The Effects of External Cue Overlap and Internal Goals on Selective Memory Retrieval as Revealed by Electroencephalographic (EEG) Neural Pattern Reinstatement.

For past experiences to guide our actions, we need to retrieve the relevant memories. Here, we used electroencephalography (EEG) to investigate how memories are selected for retrieval and to test how current goals and external retrieval cues drive selection during the retrieval cascade. We analysed data from two studies in which people studied objects in picture or auditory word formats and later recalled them using either written words (Experiment 1, n = 28) or line drawings (Experiment 2, n = 28) as retrieval cues. We used multivariate decoding to quantify the reinstatement of study phase neural patterns when people successfully identified items that had been studied in a format currently designated as targeted, compared with non-targeted items. Neural reinstatement emerged at around 500 ms post-stimulus, like the established left parietal event-related potential (ERP) signature of recollection. Reinstatement was target-selective (greater for targets than non-targets) when test cues overlapped more with targets, a pattern previously shown for the left parietal ERP. In contrast, when cues overlapped more with non-targets, neural reinstatement was reversed-greater for non-targets-unlike the left parietal ERP. We also tested for goal-directed mental reinstatement proposed to guide selection prior to retrieval cues. When words were cues, there was strong evidence of this proactive reinstatement, but it was not detected when pictures were cues. Together, the data suggest that selection can act at multiple stages of memory retrieval and depends on both external cues and goal-directed control.