Methods of Studying Prospective Memory

Devising methods for studying prospective memory Opens in new window presents a challenge. However, the three methods that have been adopted include:

1. Questionnaires,
2. Naturalistic experiments and
3. Laboratory experiments.

1. Questionnaires

Questions about prospective memory have often been incorporated in a number of questionnaires, for example,

• “How often do you forget to keep appointments?” or
• “How often do you forget to take things with you when you go out?” or
• “How often do you forget to say something you intended to say?”

Problems about the validity of self-assessments of this kind have drawn interest from researchers. One difficulty is that subjects may not always be aware of failures of prospective memory.

Of course, failure to implement some plans is noticed because it brings serious consequences or earns bitter reproaches, but other failures may well pass unnoticed.

This findings suggests that self-assessment of prospective memory is likely to be inaccurate.

Several studies have reported that elderly people assess their prospective memory as better than young people assess theirs (Harris & Sunderland, 1987).

Logically, this could arise if elderly people more often fail to notice their errors, or, having noticed them at the time, they forget about them later, but Martin (1986) concluded that they were essentially accurate in their self-assessment.

She found that an elderly group rated their memory as better than a young group for keeping appointments, paying bills, and taking medicine. Objectives records of their attendance at appointments confirmed their superiority.

However, questionnaire responses do not reveal how far successful prospective remembering Opens in new window was due to the use of external reminders and how far the respondents relied on their own memory.

The apparent superiority of elderly people could also arise if their life style is more relaxed so that the demands on prospective memory are less severe for them than for the young. All these factors make questionnaire responses unlikely to be an accurate reflection of prospective memory ability.

2. Naturalistic experiments

The method that provides more objective evidence of success or failure is the naturalistic experiment.

Researchers on prospective memory set subjects a specific task, such as remembering to post a postcard or make a phone call to the experimenter at a designated time.

This method allows the experimenter to vary factors such as:

• the attention interval;
• the number and spacing of the to-be-remembered actions; and
• the incentives that are offered for successful performance.

Sometimes, prospective memory tasks are incorporated in an interview (West, 1984). In an experiment, remembering to keep the interview appointment was one test of prospective memory.

Subjects were also told at the beginning of the interview that they should remember to locate a folder and hand in to the interviewer at the end of the session.

A number of problems can arise with naturalistic experiments like these.

Although the experimenter can manipulate some of the relevant variables, there is no way of controlling other, potentially relevant, variables operating during the retention interval, such as the amount of rehearsal and the number of competing tasks.

Maylor (1990) used a telephone call task and later debriefed subjects about the strategies they had used. She classified these as conjunction cues (mentally linking making the phone call to another routine event), external cues (using notes, diaries, alarm clocks), and internal cues (relying on memory, rehearsing the task, mentally reviewing a schedule).

The older subjects did less well than the young group, but only when they were relying on internal cues. Thus, the results of the experiment were misleading unless the underlying strategies were disclosed and taken into account.

Experiments like these are examples of ones that have high ecological validity, retaining a close resemblance to the naturally occurring tasks of everyday life, but in so doing they sacrifice the element of control and are therefore difficult to interpret.

Another problem is that the number of observations (e.g., the number of telephone calls made or postcards posted) per subject is low, making the data difficult to interpret.

3. Laboratory experiments

Laboratory studies of prospective memory suffer from different problems. West (1986) designed an experiment varying the load on prospective memory. She required subjects to carry out a sequence of up to 14 actions (such as put the comb on the table, put the toothbrush in the bag) and recorded omission errors and order errors for young and older subjects.

There was a clear age deficit in ability to carry out the longer-action sequences. However, the task is a very artificial one. In everyday life people seldom need to memorize 14 unrelated actions. A number of recent studies have built prospective memory tasks into a text-processing paradigm (e.g. Evans, Wilson, & Baddeley, 1994).

For example, subjects must remember to underline certain target words in the text, to put a tick at the end of a page, to get up, and to switch off the room lights at the end of a short-term-memory task (e.g. Einstein & McDaniel, 1990).

Here, the primary task is to study a list of words for subsequent recall; the prospective task is to press a key when a target word occurs. It is arguable, however, whether such tasks are a fair test of prospective memory or whether they are tests of the allocation of attention between a primary task and a secondary task.

Even when a laboratory study of prospective memory involves a naturalistic task, the unfamiliar environment of the laboratory may affect the results. Ceci, Baker, and Bronfenbrenner (1988) studied the behavior of children who had to remember to take cakes out of the oven after 30 minutes.

The frequency and pattern of clock-checking was significantly different when the task was performed at home and when it was performed in the laboratory. At home, the children checked the clock often in the first 10 minutes but then only infrequently until the last few minutes.

Ceci et al. (1988) suggested that the children used the frequent initial checks to calibrate their subjective psychological clock with the objective external clock and then were able to rely on internal monitoring.

This interpretation was confirmed by the fact that the same calibration strategy was evident even if the clock was made to run faster or slower than normal.

In the laboratory, clock-checking was 30% more frequent and showed a different pattern, increasing in frequency across the 30-miniute period. This study is important because it demonstrates than an interesting strategy for time-based prospective remembering was only revealed in naturalistic conditions. Clearly, conclusions about prospective memory are highly sensitive to the particular methodology that is used.