Contextual reminders facilitate prospective memory throughout target learning but increase vulnerability after reminder removal

Prospective memory often improves through repeated target encounters, but whether contextual reminders facilitate this learning or instead increase reliance on reminder contexts remains unclear. Guided by the Preparatory Attentional and Memory theory, we examined how contextual reminders influence the prospective and retrospective components of prospective memory. One hundred university students were randomly assigned to a Known, Unknown, or Control group and completed a dual-task paradigm. During Blocks 1–7, prospective memory targets were accompanied by contextual reminders in the Known and Unknown groups, but only the Known group was informed of their function. In the eighth block, every frame turned white, so the red reminder was no longer presented on prospective memory targets; the Control group underwent the same change. Behavioral measures and beta multinomial processing tree modeling assessed prospective memory performance and its components. Both reminder groups showed higher prospective memory accuracy than the Control group throughout learning, and their prospective memory responses became faster across blocks. After the reminder was removed, prospective memory accuracy declined in both reminder groups, and the Known group showed slower prospective memory and ongoing-task responses. Modeling showed that reminders enhanced the prospective component during learning, which decreased after the reminder was removed, whereas the retrospective component was selectively enhanced in the Known group. These findings suggest that contextual reminders facilitate prospective memory learning mainly through prospective processing, with explicit knowledge additionally supporting retrospective processing. However, reminder-supported benefits appear context-bound and may decline after context change.