Prospective memory

Prospective memory may be defined as remembering to remember (Winograd, 1988) or remembering to perform an intended action. One difference between prospective and retrospective memory is that instead of recalling past actions, events, or knowledge, prospective memory is self-initiated and does not operate directly on external stimuli (Einstein & McDaniel, 2000, 2005). Examples of prospective memory include remembering to take certain documents to the office, remembering to call someone at night, and remembering to take a medicine. Prospective memory consists of recalling an action or an intention triggered by either a stimulus or 'event' or a time. An example of event-based prospective memory, meeting a friend (the cue) might remind you to pass on a message (the intention). A time-based example would be remembering to watch TV at 8pm, recalling a meeting or appointment at a certain time, or to go to a store while it was open.

Event-based prospective memory can be exploited using deliberate acts that will produce a notable event at the time that the memory needs to be recalled such as setting an alarm or placing a shoe in the sink to remind you to take the trash out in the morning. Prospective memory can be enhanced by ordinary acts such as making a grocery list or a to-do list.

Attention
A current debate is the extent to which prospective memory requires attentional resources to identify a cue (reminder). That is, prior to meeting the friend to whom you need to pass on the message, are any attentional resources devoted to maintaining this intention? The preparatory and attentional and memory process (PAM) theory (Smith, 2003; Smith & Bayen, 2004) argues that some resources are always necessary.

In contrast, the multi-process model (McDaniel & Einstein, 2000) argues that a process as important as prospective memory would have a number of underlying mechanisms. According to this model, the properties of the prospective task, the nature of what you are doing at the time, and a number of other variables will influence whether cue identification is automatic or effortful.

Relatedly, it has also been argued that it may be how hard you perceive that it will be to identify the cue that mediates how much mental effort is used to monitor for it (Hicks, Marsh & Cook, 2005; Marsh, Hicks & Cook, 2005). Recent studies suggest that effortful monitoring is not always required to identify cues (Hicks, Marsh & Cook, 2005, Einstein et al., 2005). This is consistent with the intuitive experience of an intention spontaneously 'popping' to mind (Meier, Zimmermann & Perrig, 2006).