An Essay on Cognitive Forgetting

Something a little different on the blog for you to contemplate over. I wrote this assignment essay a couple of weeks ago, and I wanted to share it, with the very minimal editing since I handed it in, as part of my Revision Pitstop section of this blog. It’s about memory and cognition – more importantly, about why we forget.


Forgetting is a cognitive term to describe when information once received and encoded via stimuli is no longer able to be retrieved. Whilst the term applies to long-term memory (which is said to have an unlimited capacity and for accessibility rather than availability to be the problem when forgetting), forgetting can occur at any stage of memory encoding and information items can be lost or altered throughout.

As cited in Rieber and Salzinger (1998), three main theories of forgetting have been proposed: interference, cue dependence and consolidation. This essay will look at the support for and arguments against interference theory and briefly contrast it with consolidation theory to see whether forgetting can be explained this way.

Said to have been first studied by psychologist John A. Bergström in 1892, ‘interference theory’ of ‘unlearning’ argues that we forget due to the interaction between new and past information in the long-term memory (LTM) system, causing a negative transfer effect of either the retrieval of past memories or in regaining new memories.

There are two types of forgetting according to interference theory: proactive and retroactive (Steinman et al, 1965). Proactive interference states that forgetting is due to prior information causing a disruption in the encoding of new information in the LTM. Retroactive interference is when new information inhibits the recall of old information, for instance, learning one’s new phone number can lead to forgetting one’s old one. Underwood (1969) described retroactive interference as being due to decreased recall in the “primary studied functions” (ie. information first encoded) due to the “learning and recall of succeeding functions” (later encoded information).

There is much support for the theory of interference. Jacoby, Debner and Hay (2001) looked at why interference might occur. Their studies into word pair association suggested that the ‘correct’ new-information response in a dual-task trial is too weak or the ‘incorrect’ past-information response is too strong, causing participants to favour the prior information. With additional simultaneous information load, people tend to forget more. Regardless of an individual’s ability to remember, doing multiple tasks always provides even a little interference when trying to remember. In this way, interference theory shows that most individuals have the same process of forgetting, and the theory’s universality makes sense from observation.

Isurin and McDonald (2001) said that the act of forgetting is stronger when new information resembles the old. They studied cross-interference in the acquisition of a new language. This suggests that when pieces of new information are encoded into our LTM they ‘block out’ or take the place of the old information automatically, therefore supporting retroactive interference theory. On the other hand, their research might support other theories of forgetting where the type of stimulus stored is more important than the interaction between information, especially since LTM has unlimited capacity. Conversely, interference theory makes assumptions that weaken it.

One such assumption (Rieber and Salzinger, 1998) is that all memory is stored in LTM intact – the failure to remember occurs in retrieval alone – whereas the information itself might be faulty or mistaken. Interference theory ignores this. Interference theory has no support from indirect memory research – most research has been looking for interference specifically, and therefore it cannot be argued that interference theory covers all aspects of the way one forgets.

It may not be possible to disprove, as well as prove, this interference theory. One can produce evidence for not being able to remember when new information is interfering with the old (ie. retroactive forgetting), but how can one prove that the opposite, that memories are not interfered, is true? For instance, Gleitman, Steinman, and Bernheim (1965) pointed out that ‘extraexperimental’ confounds could affect the results of interference theory studies, but these are difficult to experimentally prove – so it is difficult to rule out the possibility of forgetting from other theories as well as interference, even when there is no substantial research directly against interference in memory.

The memory consolidation processA different theory might better explain the process of forgetting. For instance, a further theory, consolidation theory, suggests that, rather than being a one-block process that memories are encoded and degrade, forgetting is a stage process where memories are encoded through long-term repetition. Thus, forgetting happens quicker immediately after learning. Unlike interference theory, this takes into account external factors that might affect memory – like time. Interference theory maintains that forgetting comes from the mind alone, rather than from the conditions of when information was acquired. It has also been argued (Underwood and Postman, 1973) that inference theory is too hierarchical, too focused on the single route of memory processing when explaining the encoding of new memories; consolidation theory is more flexible and suggests that some memories can exist independently of the hippocampal system in LTM, and is supported by neurobiology evidence of protein synthesis and synapsis strengthening (Gold, 2007).

Nevertheless, interference theory is also supported by studies showing that the more powerful (clearer in the mind) response to a stimulus interferes with a weaker response, regardless of which is more contextually appropriate. Anderson (2001) argued that memory selection is required during retrieval, and that forgetting is an active process. Research is still being conducted today, showing that the initial structure of the theory has been consistent over time and scientific development.

In conclusion, interference theory seems to explain reasonably well how we forget. Although the evidence for other theories, such as consolidation theory, is extensive, interference theory itself does well to acknowledge the human perspective of being constantly surrounded by new stimuli: very few people can remember the exact details of scenes in their memories because we are forever encoding new details from external stimuli. On the other hand, its narrow view of memory information being replaceable chunks fails to account for different types of memory and stimuli, and, thus, interference theory may better explain the forgetting process when used in combination with other theories of memory and forgetting.



Anderson, M.C. (2001). Active forgetting: Evidence for functional inhibition as a source of memory failure. Journal of Aggression, Maltreatment, and Trauma, 4, 185–210

Gleitman, H., Steinman, F., & Bernheim, J. W. (1965). Effect of prior interference upon retention of fixed-interval performance in rats. Journal of comparative and physiological psychology, 59(3), 461.

Gold, P.E. (2007). Protein synthesis inhibition and memory: formation vs amnesia. Neurobiology: Learning and Memory. 89(3): 201–211.

Isurin, L. (2004) Cross Linguistic Transfer in Word Order. Proceedings of the 4th International Symposium on Bilingualism. Cohen, J. (ed) & McAlister, K.T. (ed)

Jacoby, L.J., Hay, J.F & Debner, J.A. (2001). Proactive Interference, Accessibility Bias and Process Dissociations. Journal of Experimental Psychology: Learning, Memory and Cognition, Vol 27(3), 686-700

Rieber, R.W. & Salzinger, K. (1998). Psychology: Theoretical-historical perspectives (2nd ed.), 17-75. American Psychological Association, xvii.

Underwood, B.J. (1969). Attributes of memory. Psychological Review, Vol 76(6), 559-573

Underwood, B.J. & Postman, L. (1973). Critical issues in interference theory. Memory and Cognition, Vol 1, 19-40


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