Forgetting in Short-Term Memory

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Forgetting in Short-Term Memory

Trace decay theory in STM relates to theories of Duration in STM.

The theory suggests STM can only hold information for between 15 and 30 seconds unless it is rehearsed Brown & Peterson (1959). After this time the information Decays (fades away). Waugh & Norman (1965) used the Serial Probe Technique to test the theory.

Participants were given a series of numbers to learn. They were then given one of the numbers and asked which number followed it. For example; participants were given the Probe word 7 and asked what followed it, the answer is 3.

The numbers were presented at different speeds therefore the faster the numbers presented the better the recall if Trace Decay theory is correct as the more likely the information is to remain in the STM.

The results did not support the theory. This research employed the laboratory experiment and its validity can therefore be questioned.

The idea of displacement in STM causing forgetting relates to the Capacity of STM as proposed by Miller (1956). It simply suggests that if the capacity of STM is limited to 7 plus or minus 2 items or chunks of information then STM is full then some of that information must be kicked out or displaced in order for new information to enter.

This theory suggests that all information received is stored in LTM but that some information is difficult or impossible to access.

This idea is characterised by the Tip-of-the-Tongue Effect (TOT) where we know something but just cannot recall it. Retrieval of such information is thought to be dependent on three factors:

  1. Firstly Context-Dependent Retrieval which suggests that recall of information depends on replicating the situation or context in which that information was originally encoded.

    Godden & Baddeley (1975) provided evidence for this by asking participants to learn a list of words either on land or 15 ft underwater. They were better able to recall words if asked to do so in the setting in which they originally learnt them.

  2. Secondly, State-Dependent Retrieval suggests that recall is improved if the individual is in the same physical and/or psychological state as when they first learnt the information.

    Godwin (1969) investigated the effect of alcohol on recall and found individuals were better able to recall information learnt when drunk if they were drunk. Other drugs seem to affect memory similarly. Bower (1981) however found that the same principle applied to mood did not have such a convincing effect but only a tendency to produce State-Dependent Retrieval.

  3. Thirdly, recall may be by the presence of cues or probes, clues or associations. This is referred to as Cue-Dependent Retrieval, Tulving & Pearlstone (1966).

This idea suggests that information in LTM may become confused or combined with other information during encoding thus distorting or disrupting memories.

Interference in LTM is thought to be either proactive where old memories disrupt new memories or retroactive where new memories disrupt old memories. Both Proactive and Retroactive Interference is thought to be more likely to occur where the memories are similar, for example: confusing old and new telephone numbers.

McGeoch (1932) tested these ideas using laboratory experiments involving lists of single words or binary associations. The findings therefore can be criticised for their ecological validity including demand characteristics and representativeness thus making generalisations impossible.

Forgetting in Short-Term Memory

Flashbulb memories involve the vivid recall of what individuals were doing when a major event occurred. This event may be a public or a private occurrence.

Describe what you were doing when you heard that Princess Diana had died.

Is the memory vivid and distinct in time?

Brown & Kulik (1977) asked people a series of questions about 10 major events. Participants remembered where they were, what they were doing and the emotional impact it had. These memories may be seen as 'special' and are thought to involve special brain mechanisms.

Rubin & Kozin (1984) showed that flashbulb memories are particularly powerful for personal events, such as love at first sight.

Ask your mother/father about your birth or onset of labour?

McCloskey (1988) suggested that flashbulb memories are as prone to forgetting as ordinary memories.

Bohannon (1988) suggested that flashbulb memories are not prone to forgetting when the event produced strong emotional reactions.

Repression, according to Freud (1800s) is the unconscious forgetting of traumatic events, feelings, thoughts because they are too painful to remember.

These memories are said to be repressed or 'pushed out' of consciousness into the unconscious and are very difficult to recall. These repressed memories may be the cause of mental abnormality as they express themselves in some other way.

There is increasing evidence of repressed memory in cases of childhood sexual abuse. Williams (1994) examined records of young women who had been treated for sexual abuse as children and seventeen years later 38% of them had no conscious recall of the abuse.

Zimbardo (1995) reported the case of Eileen. In 1989 Eileen suddenly remembered the reason for her childhood friend, Susan's, disappearance twenty years earlier. Eileen's father had raped and murdered her. Eileen had repressed this memory due to threats from her father and the understandable trauma it caused. Her father was sentenced to life imprisonment.

Often however repressed memories are difficult to substantiate which has led to the notion of False Memory Syndrome (Pynoos & Nader 1989) where recall of so-called repressed memories may be false although real to the person remembering them.

Repression as a theory of forgetting is based on Case Study evidence and therefore is impossible to generalise from or replicate. Case studies are highly subjectiveand tend to personal and subjective interpretations.