Edited by Jamie (ScienceAid Editor), Taylor (ScienceAid Editor), SmartyPants

The Ways We Forget

We've had a look at how things get into the memory, and now we shall look at how they get out, how we lose them - how we forget.


This is a theory only pertaining to short term memory. As the multi-store model says, the STM only has a capacity of 7 +/- 2 items. Therefore, when the capacity gets to its maximum, any new information will push out the old information; and so it is lost. Evidence for this can be seen in the primacy|recency effect.

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Trace Decay

This is a theory relates to both short and long term memory. In this theory, memories have a physical basis or trace, and over time this trace disintegrates. Think of how a sandcastle falls apart as the tide comes in. Below are a pair of studies into trace decay in short-term and long-term memory.

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Study Decay in Short Term Memory

Reitman (1974)

Decay in Long Term Memory

Mckenna and Glendon

Aim Investigate whether decay can cause forgetting. To investigate if memories decay over time.
Method Male students were shown a list of 5 words for 2 seconds. They then listened for a faint tone through a pair of headphones (given at 15 seconds).

Then they tried to recall the words.

215 shop and office workers volunteered to take part in a task where they learned CPR (first aid to restart the heart).

After the training, their performance was measured up to 3 years after learning.

Results Word recall fell by 24% over the 15-second interval After three months performance had fallen sharply

After three years performance was very poor.

Conclusions As the tone detection task required effort, it prevented memorizing the words but no new information was received; then the loss must have been due to decay. Skills such as resuscitation require frequent refreshing to remain good.

Hence time causes the decay of long-term memories.

Evaluation Cannot be sure that no new information was received.

Rehearsal may have taken place while waiting for the tone, despite what the researchers assumed.

Some memories are very resistive to long-term decay, i.e. there are some things that we remember well even after many many years.

This has very good ecological validity (is very life-like) because this is a real-life situation.


There are two types of interference forgetting affecting long term memory.

  1. 1
    'Proactive interference
    Where previous memories interfere with present learning. For example, if you move an item to another place, yet you keep going back to where it used to be.
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  2. 2
    Retroactive interference
    This is the opposite: present learning interferes with previous learning. For example, start using a new password, but when you have to remember the old one for another account: you can't.
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Evidence comes from paired associates tasks, where a participant has to remember pairs of words (e.g. pen - sock; paper - can) in one group, and then another group with the 'stem' word the same (e.g. pen - shoe; paper - cat). They are then asked to remember the second word when given the first. They concluded the participants became confused between the two groups of words.

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The problems with this theory are that it describes, rather than explains why we forget something; it is not hugely applicable to everyday life because we rarely associate two things with one stimulus. And finally, the effects of this forgetting disappear when given a cue.

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Retrieval Failure

Also known as cue-dependent forgetting, this is another type of forgetting relating to long-term memory. The idea behind this theory is that you remember a great deal of information in the LTM, but you just can't access it because you do not have adequate retrieval cues, but if you are given the cues, you will eventually remember. This is seen in everyday life when something is 'on the tip of your tongue', you know that you know it, but just can't remember. Once someone helps you out or gives you a hint - you can suddenly retrieve it.

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Below are two studies investigating this type of memory, the one involving divers is very easy to understand because it is so bizarre.

Study Context Dependent Memory

Godden and Baddeley (1975)

Retrieval Cues

Tulving and Osler (1968)

Aim To investigate the effects of learning environment on recall. To investigate the effect of retrieval cues on recall.
Method A group of divers was taken, half of them went underwater and half on the beach where they learned some words.

Half of those underwater went to the beach and half stayed underwater and likewise for those who learned on the beach; here they were tested on their recall of the words.

A large group of high school students were given a list of paired words to remember that were weakly related. (e.g. sky - clear).

They then were tested on these words by either free recall (coming up with whatever they could think of) or cued recall (where the first word was given).

Results Words learned under water were recalled best underwater - likewise for those learned and recalled on the beach. Cued recall was more successful than free recall.
Conclusions The environment where something was learned is very important, possibly because it provides cues that are associated with the word. Cues 'attached' to the memories facilitate memory.
Evaluation The differences between the two environments are very extreme and smaller differences (i.e. between a classroom and exam room) have less impact on recall.

With respect to the use of clues, this theory is very similar to interference, however, research by Tulving and Psotka (1971) found there was interference in paired associated (two linked words city - dirty) tasks. These effects, however, disappeared after being cued, suggesting that interference hasn't really occurred because it was merely the problem of accessing the information rather than its availability.

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Referencing this Article

If you need to reference this article in your work, you can copy-paste the following depending on your required format:

APA (American Psychological Association)
Forgetting. (2017). In ScienceAid. Retrieved Apr 2, 2023, from

MLA (Modern Language Association) "Forgetting." ScienceAid, Accessed 2 Apr 2023.

Chicago / Turabian "Forgetting." Accessed Apr 2, 2023.

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Article Info

Categories : Cognition

Recent edits by: Taylor (ScienceAid Editor), Jamie (ScienceAid Editor)

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