional shift stage). Patterns of deficits reminiscent of frontal lobe or basal ganglia damage were observed in the oldest age group (74–79). However, overall the data were only partially consistent with the hypothesis that frontal lobe functions are the most sensitive to effects of aging. Factor analyses showed that performance in the executive tests was not simply related to a measure of fluid intelligence, and their performance had a factor loading structure distinct from that for the CANTAB tests of visual memory and learning previously administered to the same sample. Finally, only limited support was found for the hypothesis that cognitive aging depends on slowed information processing. (JINS, 1998, 4, 474–490.)