The Consequences Of Incongruent Trial
To equalize the number of congruent and incongruent trials, Ullsperger et al. (2005) created randomized trial sets from a pool that consisted of each possible incongruent combination once and each possible congruent trial eight times, for a total of 72 combinations for each trial type. Each trial was preceded by a 50-msec warning tone and a 1,000-msec preparatory period. The time between a participant’s response and the beginning of a new trial varied randomly from 3,500 to 5,500 msec.
In order to test their hypothesis and evaluate whether conflict adaptation was present, Ullsperger et al. (2005) analyzed whether the difference in response times in current congruent or incongruent trials (represented as C or I) was smaller when the current trial followed an incongruent trial (represented as [iI-iC]<[cI-cC], where each side of the expression represents a congruency effect).
The authors claimed that their analysis of the trials would create conditions that would eliminate the possibility of a priming confound by removing all instances of exact stimulus repetition. Therefore, finding an adaptation in the absence of repetition would indicate that response priming is not responsible for conflict adaptation, but rather would support the authors’ hypothesis that conflict adaptation is the result of attentional regulation …show more content…
This method of presentation means that for each trial there was a 50% chance that the target digit would match the flanker (as 50% of trials were congruent). For the remaining 50% of trials, each incongruent target digit would appear only 6.25% of the time. Therefore, if a participant sees that the flanker for a trial is 1, they can guess that the target digit will also be 1, as 50% of the time this will be true. This potential effect, called the contingency learning effect, is a confound as it may have affected the participants’ response times in a way that is not related to attentional control