How do we remember the future? A systematic review of ERP components in focal and nonfocal prospective memory tasks

Prospective memory (PM) enables individuals to remember and execute intended future actions, which is essential for everyday functioning. This systematic review synthesizes electrophysiological evidence from event-based PM tasks in healthy young adults, with particular emphasis on how cue focality shapes the temporal and spatial dynamics of neural processing. Following PRISMA guidelines, 34 EEG studies were reviewed to identify convergent event-related potential (ERP) signatures associated with preparatory attentional biasing, candidate cue detection, intention retrieval, and post-retrieval control. Across paradigms, embedding a PM task within an ongoing task (OT) modulated early neural activity, reflected in increased occipito-parietal and fronto-central activity within the first 300 ms, consistent with preparatory attentional biasing. PM cues elicited mid- and late-latency ERP modulations, posterior N300-like negativities associated with candidate cue detection, frontal orienting positivities associated with evaluative processing, late parietal prospective positivity linked to cue-intention binding and retrieval, and sustained anterior slow-wave activity associated with post-retrieval control. Nonfocal cues produced larger retrieval- and control-related activity. Early ERP effects, in contrast, appeared more strongly related to cue salience than to focality per se. Together, these findings support flexible multiprocess accounts of PM. The ERP evidence aligns with the Preparatory Attentional and Memory account's emphasis on preparatory attentional processes, supports the Two-Process distinction between attentional readiness and target checking, and is most consistent overall with dynamic frameworks proposing flexible interactions between proactive and reactive control processes.