Memory inhibition

In psychology, memory inhibition is the ability not to remember irrelevant information. The scientific concept of memory inhibition should not be confused with everyday uses of the word "inhibition". Scientifically speaking, memory inhibition is a type of cognitive inhibition, which is the stopping or overriding of a mental process, in whole or in part, with or without intention. While some memories are retained for a lifetime, most memories are forgotten. For example, a person trying to remember where they parked their car would not want to remember every place they have ever parked. In order to remember something, therefore, it is essential not only to activate the relevant information, but also to inhibit irrelevant information. There are many memory phenomena that seem to involve inhibition, although there is often debate about the distinction between interference and inhibition.

In the early days of psychology, the concept of inhibition was prevalent and influential (e. g., Breese, 1899; Pillsbury, 1908; Wundt, 1902). These psychologists applied the concept of inhibition (and interference) to early theories of learning and forgetting. Starting in 1894, German scientists Muller and Shumann conducted empirical studies that demonstrated how learning a second list of items interfered with memory of the first list. and that to attend to one of several simultaneous stimuli, the others had to be inhibited. In the face of behaviorism during the late 1920s through the 1950s, and through the early growth of cognitive psychology in the late 1950s and early 1960s, inhibition largely disappeared as a theory.

Using inhibition to explain memory processes began with the work of Hasher and Zacks (1988), which focused on the cognitive costs associated with aging and bridging the attention memory gap.

Anderson and Spellman's model of retrieval induced forgetting suggests that when items compete during retrieval, an inhibitory process will serve to suppress those competitors. For instance, retrieval of one meaning for a word (e. g. the verb meaning of the word sock) will tend to inhibit the dominant meaning of that word (e. g. the noun meaning of sock). In 1995, Anderson and Spellman conducted a three phase study using their retrieval induced forgetting model to demonstrate unlearning as inhibition. Study phase: Participants study a list of category exemplar pairings where some exemplars are semantically similar in that they belong to another category besides the one they are explicitly paired with (e. g. Food Cracker, Food Strawberry, Red Tomato, Red Blood). Retrieval practice phase: Participants are cued to practice remembering some of the exemplars given the category cue (e. g. Red Bl ). Test phase: Given each category as a cue, the participant tries to recall the exemplar (e. g. Food C , Food S , Red T , Red Bl ). Anderson and Spellman observed that items that shared a semantic relationship with practiced information was less recallable. Using the example from above, recall of items related to practiced information, including tomato and strawberry was lower than recall for cracker, even though strawberry is part of a different pair. This finding suggests that associative competition by explicit category cue is not the only factor in retrieval difficulty. They theorized that the brain suppresses, or inhibits, non practiced attributes. They trained their participants with a list of unrelated word pairs (such as ordeal roach), so they could respond with the second member of the pair (roach) when they saw the other member (ordeal). The more frequently participants had tried to not think about a particular word, the less likely they were to retrieve it on a final memory test. This impairment even occurred when participants were given an "independent probe" test, i. e. given a similar category (insect) instead of the original cue (roach), and asked to fill in the blank on the memory test: insect r According to Anderson and Green, the fact that participants had a decreased ability to recall items they were told to forget strongly supports the existence of an inhibitory control mechanism and the idea that people have the ability to suppress unwanted memories. Though Anderson & Green's (2001) results have been replicated several times, a group of prominent psychology researchers using the same methodology as the original study were unable to replicate even the basic result (Bulevich, Roediger, Balota, & Butler, 2006). Nonetheless, a range of studies have concluded that at least 10% of physical and sexual abuse victims forget the abuse. Some studies claim that the rate of delayed recall of many forms of traumatic experiences (including natural disasters, kidnapping, torture and more) averages among studies at approximately 15%, with the highest rates resulting from child sexual abuse, military combat, and witnessing a family member murdered. A 1996 interview survey of 711 women reported that forgetting and later remembering childhood sexual abuse is not uncommon; more than a quarter of the respondents who reported abuse also reported forgetting the abuse for some period of time and then recalling it on their own. Of those who reported abuse, less than 2% reported that the recall of the abuse was assisted by a therapist or other professional. Other studies show that people who have experienced trauma usually remember it, not forget it. McNally (2001) found that women who report having either repressed or recovered memories of childhood sexual abuse have no worse memory for trauma cue words than women who have never been sexually abused. Similarly, McNally (1998) found that women who were sexually abused as children and who developed PTSD as a result of their abuse will not have any more trouble recalling trauma related words than healthy adult survivors of childhood sexual abuse or women who were never abused as children. Although the rate of recall of previously forgotten traumatic events was shown by Elliot and Briere (1996) to be unaffected by whether or not the victim had a history of being in psychotherapy, Hopper cites several studies which indicate that some abuse victims will have intervals of complete amnesia for their abuse. Peer reviewed and clinical studies have documented the existence of recovered memory; one website lists 43 legal cases where an individual whose claim to have recovered a repressed memory has been accepted by a court. Traumatic amnesia, which allegedly involves the forgetting of specific traumatic events for long periods of time, is highly controversial, as is repression, the psychodynamic explanation of traumatic amnesia. Re examine the pairs from above: Food Cracker, Food Strawberry, Red Tomato, and Red Blood. Memory inhibition theories suggest that recall of strawberry decreases when recall of tomato decreases because tomato's attributes are inhibited when red blood is learned. MacLeod argues that inhibition does not take place, but instead is the result of confusion between similar word pairs like food tomato and red strawberry that can lead to errors. This is different from tomato's attributes being inhibited. "In most cases where inhibitory mechanisms have been offered to explain cognitive performance", explains MacLeod, "non inhibitory mechanisms can accomplish the same goal" (p. 203).