Time-Related Changes in Conners' CPT-II Scores: A Replication Study

The objective of this study was to replicate an earlier study on the effect of the administration sequence on Conners' Continuous Performance Test-Second Edition (CPT-II) scores (Erdodi, Lajiness-O'Neill, & Saules, 2010). Participants were recruited at a university training clinic (13 males, 12 females; M-age = 26.7 years, SD = 13.3), and they were administered the CPT-II twice in the same day: at the beginning and at the end of the testing session. The overall trends described in the original study were observed in the present sample. However, order effects were generally less pronounced. The pre-post contrast on the Attention-Deficit Hyperactivity Disorder (ADHD) Index score was not statistically significant. The Neurological Index was more impaired at Time 2 (M = 36.3, SD = 19.7) compared with Time 1 (M = 33.3, SD = 19.9): t(17) = 1.63, p = .06, d = 0.38. Likewise, pre-post changes were detected in the number of T-scores >60 from Time 1 (M = 1.6, SD = 2.1) to Time 2 (M = 2.3, SD = 2.8): t(23) = 2.53, p < .05, d = 0.52. Time-related changes in the CPT-II scores appear to be reliable and are likely mediated by the presence of ADHD, perhaps as a precipitator of mental fatigue. Order effects have the potential to function as an emergent diagnostic marker of ADHD.