An experience sampling study on spontaneous future thinking and prospective memory.

Prospective memory (PM) concerns the ability to fulfil intentions in the future. Research suggested that PM is associated with spontaneous cognition. However, the role of spontaneous thoughts during intention retention remains unclear. The present study aimed to investigate prospective bias in spontaneous thoughts specifically related to pending intentions, and whether these thoughts were associated with PM performance. Healthy young adults completed the Prospective Activity Fluency Task to generate daily PM tasks, and the Prospective and Retrospective Memory Questionnaire to assess everyday PM failures. Spontaneous thoughts were collected by experience sampling, and categorized into pre-defined types, including PM-related, other future-oriented, and past-oriented thoughts. The results showed significant differences in the frequency of spontaneous thought types, with PM-related spontaneous thoughts occurring significantly more frequently than past-oriented ones. A higher proportion of PM-related spontaneous thoughts was significantly correlated with a fewer frequency of PM failures in everyday life. The current finding partially supports the hypothesis that there is a future-oriented natural reminding mechanism in the mind, constituting part of the prospective bias observed in spontaneous thoughts, which in turn is associated with better PM performance. These findings expand our understanding of the role of spontaneous cognition in PM.