The Wisconsin Card Sorting Test and the cognitive assessment of prefrontal executive functions: A critical update

For over four decades the Wisconsin Card Sorting Test (WCST) has been one of the most distinctive tests of prefrontal function. Clinical research and recent brain imaging have brought into question the validity and specificity of this test as a marker of frontal dysfunction. Clinical studies with neurological patients have confirmed that, in its traditional form, the WCST fails to discriminate between frontal and non-frontal lesions. In addition, functional brain imaging studies show rapid and widespread activation across frontal and non-frontal brain regions during WCST performance. These studies suggest that the concept of an anatomically pure test of prefrontal function is not only empirically unattainable, but also theoretically inaccurate. The aim of the present review is to examine the causes of these criticisms and to resolve them by incorporating new methodological and conceptual advances in order to improve the construct validity of WCST scores and their relationship to prefrontal executive functions. We conclude that these objectives can be achieved by drawing on theory-guided experimental design, and on precise spatial and temporal sampling of brain activity, and then exemplify this using an integrative model of prefrontal function [i.e., Miller, E. K. (2000). The prefrontal cortex and cognitive control. Nature Reviews Neuroscience, 1, 59–65.] combined with the formal information theoretical approach to cognitive control [Koechlin, E., & Summerfield, C. (2007). An information theoretical approach to prefrontal executive function. Trends in Cognitive Sciences, 11, 229–235.].     

Neurocognitive Functioning in AD/HD,Predominantly Inattentive and Combined Subtypes

The Predominantly Inattentive (PI) and Combined (CB) subtypes of AD/HD differ in cognitive tempo, age of onset, gender ratio, and comorbidity, yet a differentiating endophenotype has not been identified. The aim of this study was to test rigorously diagnosed PI, CB, and typical children on measures selected for their potential to reveal hypothesized differences between the subtypes in specific neurocognitive systems (anterior vs. posterior attentional systems) and processes (arousal vs. activation). Thirty-four CB and 26 PI children meeting full DSM-IV criteria for subtype both in school and at home, without confounding reading disability or emotional disorder, were enrolled along with 20 typically developing children. Neurocognitive functions measured included attention, inhibitory control, working memory, learning, and executive functions. Tasks included the Stroop, Wisconsin Card Sorting Test, Continuous Performance Test (CPT). Buschke Selective Reminding Test, ad the Tower of London (TOL), as well as instruments developed by Posner and Sternberg, and tasks assessing the impact on reaction time of [corrected] varying preparatory intervals and stimulus/response complexity. After co-varying for IQ, subtypes differed primarily on measures of impulsivity during tests of vigilance (CPT) and executive function (TOL), with the CB group showing greater impulsivity than both other groups. In addition, the PI group showed worse performance than CB and control groups on the WISC-III Processing Speed Index. Whether analyzed with or without an IQ co-variate, there was no support in the data for hypothesized differences between subtypes in functioning of the anterior vs. posterior attentional systems, nor in involvement of arousal vs. activation processes. The results indicate that the PI and CB subtypes are best differentiated by ratings, observations and tests of cognitive tempo and behavioral impulsivity. Neuropsychological methods have yet to identify critical neuropsychological [corrected] substrates of these differences.     

Is problem solving dependent on language?

There has been a long-standing debate in the fields of philosophy and cognitive science surrounding the relationship of language to cognition, but the exact nature of this relationship is still unclear (Sokolov, 1968/1972). In the current study, we explored the role of language in one aspect of cognition, namely problem solving, by administering the Wisconsin Card Sorting Test (WCST) to stroke patients with varying degrees of language impairment (Experiment 1) and to normal participants under conditions of articulatory suppression (Experiment 2). In Experiment 1, there was a significant correlation between performance on the WCST and language measures such as comprehension and naming. Demonstrating the specificity of this result, we also found a significant relationship between language performance and another test of problem solving, the Raven's Colored Progressive Matrices, but no relationship between language and a test of visuospatial functioning. In Experiment 2, normal participants were significantly impaired on the WCST under conditions of articulatory suppression, relative to a baseline condition. Together, these findings suggest that language plays a role in complex problem solving, possibly through covert language processes.     

The effects of task and practice on search for invisibly displaced objects

The ability to successfully search for an invisibly displaced object is frequently assumed to relate to the emergence of mental representation at around 2 years of age. However, little is known about what is actually being measured in the typical “stage 6” object permanence search task. Two studies examined the effects of task factors and practice on invisible displacements and systematic search tasks to show that simple variations in ways of hiding an object change the child's ability to find it. Experiment 1 compared two common methods of presenting invisible displacements items to 36 children, approximately 2 years of age. One task was significantly easier than the other, despite the fact that they contained identical items that varied only in their order of presentation. Experiment 2 tested the effects of short-term practice on 18- and 24-month-olds' success on invisible displacements trials and on two systematic search tasks. Results indicate that too little practice inhibited performance in 18-month-olds, but that practice beyond an optimum level did not further affect their scores. In contrast, 24-month-olds continued to benefit from increased practice until they reached the maximum possible score. The findings are interpreted to mean that invisible displacements tasks may require only sensorimotor search strategies rather than representation. The findings also have implications for (a) research that attempts to relate object permanence to other variables and (b) programs that use object permanence as an assessment or screening measure.     

Acquiring new word meaning: What does it tell us about development

R. J. Sternberg (1984, Developmental Review, 4, 113–138) offers a thoughtful and provocative essay on how individuals acquire meanings for novel or unfamiliar nouns. The Sternberg essay, however, is incomplete on a number of grounds. By stressing general processes and specific knowledge as critical components in the acquisition of verbal concepts, for example, it overlooks two logically complementary categories—specific processes and general knowledge—and the role these play in the acquisitions in question. A second concern is that the paper blurs distinctions among development, short-term learning, and the origin/acquisition of individual differences. Finally, Sternberg is encouraged to frame the specific phenomenon described here within the context of a larger theory of intellectual development and to indicate what else this specific model can be used to explain.     

Theoretical and methodological analysis of partial knowledge

A theory of partial knowledge is proposed as an explanation of cognitive development, and methods are described for testing the theory. The theory consists of three structure-process pairs, each of which postulates a type of cognitive structure and a developmental process specific to that type. In restricted knowledge, a unitary algorithm is the cognitive structure, and amendment is the developmental process. In variable sampling, a structure of unitary substitutes is paired with a process of selection. In variable integration, modular components are paired with self-monitoring. Methods for testing the theory form a sequence of mathematical models. The first model in the sequence, called a model of double assessment, is described both verbally and mathematically. Other models in the sequence are described verbally with reference to other articles for the formal mathematics. Also described are some nonmathematical methods to be used as sequels to the double assessment model.     

Methodological issues in language acquisition research with very young children

It is suggested that the dominance of observational methods in child language research with very young children has limited progress in understanding the language acquisition process. Evidence is presented that, contrary to popular belief, naturalistic methods do not guarantee ecological validity, nor are they free of task biases. Furthermore, observational studies do not necessarily provide better measures of linguistic competence than do more structured methods. Instead, it is argued that new insights from cognitive developmental research are applicable in studying language production in children younger than 3 years. A number of structured techniques are reviewed that have been used or could be used to study language production. It is concluded that a combination of methods is necessary in order to disentangle and control the many variables that enter into the language acquisition process.