Ullsperger et al. (2005) investigated a phenomenon called the congruency sequence effect (CSE), which occurs when there is a decrease in the congruency effect in result from the previous trial being incongruent (i.e., iI and iC trials). To further explain, the congruency effect is the change seen in the mean reaction times [RT] when participants perform a behavioral task, such as a flanker test. Such tasks require participants to cope with distraction and employ selection for action. Increased levels of concentration result in a lagged response time for incongruent trial runs.
The authors’ specific study was motivated by prior flanker tasks and arrow experiments performed by Mayr et al. that hypothesized the CSE was the consequence of stimulus repetition priming. Such priming occurs when presented stimuli are exact repetitions or exact alternations of the one another. These repetitions and limited response options result…show more content… During sessions, subjects sat at the computer monitor and were shown four identical digits flanking a single target digit (with two identical digits on either side of the target, numbers ranging 1 through 9). The stimuli displayed consisted of congruent (flanker digits identical to target, e.g., 88888) and incongruent (flanker digits unlike target. e.g., 88688) trials and were shown in equal proportions throughout each session. Subjects then performed the 9-AFC tasks while being asked to react to the stimuli as quickly as possible with the fewest amount of errors. A 50-msec warning tone and a 1,000-msec preparatory period preceded the 100-msec long stimuli. By comparing reaction time for trial types (incompatible-incompatible [iI] and incompatible-compatible [iC]) that were taken from a set designed to eliminate feature repetitions, the authors were able to identify a CSE that they believed to be isolated from