Compatibility-sequence effects in the Simon task reflect episodic retrieval but not conflict adaptation: evidence from LRP and N2.

Behavioral and psychophysiological studies on the Simon effect have demonstrated that stimuli automatically activate spatially corresponding responses, even if their location is irrelevant to the task. Interestingly, this Simon effect is attenuated after stimulus-response incompatible trials (Gratton effect or compatibility-sequence effect), a pattern that has often been attributed to online conflict adaptation, even though an account in terms of episodic binding and retrieval is just as plausible. Here we show that the compatibility-sequence effect can be eliminated and partly reversed by rotating the boxes in which stimuli are presented in between two given trials, a manipulation that is likely to affect episodic representation but not online control. Sequential modulations of electrophysiological indicators of automatic response priming were also eliminated (N2) or even reversed in sign (LRP), suggesting that these effects are due to episodic retrieval of stimulus-response bindings but not, or to only a negligible degree, to online adaptation.