Forgetting Theory 2: Trace Decay
Description AO1 points
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The theory suggests that learning causes a physical change in the
neural network of the memory system, creating a memory trace or
“engram”
Hebb (1949) looked at the brain and showed that a memory occurs
when a group of nerve cells excite (stimulate) one another
Engram = biochemical change (presumably in neural tissue) that
represents a memory
Once this memory trace has been created, it must be reinforced through
repetition to strengthen it
If the trace is not reinforced by practice it will simply weaken and
decay, causing forgetting to occur. We need to use it or lose it!
So, trace decay explains forgetting as a problem of availability – that
is, the information is lost completely from the memory system through
disuse and passage of time
Biological processes in the brain cause the trace to decay until
eventually the message it carried, is lost
Why do we forget according to the trace decay theory?
Evaluating the trace decay theory of forgetting – AO2 points
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The problem is that we do recall things we have not
thought about for a long time. For example we can ride a
bike after a long period. We have not been renewing the
physical memories in the meantime, but the memory is
still there
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Sometimes, after being presented the right cues, memories are
triggered and long-forgotten memories remembered
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Many elderly people can recall incidents from their youth in great detail.
Unless they have recalled the instance many times throughout their
lives, the trace should have decayed
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If the trace decay theory is correct, and you hadn’t
played the guitar for 20 years then not only would you
be unable to recall the chord sequence for a particular
song, but it would also take you as long to learn the
song the second time as it did the first. This simply isn’t
true.
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People under hypnosis can often recall things that they haven’t thought
about for years, so their traces may still be there
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Trace decay cannot explain why some people seem to have poor recall
of even recent events, while others have incredible memories going
back for decades. Why are there these huge individual differences?
+ Peterson & Peterson (1959)
 Had participants recall trigrams after varying intervals
 During rehearsal an Interference task was given (counting
backwards in threes) to prevent rehearsal
 They found less that 10% of information was recalled after 18
seconds
 This is evidence for trace decay in STM. Participants weren’t able
to practice/repeat the information/memory, and so the memory
traces decayed
- However, this was a laboratory experiment, so the study involved artificial
tasks and an unnatural setting, and therefore lacked ecological validity. So
the results may not be valid for the “real world”, and therefore this study
cannot support the trace decay theory of forgetting