Contextual within-trial adaption of cognitive control : evidence from the combination of conflict tasks

It is assumed that we recruit cognitive control (i.e., attentional adjustment and/or inhibition) to resolve two conflicts at a time, such as driving towards a red traffic light and taking care of a near-by ambulance car. A few studies have addressed this issue by combining a Simon task (which required responding with left or right key-press to a stimulus presented on the left or right side of the screen) with either a Stroop task (which required identifying the color of color words) or a Flanker task (which required identifying the target character among flankers). In most studies, the results revealed no interaction between the conflict tasks. However, these studies include a small stimulus set, and participants might have learned the stimulus-response mappings for each stimulus. Thus, it is possible that participants have more relied on episodic memory than on cognitive control to perform the task. In five experiments, we combined the three tasks pairwise, and we increased the stimulus set size to circumvent episodic memory contributions. The results revealed an interaction between the conflict tasks: Irrespective of task combination, the congruency effect of one task was smaller when the stimulus was incongruent for the other task. This suggests that when two conflicts are presented concurrently, the control processes induced by one conflict source can affect the control processes induced by the other conflict source