Intention deactivation: effects of prospective memory task similarity on aftereffects of completed intentions

Recent prospective memory (PM) studies indicate that intentions are not always directly deactivated after completion, but that they entail aftereffects in terms of slower ongoing-task performance and/or commission errors on repeated (no-longer relevant) PM trials. In four experiments, we investigated whether aftereffects depend on the similarity between completed and currently performed PM-tasks. Aftereffects were reduced when PM-cues differed between the two PM-tasks (symbols vs. words) compared to when PM-cues belonged to the same category (symbols vs. symbols). This could be explained by the new dissimilar PM-task shifting spatial attention away from repeated PM-cues and, thus, attenuating processing of these cues. Moreover, a switch of the PM-response (to or within the manual modality) did not result in erroneous retrieval of the no-more-relevant PM-response (i.e., commission errors) but in erroneous retrieval of the currently relevant PM-response (i.e., false alarms). In addition, aftereffects vanished in conditions, in which participants did not perform a new PM-task. This finding indicates that forming a new PM-task set might be a prerequisite for aftereffects when the ongoing task changes between the two subsequent PM-tasks. Finally, we did not find evidence that forming a new, dissimilar PM-task representation led to overwriting of the completed intention representation, and thus to a change of the content or destabilization of its activation level.