Memory inhibition

In order to remember, it is essential not only to activate the relevant information but also to inhibit irrelevant information. Imagine if, when you tried to remember where you parked your car, every place you had ever parked your car came to mind. Memory inhibition is a critical component of an effective memory system.

There are many memory phenomena that seem to involve inhibition, although there is often debate about the distinction between interference and inhibition.

Part-Set Cueing
Presenting a subset of previously learned items as retrieval "cues" often impairs recall for the remaining information (Roediger, 1973; Slamecka, 1968).

Retrieval-Induced Forgetting
Retrieving one exemplar from a set of learned items in a category can impair memory for the other exemplars (Anderson, Bjork, & Bjork, 1994). In this paradigm, participants are first asked to learn a set of category-exemplar word pairs (e.g., Fruit-Orange, Fruit-Banana, Tool-Pliers). In a retrieval practice phase, they then are cued to retrieve some of the exemplars (e.g., fill in the blank: Fruit-Or____). Finally, they are asked to retrieve all of the exemplars (e.g., fill in the blanks: Fruit-Or____, Fruit-Ba______, Tool-Pl______, etc.). In this example, retrieving "orange" would decrease the likelihood participants would retrieve "banana" but not the likelihood they would retrieve "pliers."

Think/No-Think Task and Intentional Memory Suppression
During 1990's, when the recovered memory debate was raging, cognitive psychologists were dubious about whether specific memories could be repressed. One stumbling block was that repression had not been demonstrated in a research study. While it does not address the question of whether traumatic memories can be suppressed, a study by Anderson and Green (2001) provides evidence of intentional memory suppression in a lab study. Participants were trained 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). Then, one each trial in the think/no-think phase, one of the cues from each pair (e.g., ordeal) would appear on the screen, either in red or green. Green would indicate the participant should say the other member of the pair (e.g., roach). Red would indicate they should look at the cue but NOT think about or say the associated word. 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. Importantly for the inhibition argument, this impairment even occurred when participants were given an "independent probe" test, for example, asked to fill in the blank: insect-r_____.

Aging and Impaired Inhibitory Processes
Older adults show impairments on tasks that require inhibiting irrelevant information in working memory, and these impairments may lead to problems in a variety of contexts (e.g., Zacks, Hasher, & Li, 2000).