Daniel Schacter, a cognitive neuroscientist at Harvard University, distinguishes seven fundamental categories of memory imperfections or errors in his 2001 book The Seven Sins of Memory. SA: What are the seven sins of memory?
DS: Three of them have to do with forgetting. The first is called transience, which refers to the fact that all other things being equal, memories tend to become less accessible over time. This is the standard type of forgetting we all tend to experience. The second sin I call absent-mindedness. That results from a failure at the interface between attention and memory. Because of a lapse of attention, one may never encode the memory sufficiently. Or it hasn't faded out of memory but you become preoccupied with other things and don't retrieve the memory at the time you need to. Say on the way home you're supposed to pick up milk and eggs, and on the way you drive right past the store. Then as soon as you get home your wife reminds you and you remember it. The third kind of forgetting I call blocking. That's when a memory is available but you can't get at it, the tip-of-the-tongue phenomenon.
Then there are three that have to do with memory distortion, in which memory is present but it's wrong. The first I call misattribution. This occurs when you remember some aspect of an event but attribute it to the wrong source. In the book I tell a story about psychologist Donald Thompson, who was accused of rape by a woman who had been brutally raped. It turns out he couldn't have committed the rape because he was giving a live television interview about memory and memory distortion at the moment this woman was raped. It turned out that she was watching the show when an intruder broke into her house and raped her, and she misattributed her memory of this guy Thompson from the TV screen to the face of the rapist. That's a classic misattribution error: she remembers the face accurately but she got the source of the memory wrong. The next one I call suggestibility, which refers to the power of leading suggestions or questions to help create false memories. The next one I call bias. That refers to the fact that our current knowledge, beliefs and feelings can skew our memory for what we think happened in the past--usually to make it consistent with what we currently believe, know or feel.
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The final of the seven sins I call persistence. That involves traumatic memories, persisting intrusive memories, things you wish you could forget but you can't exclude from awareness.
SA: Are there any drugs or behavioral methods we can use to combat these sorts of errors?
DS: There's a lot of work being conducted right now to help find drugs that might combat transience and possibly the other ones as well. I think there is some hope there. Propranolol [see main bar] would be something that combats persistence. I talk a lot about [behavioral techniques] in the book. The big point I try to make is that, to know what remedy you need to take, you've first got to know which of the seven sins you're dealing with. The remedies are different for each one. For transience it tends to be more encoding techniques that help you learn new information and link it to your other knowledge much more effectively, so it stands up over time. For absent-mindedness, in contrast, it tends to be making better use of external memory aids like notebooks or electronic beepers or reminders or hints and cues that remind you to do things at a particular time. --JR Minkel