Evidence for a reactionary account of retrieval state initiation.

Engagement of the retrieval state (or mode) is theorized to be a precursor to successful retrieval, but precisely when the retrieval state is engaged is unclear. Our aim in the present study is to determine the time course of retrieval state initiation. Based on growing evidence that the retrieval state reflects internal attention, we hypothesize that the retrieval state is reactionary rather than preparatory, whereby the retrieval state is engaged following - rather than preceding - a stimulus. We collected scalp electroencephalography data during a mnemonic state task in which we explicitly biased participants to engage in either retrieval or encoding states, and in which we manipulated the stimulus onset asynchrony (SOA) between the instruction and stimulus onsets. Our general expectation is that selective engagement of the retrieval state will only occur after stimulus presentation and thus be unaffected by the SOA. Our behavioral results show that regardless of the SOA, a bias to retrieval compared to encoding leads to worse memory for object stimuli. Using cross-study multivariate pattern analyses, we find robust engagement of the retrieval state approximately 500 ms following stimulus onset and no evidence for selective retrieval state engagement during the instruction interval. Together, these findings suggest that retrieval state engagement is reactionary and is consistent with the retrieval state reflecting internal attention engaged in the attempt to access stored information.