Forgetting Explanation: Decay Theory.


Psychology (Remembering and Forgetting.) Mind Map on Forgetting Explanation: Decay Theory., created by Stephanie Price on 06/03/2013.
Stephanie Price
Mind Map by Stephanie Price, updated more than 1 year ago
Stephanie Price
Created by Stephanie Price over 10 years ago

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Forgetting Explanation: Decay Theory.
  1. Decay theory offers an explanation for forgetting in both short-term memory and long-term memory.
    1. Memories have been shown to involve structural changes in the brain and the establishing of fixed connections between neurons (Rose 1992).
      1. The decay explanation for forgetting is really a biological explanation which suggests that, unless information is rehearsed, the trace connections between neurons which make a memory permanent are not sufficiently fixed and simply fade away (Hebb 1949).
        1. This would explain forgetting in short-term memory. In long-term memory, it is proposed that memories that have been rehearsed and have become fixed as a structural change in the brain can nevertheless fade away over time if they are not used regularly.
    2. Studies by Brown (1958) and Peterson and Peterson (1958) offered support for the decay theory of forgetting from short-term memory.
      1. The experimental technique they used has become know as the Brown-Peterson task.
        1. The task involved displaying sequences of 3 consonants (3 consonant trigrams), such as 'B T F', to participants for a few seconds. Immediately after the display, participants heard a number and were then required to count backwards from this number in threes.
          1. The task of counting backwards was designed to prevent rehearsal of the trigram. It was usually found that when people were prevented from rehearsing information, it is very quickly lost from short-term memory.
            1. Performance drops by more than 50% in less than 6 seconds.
              1. The findings of studies using the Brown-Peterson technique support the view that information is lost from short-term memory through a process of decay.
                1. Other research has shown that the passage of time does not affect recall from short-term memory.
        2. Research Study: Waugh and Norman (1965).
          1. Long-term Decay.
            1. Ebbinghaus (1885) argued that even established memory traces decay over time.
              1. In other words, if memories are not used they gradually fade away as time passes. This is sometimes referred to as the Law of Disuse.
                1. Ebbinghaus investigated this himself by learning 169 different lists of 13 nonsense syllables, made up of consonant-vowel-consonant sequences (E.g. BEJ, ZUX etc), and then testing himself after different intervals of time.
                  1. He used nonsense syllables rather than real words so it would be a true test of memory, and not a test of existing memories for words he already knew and could link to other things.
                    1. He found that forgetting followed a particular pattern, known as the 'forgetting curve', with rapid forgetting at first and a gradual levelling off.
                    2. Bjork and Bjork (1992) have recently suggested a new theory of 'disuse'. They argue that memory traces compete with each other for access to a retrieval path.
                      1. Frequent retrieval of one particular memory trace strengthens its access to the retrieval route, making it easier to access in the future. At the same time, this has the effect of blocking off the retrieval route to other rival memory traces.
                        1. This theory explains why information that is not retrieved regularly becomes less easy to access, supporting the decay theory.
                2. Evaluation.
                  1. Most studies of decay involve unrealistic tasks and so have very low ecological validity.
                    1. Decay theory is difficult to investigate in a real-life way because the time between learning something and recalling it will be filled with all kinds of different events. In studies which involve a distracter task, such as Brown-Peterson, it might be the distracter task which causes forgetting, and not simply the passage of time. This would support the interference theory of forgetting rather than decay theory.
                      1. Decay theory cannot explain why people often remember clearly events that happened several years ago, even though they have not thought about them for a long time.
                        1. Solso (1995) points out that there is no evidence that neurological decay is responsible for normal forgetting, although it is obviously responsible for forgetting in conditions such as Alzheimer's disease.
                          1. Sperling's research (1960) does support the idea that information decays and is lost from sensory memory.
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