Levels of selective attention revealed through analyses of response time distributions

The present research examines the nature of the interference effects in a number of selective attention tasks. All of these tasks result in interference in performance by presenting information that is irrelevant to task performance but competes for selection. The interference from this competing information slows the response time (RT) of participants relative to a condition where the competition is minimized. The authors use a convolution of an exponential and a Gaussian (ex-Gaussian) distribution to examine the influence of interference on the characteristics of RT distributions. Consistent with previous research, the authors show that interference in the Stroop task is reflected by both the Gaussian and exponential portions of the ex-Gaussian. In contrast, in 4 experiments they show that several other interference tasks evidence interference that is reflected only in the Gaussian portion of the ex-Gaussian distribution. The authors suggest that these differences reflect the operation of different selection mechanisms, and they examine how sequential sampling models accommodate these effects.