Functional Difference between Sustained and Transient Modulations of Cognitive Control in the Simon Task: Evidence from False Alarm Responses on No-Go Trials

Cognitive control in response compatibility tasks is modulated by the task context. Two types of contextual modulations have been demonstrated; sustained (block-wise) and transient (trial-by-trial). Recent research suggests that these modulations have different underlying mechanisms. This study presents new evidence supporting this claim by comparing false alarm (FA) responses on no-go trials of the Simon task between the sustained and transient contexts. In Experiment 1, the sustained context was manipulated so that a block included a larger number of incongruent trials. Results showed that participants made more FA responses by the hand opposite to the stimulus location. This suggests a generation of response bias in which the task-irrelevant location information is utilized in a reversed manner (i.e., to respond with the right hand to a stimulus presented on the left side and vice versa). Next, Experiment 2 examined the effect of the transient context and found that overall FA rate was lower when a no-go trial was preceded by an incongruent trial than by a congruent trial, whereas such response bias as that shown in Experiment 1 was not demonstrated. This suggests that the transient conflict context enhances inhibition of the task-irrelevant process but does not make the task-irrelevant information actively usable. Based on these results, we propound two types of cognitive control modulations as adaptive behaviors: response biasing based on utilization of the task-irrelevant information under the sustained conflict context and transient enhancement of inhibition of the task-irrelevant process based on the online conflict monitoring.