A Vigilance Study of ADHD and Control Children: Event Rate and Extra-Task Stimulation

Abstract

An experiment was conducted to compare the performance of ADHD and non-ADHD (control) children in a vigilance task. A group of 24 Chinese children with ADHD was identified by their high scores (i.e., 2 SD above mean) on the Conners' Teacher Rating Scale (CTRS). The children were given a computerized Continuous Performance Test—Auditory (CPT-A) whereby English letters of the alphabet were presented in audio mode (through a speaker) rather than in visual mode (on a monitor screen). Performances of the ADHD children on CPT-A were compared with a group of normal peers matched on sex, nonverbal IQ, and school performances. The effects of the event rate (fast vs. slow) and extra-task stimulation (Pic vs. No-pic) displayed on a computer screen were investigated. Performance on the CPT-A was analyzed in terms of error rates (commission and omission errors) and reaction time. It was found that children with ADHD generally performed worse than normal children in that the former made more commission errors and had longer reaction times. However, ADHD children's performance tended to “normalize” when extra-task stimulation was available, especially in conditions of the slow event rate. These results are discussed in the light of optimal stimulation theory and the information processing model of cognitive functioning of hyperactivity.