Let your fingers do the walking: Finger force distinguishes competing accounts of the congruency sequence effect.

The ability to remain flexible while engaging in goal-directed behavior is a critical aspect of cognitive control. A classic example of such flexibility is the congruency sequence effect (CSE) in distractor-interference tasks. In such tasks, participants respond more slowly when a distractor cues a different response than a target (incongruent trials) than when it cues the same response (congruent trials). However, this congruency effect is smaller after incongruent trials than after congruent trials. Interestingly, recent data from the prime-probe task indicate that this CSE is largest when participants treat the distractor, or prime, as the first of two temporally separated targets. It remains unclear, however, whether the CSE in this task indexes (1) control processes that modulate response activation before the second target (i.e., probe) appears or (2) congruency switch costs that delay responses after the probe appears. To distinguish between these accounts, participants' responses were recorded with force-sensitive keys. After responding to the prime, but before the probe appeared, participants exerted greater force on (1) the key cued by the prime after congruent trials, but on (2) the opposite key after incongruent trials. These findings indicate that the ability to remain flexible while engaging in goal-directed behavior relies on control processes that modulate response activation prior to the appearance of a goal-relevant stimulus.