A meta-analytic study of event rate effects on Go/No-Go performance in attention-deficit/hyperactivity disorder.

BACKGROUND According to the state regulation deficit model, event rate (ER) is an important determinant of performance of children with attention-deficit/hyperactivity disorder (ADHD). Fast ER is predicted to create overactivation and produce errors of commission, whereas slow ER is thought to create underactivation marked by slow and variable reaction times (RT) and errors of omission. METHODS To test these predictions, we conducted a systematic search of the literature to identify all reports of comparisons of ADHD and control individuals' performance on Go/No-Go tasks published between 2000 and 2011. In one analysis, we included all trials with at least two event rates and calculated the difference between ER conditions. In a second analysis, we used metaregression to test for the moderating role of ER on ADHD versus control differences seen across Go/No-Go studies. RESULTS There was a significant and disproportionate slowing of reaction time in ADHD relative to controls on trials with slow event rates in both meta-analyses. For commission errors, the effect sizes were larger on trials with fast event rates. No ER effects were seen for RT variability. There were also general effects of ADHD on performance for all variables that persisted after effects of ER were taken into account. CONCLUSIONS The results provide support for the state regulation deficit model of ADHD by showing the differential effects of fast and slow ER. The lack of an effect of ER on RT variability suggests that this behavioral characteristic may not be a marker of cognitive energetic effects in ADHD.