Explanations of Forgetting in Short Term Memory

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Explanations of Forgetting in STM

The Decay Theory of Forgetting
The decay theory of forgetting in STM states that forgetting is due to disruption of the active trace. The active trace is the engram that is formed when learning, which is very delicate. With learning the engram grows stronger until a permanent engram is formed, which is called a structural trace. One limitation to the theory is that it attempts to explain why forgetting increases with time. But this has been shown may not be true. By a study of Jenkins and Dallenbach, 1924, forgetting was increased when participants were awake, more than for the participants who went to sleep right afterwards. Another limitation that was proposed by Solso 1995, is that there is no evidence that the major cause of forgetting from LTM is neurological decay. The Peterson and Peterson (1959) experiment has provided evidence of the role of decay in STM forgetting. If decay occurred, recall of information would be poorer by time. They showed rapid forgetting of trigrams and it was concluded that the forgetting was caused by decay. The results of the experiments show good evidence for the theory. Hebb (1949) argued that when learning, an engram will be formed, which is very delicate and vulnerable to disruption. But with learning, the engram grows stronger until a permanent engram is formed, which is called the structural trace) through changes in neurons. The part where the engram is vulnerable to disruption during the active trace stage, could account for the decay theory. One limitation to this theory is that there is no direct connection between the active trace and decay. It is not explained very well in the description.

The Displacement Theory in Forgetting
The displacement theory in forgetting states that when a system is ‘full’, in STM where there is limited capacity, old information may be displaced by new incoming information that pushes out the old information. Two limitations to...
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