5/15/2006

The Seven Sins of Memory

Psychologist Daniel Schacter has argued that memory's trespasses can be divided into seven types: transience, absent-mindedness, blocking, misattribution, suggestibility, bias, and persistence.

In the original paper (which was hugely popular and is still highly recommended), the first sin ("transience") refers to the gradual loss of information from both short- and long-term memory. Although Schacter is unclear as to whether the primary cause of this sin is decay, interference, or "overwriting," he does argue that information can be merely lost from memory without any cause other than the passage of time.

Absent-mindedness refers to a failure of attention, either at retrieval or encoding. Neuroimaging evidence suggests that memory success is largely a function of the kinds of processing that take place during encoding, so this "sin" seems fairly well-established in the literature.

Blocking is failure to retrieve information that has been correctly encoded. One famous example of this is the "tip-of-the-tongue" phenomenon, in which people know that they know something, and may even be able to describe several features of the known item, but are unable to successfully retrieve the name of this item from memory. Typically, TOT happens with names of people and places.

Misattribution includes all failure of source memory, both when the incorrect source is identified and when it is not. The Deese-Roediger-McDermott paradigm offers a wonderful example of misattribution errors.

Suggestibility refers to the powerful influence that subtle things like question phrasing can exert on memory. Elizabeth Loftus has done a lot of work on this area of memory inaccuracy, and has found several surprising facts: people can be easily made to believe that certain things happened to them which never did (Were you ever lost in the mall as a child? Did you kick over the punch bowl at a family wedding? Loftus can make a significant portion of you believe so.)

The sixth sin is bias. One example of bias is the well-known consistency bias, in which people tend to overestimate the similarity between their current attitudes and previous attitudes.

The final sin, persistence, refers to the fact that we can't forget some of the memories we would most like to. This infamous trait of memory is at the root of problems like post-traumatic stress disorder.

In contrast to Schacter’s “seven sins of memory” (1999), I argue that all types of memory inaccuracy arise from three distinct types of memory system failure: those of maintenance, of search, and of monitoring. Failures of maintenance include problems involving prospective memory (“forgetting to remember”), rapid forgetting, and absent-mindedness. Failures of search include retrieval-induced forgetting, tip-of-the-tongue phenomena, and amnesia. Failures of monitoring include source misattribution, memory biases, and suggestibility. Finally, other memory inaccuracies may actually result from interactions among multiple sources of failure.

In this week's upcoming posts, I will review each of these categories of memory failure in turn, and describe how they can account for all types of memory inaccuracy when taken together.

PS: Here's the next in this series of posts.

Related Posts:
Redeeming Freud: Memory Suppression
How Many Human Memory Systems?
Prefrontal Cortex and Long-Term Memory

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