MEMORY MODELS

KINDS OF REMEMBERING
Psychologists have applied a number of techniques in their efforts to understand memory. One approach has been to subdivide the vast field of memory into areas that seem to function differently from one another. Cast your mind back to the last time you arrived home. How does that memory differ from remembering how to spell ‘table’, or that there are 11 players in a soccer team, or remembering how to ride a bicycle? Our intuition would suggest that there are different kinds of remembering. But what is the evidence? Episodic and semantic memory One distinction made by psychologists is between episodic and semantic memory (Tulving, 1983). Episodic memory (episodic memory memory for personally experienced events) can be defined as memory for the personally experienced events of your life. Such memories naturally tend to retain details of the time and situation in which they were acquired.

Semantic memory, (semantic memory abstract knowledge that is retained irrespective of the circumstances under which it was acquired (e.g. ‘the world’s largest ocean is the Pacific’)) by contrast, is knowledge that is retained irrespective of the circumstances under which it was acquired. For example, your memory of eating breakfast this morning will be an episodic one involving when, where and what you ate. On the other hand, remembering the meaning of the term ‘breakfast’ involves semantic memory. You can describe what ‘breakfast’ means but you probably have no recollection of when and how you learned the concept. Autobiographical memory – the recall of events from our earlier life – has become a particular aspect of episodic memory that has attracted considerable interest in recent years (Cohen, 1996; Conway, 1996). (autobiographical memory the recall of events from our earlier life – a type of episodic memory)

Declarative and procedural knowledge
Another sub-division of memory is between declarative and procedural knowledge (Anderson, 1976; 1995). Declarative knowledge is explicit knowledge that people are consciously aware of and can report. For example, you can probably remember eating breakfast this morning. Ryle (1949) described this type of memory as ‘Knowing That’. Procedural knowledge is a knowledge of how to do things, such as riding a bicycle or typing. Ryle referred to it as ‘Knowing How’. The skills of typing, driving and so forth may be well learned and highly developed, but it is generally not easy to describe in detail how to carry them out. So an accomplished typist might find it difficult to identify each finger movement required to type this sentence, while being quite capable of typing it quickly and correctly.

Comparison groups

Comparison groups
But it clearly is not enough to observe how often ‘gold’ appeared in the lists. Many people, when asked to think of metals, would include gold, even without having it read to them while they slept. Researchers can overcome this type of problem by examining the difference between the performance of a comparison group or condition and an experimental group or condition. So Wood et al. (1992) made two comparisons. One comparison was between groups. Some participants were awake while the words were read to them, and some were asleep. Because people were randomly assigned to the groups, comparing how often the target words appeared in each of the groups showed whether people were more influenced by presentations while they were awake or by presentations while they were asleep. People who were awake during the presentations were more than twice as likely to report the target words as people who slept. This comparison shows that learning while awake is better than learning while asleep, but it does not rule out the possibility that the sleepers’ performance was influenced by the presentations. Multiple observations were made for each participant and then compared. There were actually two different lists of words – one included ‘a metal: gold’ and the other included ‘a flower: pansy’. Each participant was read only one of the lists, but all participants were tested on both categories. This allowed the experimenters to measure how often people produced words that had been read to them compared to words that had not been read to them.

There was no real difference between individuals’ subsequent reports of key words when the words had been read to them and when the words had not been read to them. The pair of bars furthest to the left provides the same comparison for people who were awake during the word presentations. It is pretty clear that if people were awake during word presentation, then the presentations of the lists had a big effect on subsequent memory for those key words.

OVERCOMING THE PROBLEM USING MEMORY

To address this problem, memory is often studied by comparing two groups of participants or information, organized such that the ‘past event’ occurs for one group but not for the other. Because the only known difference between the groups is the presence or absence of the event, differences observed at the later time are assumed to reflect memory for that event. It is therefore essential to determine that there are no other differences between the groups. The sleep learning experiment Suppose you played tapes of information to yourself in your sleep. Would you remember the information later? (For a review of ‘sleep learning’, see Druckman & Bjork, 1994.) To answer the question, you might present some information to people while they sleep, wake them up, and then observe whether their subsequent behaviour reflects any memory for that information. Wood, Bootzin, Kihlstrom and Schacter (1992) did just this. While people slept, the researchers read out pairs of category names and member names (e.g. ‘a metal: gold ’), repeating each pair several times. After ten minutes, the sleepers were awakened and asked to list members of named categories – such as metals – as they came to mind. The assumption was that if participants had any memory for having ‘a metal: gold’ read to them while they slept, then they would be more likely to include gold in their list of metals.

OBSERVATION AND INFERENCE

OBSERVATION AND INFERENCE
Remember that memory is evident to the degree that a past event influences later behaviour. So how can we know whether the later behaviour was influenced by the past event? Try this: write down the first 15 animals that come to mind – do not read ahead – stop now and jot down a list. Next, compare your list to that on page 246. You probably had several matches. Does that mean that you correctly recalled those words? Obviously not! If you had studied the list first, could I infer that your report of an animal name was influenced by the past event? Some items you might consciously recall, some you might think of due to an unconscious influence from studying the list, and some you might think of just because they are animals – not as a result of studying the list. Would the number of matches between your list and the study list be a good measure of your memory for the list? No – the matches might occur for any of the above reasons. The demonstration with the animal list captures an important issue in memory reset arch. Memory is not observed directly – it is inferred from performance on a task. But performance on the task will be influenced by other factors as well as memory for the original event. So it is clearly important to be careful about what is observed and what is inferred in memory research.

HOW TO STUDY MEMORY

HOW TO STUDY MEMORY
Memory can be studied in many ways, in many situations. It can be manipulated and observed in the ‘real world’ (e.g. Cohen, 1996; Gruneberg, Morris & Sykes, 1988; Searleman & Herrmann, 1994; Neisser, 1982). But most research has been experimental work, comparing controlled conditions in a laboratory setting. The manipulated conditions might include any variable that is expected to influence memory, such as the familiarity of the material, the degree of similarity between study and test conditions, and the level of motivation to learn. Traditionally, researchers have studied memory for lists of words, non-words (i.e. nonsense words like ‘argnop’ or ‘DAL’), numbers or pictures, although many other sorts of materials have been used as well, including texts, stories, poems, appointments and life events. So most systematic investigations of memory have been experimental, conducted in a laboratory, and involving a set of to-be remembered words or other similar materials. This description applies well to much of Ebbinghaus’s (1885) work; he was the first psychologist to study memory systematically.

INFERRING MEMORY FROM BEHAVIOUR

INFERRING MEMORY FROM BEHAVIOUR
There are many sorts of behaviour that suggest memory for some past event. Suppose you heard a poem some time ago. Later, you might recall the words of the poem, or recognize them when you hear them again. Alternatively, the words might sound familiar without your explicitly recognizing them. Finally, you might even be influenced by the message of the poem without having any sense of familiarity, recognition or recall.

Recall
To recall information is to bring it to mind. Usually there is some cue (cue information that initiates and/or aids recall) that initiates and/or aids the recall. Examination questions, such as ‘Contrast Piaget’s developmental stages with those of Erikson’, contain content cues that direct recall to information relevant to the examiner’s aims. Questions such as ‘What did you do on Friday night?’ contain time cues. Cues such as these are very general and do not provide a great deal of information. Recall in response to these sorts of non-specific cues is generally termed free recall. (free recall recall in response to nonspecific cues) Some cues may also be more informative and direct us to more specific events or information. Short answer examination questions, such as ‘What ages are associated with Piaget’s concrete operational stage?’, target a specific response by providing more information in the cue. A question like ‘Where did you go on Friday night after you left the pub?’ differs from its counterpart above by providing more information in an effort to extract some specific material. As cues become more directive, the recall is termed cued recall. (cued recall recall in response to directive cues) Many factors influence the effectiveness of cues; one such factor is the amount of targeted information. The cue overload principle (Mueller & Watkins, 1977) (cue overload principle as more information is tied to each cue, a smaller proportion of that information will be recalled) states that as more information is tied to each cue a smaller proportion of that information will be recalled.

Recognition
Our ability to identify some past event or information when it is presented again is termed recognition. In examinations, true– false, matching and multiple-choice questions typically target the student’s ability to recognize information (e.g. ‘Traits are relatively stable personality characteristics – true or false?’). In real life, questions like ‘Did you go to see a film after you left the pub?’ suggest some event or information and ask the rememberer whether it matches the past.

Familiarity
Effects of memory can be observed without the ability to bring to mind (that is, recall or recognize) a past event or information. Feelings of familiarity are often based on memory. You have probably encountered someone who seemed familiar although you were unable to recognize them; often this familiarity is due to a past encounter with that person. One of the reasons for advertising is to make particular products more familiar to you, because people tend to prefer familiar things to more unfamiliar ones (Zajonc, 1968). Hence the old adage, ‘All publicity is good publicity.’ Unconscious influence Even in the absence of recall, recognition or feelings of familiarity, memory may still be detectable. If information has been previously encountered, subsequent encounters with the same information may be different due to that encounter, even in the absence of any overt signs of memory. Unconscious effects of memory can be problematic because they may lend credibility. When people were asked whether they believed as sertions such as ‘The largest dam in the world is in Pakistan’, they were more likely to believe these assertions if they had been encountered in a previous memory experiment, even if they could not remember these assertions in any other way (Arkes, Hackett & Boehm, 1989; Hasher, Goldstein & Toppino, 1977). Perhaps these unconscious effects of memory are the key to the effectiveness of propaganda. Priming describes the (often unconscious) (priming the effect of a previous encounter with a stimulus) effects of a past event. It can be measured by comparing behaviour following some event with behaviour that arises if that event did not occur. In the above example, belief in those assertions may be primed by having encountered them. If two groups of people are compared – some who encountered an assertion and some who did not – the difference in their belief is a measure of the priming from the earlier encounter. Here is another example of priming. Consider the word fragment ‘c _ _ p u t _ r’. A psychologist might measure how long it takes people to solve or complete the fragment to make a real English word (i.e. to say ‘computer’) and compare the time required by people who have recently encountered the word or idea with the time required by people who have not. Even when people have encountered ‘computer’ (or recently used a computer) but do not remember the experience, they can generally solve the word fragment more quickly than people without the experience. The difference in the time needed to respond is an example of priming – one type of evidence for memory (i.e. some lingering effect) of the previous experience.

MEMORY

MEMORY
Memory is far more than simply bringing to mind information encountered at some previous time. Whenever the experience of some past event influences someone at a later time, the influence of the previous experience is a reflection of memory for that past event. It is easy to see the role of memory in the case of a student who attends a lecture and later brings to mind what was taught. It may be less obvious that memory still plays a role even when the person does not ‘remember’ the lecture or the information, but merely uses information from the lecture, possibly without thinking about the lecture itself or the specific information at all.

There are even more subtle and less obvious effects of memory. If the same student later develops an interest (or a marked disinterest) in the topic of the lecture, that interest may reflect memory for the earlier lecture, even though the student might not be able to recall having ever attended a lecture on that topic. Memory plays a role to the degree that the student’s attitudes about the topic were influenced by the lecture. In the same vein, memory plays a role whether or not we intended to learn during the ‘past event’. In reality, comparatively little of our time is spent trying to ‘record’ events for later remembering; most of the time we are simply getting on with life. But past events only have to influence our thoughts, feelings or behaviour to provide evidence of our memory for them.

Just as memory is not dependent upon an intention to record events, it also plays a role regardless of our intention to recall or draw upon those past events. Many of the influences of past events are unintentional; indeed, they may even be quite counter to our intentions (e.g. Jacoby, Woloshyn & Kelley, 1989).