A NORMATIVE DEVELOPMENTAL-STUDY OF EXECUTIVE FUNCTION - A WINDOW ON PREFRONTAL FUNCTION IN CHILDREN

Normative-developmental performance on a battery of executive function tasks was investigated. Executive function was defined as goal-directed behavior, including planning, organized search, and impulse control. Measures were drawn from clinical neuropsychology (visual search, verbal fluency, motor sequencing, and Wisconsin Card Sorting Task [WCST]) and from developmental psychology (Tower of Hanoi [TOH] and Matching Familiar Figures Test [MFFT]). A discriminant task, recognition memory, was administered, and IQ scores were available on a subset of the sample. One hundred subjects ranging from 3 to 12 years old participated; an adult group was also studied. Three major results were found: (a) adult-level performance on different subsets of the executive function tasks was achieved at three different ages-6 years old, 10 years old, and adolescence; (b) the measures clustered into three different factors reflecting speeded responding, set maintenance, and planning; and (c) most of the executive function tasks were uncorrelated with IQ. The implications of these results for our understanding of the development of prefrontal lobe functions are discussed.