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Received February 22, 2002; revision received July 11, 2002; accepted October 2, 2002
A 14-min continuous performance test (CPT) requiring a high rate of responding was administered to a probability-weighted random sample of 816 9-17-year-old children drawn from a population of 17,117 children in an ongoing epidemiological and longitudinal study in Western North Carolina. Systematic main effects of improved performance with older age were found in this age range for all variables, including reaction time (RT), RT standard error, errors of omission, errors of commission, and signal detection parameters (d' and ß). Significant gender main effects included more impulsive errors, less variability, and faster RT by males, with no interactions between age and gender. There were no main effects of ethnicity or interactions of ethnicity with age and/or gender. Large main effects of interstimulus interval (ISI; 1, 2, or4-s intervals) and time block were present for most CPT performance measures. The normative data from the CPT should provide a useful framework for interpreting similar data in future studies of child and adolescent psychopathology.
KEY WORDS: ADHD; continuous performance test; normative; epidemiological.
The continuous performance test (CPT) has a long history of use for measuring processes related to vigilance, response inhibition, signal detection, and other aspects of performance (see reviews by Corkum & Siegel, 1993; Davies & Parasuraman, 1982; Losier, McGrath, & Klein, 1996). Most of the CPT studies follow the basic paradigm described by Rosvold and Mirsky (Rosvold, Mirsky, Sarason, Bronsome, & Beck, 1956) in which the subject must press a key in response to a rare target, such as the letter "X." Variations of this paradigm include an "A-X" task in which the target is an "X" preceded by an "A" (Halperin, Sharma, Greenblatt, & Schwartz, 1991) or other specific letter combinations; the CPT "Double" task in which the target is the second successive presentation of a letter (e.g., S-S; Klorman et al., 1983); and the CPT-not X in which the participant responds to all letter presentations other than the letter "X" (Conners, 1994).
All of the CPT tasks produce a standard set of performance measures. Traditional measures include the number or percentage of errors of omission and errors of commission. Errors of omission occur when the participant fails to respond to the...