Retrieval dynamics in self-terminated memory search.

Most free-recall experiments employ a paradigm in which participants are given a preset amount of time to retrieve items from a list. While much has been learned using this paradigm, it ignores an important component of many real-world retrieval tasks: the decision to terminate memory search. The present study examines the temporal characteristics underlying memory search by comparing within subjects a standard retrieval paradigm with a finite, preset amount of time (closed interval) to a design that allows participants to terminate memory search on their own (open interval). Calling on the results of several presented simulations, we anticipated that the threshold for number of retrieval failures varied as a function of the nature of the recall paradigm, such that open intervals should result in lower thresholds than closed intervals. Moreover, this effect was expected to manifest in interretrieval times (IRTs). Although retrieval-interval type did not significantly impact the number of items recalled or error rates, IRTs were sensitive to the manipulation. Specifically, the final IRTs in the closed-interval paradigm were longer than those of the open-interval paradigm. This pattern suggests that providing participants with a preset retrieval interval not only masks an important component of the retrieval process (the memory search termination decision), but also alters temporal retrieval dynamics. Task demands may compel people to strategically control aspects of their retrieval by implementing different stopping rules.