ABSTRACT
The processing mechanisms employed in a task can sometimes be inferred by determining which sequential relationships between trials increase or decrease reaction time. In three selective attention reaction time (SART) experiments, we have examined sequential effects involving events that occurred simultaneously in both a focal channel of stimulation (to which the subject had to respond) and a distractor channel (which had to be rejected by attentional mechanisms). Our findings for 2-trial sequences demonstrated that, on the trial just after one on which the distractor and focal channels had conflicting content, subjects exhibited two levels of rejection of the distractor channel, both (a) being less affected generally by information in the distractor channel, and (b) inhibiting the response associated with the last distractor stimulus. Analysis of 3-trial sequences showed effects on reaction times due to the distractor event from the second preceding trial. This unanticipated finding indicated the existence of previously unsuspected residual (i.e., memorial) effects of unattended information. In discussing these results, we offer a taxonomy of 2-trial sequential SART effects and note gaps in the currently available data.
