W. Grant Willis

Executive functions in school-aged children: Potential efficacy of tasks in discriminating clinical groups.

The performance of three groups of children on a battery of executive function tasks was investigated. A double dissociation paradigm was used, including six executive function tasks (Wisconsin Card Sorting Test, Matching Familiar Figures Test, visual search, verbal fluency, Tower of Hanoi, and mazes) and two vocabulary tasks (Peabody Picture Vocabulary Test‐Revised and the Boston Naming Test). Executive function was defined as goal‐directed behavior including strategic planning, impulse control, organized search, and flexibility of thought and action. One hundred and fifteen children, aged 6.0 to 12.11 years, participated in the study (36 children with attention deficit hyperactivity disorder, 34 children with developmental language disorder, and 45 nondisabled children). Four main results were found: (a) groups differed on three of the executive function tasks, (b) groups differed on both of the nonexecutive function tasks, (c) the relationship between age and performance was linear, and (d) discriminan...

Validation of executive function tasks with young children

A multitrait‐multimethod paradigm was used to assess the stability, discriminant validity, and convergent validity of two commonly used tasks of executive functioning in a sample of 96 normal children in preschool and kindergarten. Memory served as the discriminant construct, and each construct was measured verbally and nonverbally. Results of a matrix of cross‐validated, Pearson product‐moment correlation coefficients did not fully support the construct validity of the tasks. Instead, the pattern of derived coefficients suggested that variance due to traits and to measurement methods were roughly equivalent. Research and clinical implications are delineated.

Neural Substrates of Childhood Attention-Deficit/Hyperactivity Disorder: Electroencephalographic and Magnetic Resonance Imaging Evidence

Research methods based on electroencephalogram (EEG) and anatomical and functional MRI have been used with increasing frequency in the study of childhood Attention-Deficit/Hyperactivity Disorder (ADHD). Both methods are safe and noninvasive, and their results can complement each other because of the good temporal (but relatively poorer spatial) resolution of EEG and the good spatial (but relatively poorer temporal) resolution of MRI. These methods are described, and associated recent research on childhood ADHD is summarized and critically examined. Results of this research support theories of ADHD that focus on a frontal-striatal neurological circuitry substrate, which has been implicated in neuropsychological executive functioning. A number of issues, however, such as the specificity of this finding for ADHD, remain unresolved. We conclude with an overview of advances and issues to be considered in future research on the neural substrates of childhood ADHD and advocate a developmental-contextual perspective on this disorder that acknowledges the reciprocal relations between neural structures and functions.

A guide for applying principal-components analysis and confirmatory factor analysis to quantitative electroencephalogram data

Principal-components analysis (PCA) has been used in quantitative electroencephalogram (qEEG) research to statistically reduce the dimensionality of the original qEEG measures to a smaller set of theoretically meaningful component variables. However, PCAs involving qEEG have frequently been performed with small sample sizes, producing solutions that are highly unstable. Moreover, solutions have not been independently confirmed using an independent sample and the more rigorous confirmatory factor analysis (CFA) procedure. This paper was intended to illustrate, by way of example, the process of applying PCA and CFA to qEEG data. Explicit decision rules pertaining to the application of PCA and CFA to qEEG are discussed. In the first of two experiments, PCAs were performed on qEEG measures collected from 102 healthy individuals as they performed an auditory continuous performance task. Component solutions were then validated in an independent sample of 106 healthy individuals using the CFA procedure. The results of this experiment confirmed the validity of an oblique, seven component solution. Measures of internal consistency and test-retest reliability for the seven component solution were high. These results support the use of qEEG data as a stable and valid measure of neurophysiological functioning. As measures of these neurophysiological processes are easily derived, they may prove useful in discriminating between and among clinical (neurological) and control populations. Future research directions are highlighted.

Social-Emotional Assessment Practices in School Psychology

This study examined the social-emotional assessment practices of a random sample of school psychologists in the United States. For each assessment instrument, respondents indicated frequency of use, rationale for use, information gained, importance, and scoring system used. Results indicate that projective tests remain popular, are used primarily to generate hypotheses about social-emotional functioning, are viewed as important in the assessment process, are applied for a range of purposes, and often are scored with personalized systems. Most objective tests are used to confirm hypotheses about social-emotional functioning, also are viewed as important in the assessment process, and are applied for various purposes. Surprisingly, a considerable percentage of school psychologists use personalized systems to score some objective tests. Implications of the findings are discussed.

School psychologists' diagnoses of learning disabilities: A study of illusory correlation.

Abstract We examined whether school psychologists based diagnoses of learning disabilities on irrelevant data. Nationally certified school psychologists received case study material containing both relevant and irrelevant information for diagnosing a learning disability. The psychologists indicated (a) the probability that the client was learning-disabled, (b) their confidence in the diagnosis, and (c) their decision-making strategy. They tended to base diagnostic decisions on false beliefs, which we discuss in respect to prior research on illusory correlation.

Developmental and Neuropsychological Perspectives on the Wisconsin Card Sorting Test in Children

The purpose of this study was to advance our understanding of the Wisconsin Card Sorting Test (WCST) as a measure of a set-shifting component of neuropsychological executive function among children by investigating the level of difficulty posed by the order of administering number (vs. shape and color) as a sorting criterion in the test. A total of 196 participants at three different ages groups (6, 11–12, and 18–19 yrs.) were administered the standard or a modified version of the WCST. Results revealed several age-related trends: (a) increases in the number of categories completed, (b) increases in test efficiency, and (c) differences in task difficulty as a function of the order in which the number sorting criterion was administered in the test. Implications of these findings are discussed in terms of the construct validity of the WCST for young children.

The School Psychologist's Role in the Early Childhood Special Education Program:

As part of a study to determine what role school psychologists might best fill in infant and preschool programs, a survey was conducted of school psychologists currently working with elementary- and high school-age children and of early childhood special educators employed in preschool and infant programs. The survey endeavored to ascertain how each of these groups viewed the school psychologists role, and what each group thought the school psychologist could best contribute to early childhood and infant programs. Two sets of questionnaires were analyzed representing 50 early childhood special educators and 82 school psychologists. The first examined the possible situations in which early childhood special educators might request assistance from a school psychologist. The second questionnaire asked participants to rank order their preference of consultation models. Results indicated that the two groups hold very different perceptions concerning the role of the school psychologist in early intervention programs. Implications of the survey are discussed in terms of service delivery and of school psychology training.

School Psychologists' Diagnostic Decision-Making Processes: Objective-Subjective Discrepancies.

Abstract A body of literature suggests that decision makers often lack insight into the cues or variables they use to reach conclusions. We studied this hypothesis by comparing school psychologists’ subjective versus objective cue use when analyzing three clinical cases. Working from a set of assessment data, the psychologists selected 1 of 16 categories of information at a time, based on preference. After each selection, the psychologists formulated a preliminary diagnosis, rated their confidence in that diagnosis, and rated the importance of the information in that category for the diagnosis. They continued this process until they felt they had enough information to make a final diagnosis. For all three cases, results indicated that there was little correspondence between the psychologists’ subjective impressions about the importance of information and objective measures of the impact that information had on diagnostic judgments.

A Review of the Use of Executive Function Tasks in Externalizing and Internalizing Disorders

Executive function (EF) is a complex construct that encompasses a variety of cognitive abilities that allow for impulse control, strategic planning, cognitive flexibility, and goal-directed behavior. Executive functions have been studied in nearly every major childhood disorder including externalizing and internalizing disorders. A universally accepted definition of EF does not exist, and many have criticized the broad definitions of the construct. For example, Pennington and Ozonoff (1996) noted, “in both neuropsychology and cognitive psychology, the definition of EFs is provisional and under-specified” (p. 55). Fletcher (1996) also acknowledged that EFs are difficult to define and described EFs as “factorially complex.” More recently, Jurado and Rosselli (2007) acknowledged that the fundamental question of “whether there is one single underlying ability that can explain all the components of executive functioning or whether these components constitute related but distinct processes” remains unanswered. To complicate matters, a large variety of tasks that purportedly measure executive functions have been used in the literature. What remains unclear is specifically which executive function tasks are used most often in the literature and on which executive tasks are groups most likely to differ? Hence, the purpose of this review is to conduct a systematic search of the childhood internalizing and externalizing literature to determine (a) executive function tasks that are used in the literature, (b) executive function tasks that are most commonly used, (c) executive function tasks on which clinical and control groups differ most frequently, and (d) executive function tasks on which clinical groups differ most frequently. To begin, a review will be provided regarding executive function performance of children with commonly diagnosed externalizing and internalizing disorders. Next, specific findings regarding the type, usage, and discriminant ability of executive function tasks will be presented followed by implications and suggestions for future research.