Functions of external cues in prospective memory.

A simulation of an air traffic control task was the setting for an investigation of the functions of external cues in prospective memory. External cues can support the triggering of an action or memory for the content of the action. We focused on memory for the content, and manipulated the temporal characteristics of the external cue to disentangle two possible functions the cue can support: (1) an external cue visible during a retention interval could support rehearsal of the to-be-performed action; (2) an external cue visible at the end of a retention interval could support retrieval of the to-be-performed action. Two experiments were conducted that converge on the same conclusion: the primary function of an external cue is to support retrieval. Implications for the design of a computer interface to present prospective cues are discussed.