Abstract

The interplay among task and subject variables in the context of children's vigilance was scrutinized in the present study to facilitate derivation of hypotheses concerning the mechanisms and processes responsible for individual differences in children's vigilance. Two distinct (AX and BX-double letter model) continuous performance tests (CPT) were administered under two levels of target density (low, high) to 352 children ranging from 6 to 15 years of age recruited from community elementary schools. A three-tier data analytic approach revealed that (a) CPT omission (OE) and commission (CE) errors represent psychometrically distinct constructs and must be examined separately; and (b) task (CPT model, target density) and subject (particularly age and IQ) variables significantly influence children's vigilance performance but show different patterns of interaction for omission and commission errors. Relationships associated with omission errors were generally more complex than those involving commission errors, nearly always involved model effects, and suggest that controlled processing characteristics associated with the BX model place greater demands on sustained attention and result in more rapid vigilance decay in children. The interaction among model, target density, and time proved contrary to expectations based on the signal probability hypothesis. Possible explanations of these findings and implications for research and clinical practice are discussed.