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Forgetting

Forgetting. The inability to recall or recognise something that was previously learned In short-term memory Decay Displacement In long-term memory Interference Cue dependent forgetting. www.psychlotron.org.uk. Trace Decay (STM). www.psychlotron.org.uk. Trace Decay. Trace decay

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Forgetting

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  1. Forgetting • The inability to recall or recognise something that was previously learned • In short-term memory • Decay • Displacement • In long-term memory • Interference • Cue dependent forgetting www.psychlotron.org.uk

  2. Trace Decay (STM) www.psychlotron.org.uk

  3. Trace Decay • Trace decay • Based on the idea that information is physically represented as a memory trace (i.e. arrangement of neurones) • The trace is fragile and disintegrates if not constantly refreshed • After about 20s, the trace has decayed completely & recall is no longer possible www.psychlotron.org.uk

  4. Trace Decay • Peterson & Peterson (1959) • Recall of trigrams after varying intervals • Interference task to prevent rehearsal • Found less that 10% recall after 18s • Claimed evidence for decay in STM • However, interference task might have caused displacement of trigrams www.psychlotron.org.uk

  5. Trace Decay • Reitman (1974) • Attempt to avoid the confounding effects of displacement • Used a tone detection task instead of a verbal interference task • Found recall declined by 24% over 15s • Claimed evidence for decay • Seems to occur more slowly than Peterson & Peterson suggested www.psychlotron.org.uk

  6. Displacement (STM) Short Term Memory www.psychlotron.org.uk

  7. Displacement • Displacement • Based on the idea that STM has a strictly limited capacity for information • If STM is full and new information is registered, then some existing info is pushed out or overwritten www.psychlotron.org.uk

  8. Displacement • Waugh & Norman (1965) • PPs heard a list of 16 digits • They were then told one of the digits and had to repeat the one that came after it • Recall was better when the PPs were recalling from the end of the list • Consistent with earlier digits being displaced by later ones • Agrees with other findings (recency effects) www.psychlotron.org.uk

  9. Displacement • Shallice (1967) • Repeated Waugh & Norman’s study but varied the rate of presentation of the digits • Found better recall when digits were presented faster • Challenges displacement, as number of bits of info was the same • Supports decay as faster-presented digits had less time to decay www.psychlotron.org.uk

  10. Forgetting in STM Forgetting in STM is affected by: • Amount of information presented • Rate of presentation • Interval between presentation & recall • Task demands between presentation & recall • Very difficult to say whether decay or displacement is the most important process • Other factors also important e.g. acoustic similarity in the info (Baddeley, 1966) www.psychlotron.org.uk

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