Comparing Time and Event Based Prospective Memory: Effects of Delay

Prospective memory (PM) is the act of remembering to perform a future intention (Einstein & McDaniel, 2005). Time-based PM is remembering to retrieve that future intention at or after a specific time has elapsed. Event-based PM is remembering to retrieve the future intention when a specific cue or event is encountered (Sellen et al., 1997). The current project was designed to compare time- and event-based PM performance within a laboratory context. Previous research suggests that time-based tasks are more difficult to carry out because a decrease in performance (or PM cost) is often found compared with event-based tasks (e.g., Sellen et al., 1997). All participants completed a lexical decision task as the ongoing task. Participants in the event-based condition were asked to respond to a specific type of word for the PM task, and participants in the time-based task were asked to respond after a specific time has elapsed for the PM task. Delay between instruction and presentation of PM cue were manipulated in a completely between-subjects design. I hypothesized that participants would have higher PM accuracy when completing an event-based PM tasks than time-based PM tasks and a higher PM cost overall for the time-based than the event-based task. As the delay from instruction for the PM task and retrieval of the PM task increases, accuracy would decrease in both time and event-based tasks types. However, I also predicted a significant interaction between type of PM task and delay on PM accuracy and expected that delay would affect time-based task accuracy more strongly and result in a larger decrease in performance as delay increases. Overall, the current project contributes to our understanding of the differences in performance between time- and event-based PM tasks within a laboratory setting