Forgetful? Harvard Prof Daniel Schacter Explains Why Our Memories Are So Flawed
For this episode, we talked to Daniel Schacter, professor of psychology at Harvard and the author of The Seven Sins of Memory: How the Mind Forgets and Remembers.
Our conversation focused on the three “sins of omission” outlined in his book on memory. The big bad memory sins, in order of badness, are: absent-mindedness, transience, blocking.
Listen to the episode now for Schacter’s insights on how to remember what you have to remember and forget what you need to forget.
Benjamin Schuman-Stoler: Thanks very much for making time for the Blinkist Podcast. So I think that your book, The Seven Sins of Memory, is quite a readable book, but there’s so much in there, I thought that maybe we could focus just on the three omission sins, if that’s cool with you.
DS: That’s fine!
BS: Okay, so let’s just start there: what are the three omission sins, for the people who maybe haven’t read the book?
DS: I call them… transience, absent-mindedness, and blocking. And they’re basically three kinds of forgetting. So, as you alluded to, the book divides memory into sins of omissions, and commission. Commission involves memory distortion, when memory is present but wrong. And omission, involves different kinds of forgetting.
So transience would be forgetting that occurs with the passing of time. So, memories tend to be, or can be, transient to one degree or another.
Absent-mindedness refers to a breakdown at the interface of memory and attention. So, when we forget to do something not because it’s faded-out of memory, but either because we’re not attending to what we need to, either when we encode a memory or retrieve a memory.
And then finally, blocking occurs when memory still exists; we’re paying attention—it hasn’t faded out of our memories. We’re trying to remember, we just can’t get at information at the moment when we need it. So, it would be kind of like a tip-of-the-tongue state, if you will: the memory is there somewhere, but it’s blocked from getting out.
BS: Right. So, one question I had, for example, was: would it be a superhero trait to never have to deal with any of those sins? I mean, if you could never forget anything, would that actually be good? Because I know there’s some stuff that comes up towards the end of the book, that suggests there’s a reason why we’re prone to these sins.
DS: That’s right. There’s a reason why we have these sins. And we can easily imagine, and there are nice examples to support it, that we wouldn’t want to have every bit of information in memory available to us, or coming to mind, at every moment. Because there are a lot of things we don’t want to or don’t need to remember at a particular time. In fact, most things.
So, if we remembered everything, and we really couldn’t control the output of memory, and we had willy-nilly memories coming to mind all the time, that could be a very bad thing. And in fact, there are examples of that: there was a famous example I talked about at the end of the book, of a mnemonist by the name of Shereshevsky who could commit to memory virtually everything that he wanted to, by using various kinds of memory strategies, but he really couldn’t control his memories, and his mind was really kind of polluted with irrelevant memories that he couldn’t keep out of his mind. And that actually impaired his ability to function.
Now, it need not be the case that having a quote-unquote “good memory” or assuming a greater capacity to remember than we ordinarily do is always a bad thing. For example, there are some folks who have come to pretty widespread attention recently, since I wrote the book, who have a very high level of memory for personal experiences. So, Shereshevsky, who I just mentioned, was someone who could commit all kinds of trivial information to memory. If there were to be a memory competition, he could out-memorize anybody else. These people are not like that. They tend to just have very good memory for their personal experiences. And they’ve come to be referred to as Highly Superior Autobiographical Memory syndrome, or HSAM.
People may have seen them, there have been a couple of 60 Minute episodes that may have featured these folks. And you can ask them just about any particular episode that has occurred to them in their lives. You know, “What happened to you on December 17, 1997?” And relatively quickly, they can usually tell you at least something about what happened, which is what most of us—most of us can’t do that.
And there doesn’t seem to be a very obvious downside to the kind of memory that they have. It’s something they seem to enjoy. And something that may occur, in part, because they’re just very into their own memories and think about them a lot, and rehearse them.
BS: But are there side effects to that?
DS: Well, there’s not a crippling side effect. Most of these people are functioning in a pretty normal way. But they may be spending a lot more time thinking about their personal memories than most of us would.
BS: Right, okay. So, slight pivot here: which of the three sins of omission do you think is the most dangerous.
DS: I think, easily the most dangerous is absentmindedness: absentmindedness is the breakdown at the interface of attention and memory. And so, for example, absentminded memory errors may occur because we don’t focus on incoming information and coded in a way that we could later retrieve it. Or absentminded memory errors can occur at the time that we need to remember something but our attention is focused elsewhere and so we don’t even realize that we need to remember.
And when we’re in that state, we’re vulnerable to forgetting almost anything, including very important things. So, there’s an example in the book of a musician that was charged with the responsibility of looking after a very expensive Stradivarius violin. And he put it on top of his car and turned to talk to someone, and then just forgot that he had done that. Forgotten, presumably, if you had asked him, “Where did you put your violin?” He would say, “Oh, I just put it on the car.” He didn’t remember to remember and he went off, without this priceless Stradivarius, which turned up months or years later, was eventually recovered.
A more tragic expression of this very same kind of absent-mindedness, when you don’t realize that you need to remember, you’re not cued to remember at the moment you need it, has to do with the very sad phenomenon of parents—well-intentioned parents—forgetting that they have an infant in the car, and leaving that infant in their car. And in some cases in very hot conditions that result in the death of the infant.
BS: I just had my first kid in December. And in the weeks leading up to the birth, I was having nightmares about this actually, but I can thankfully report that I have not yet forgotten my kid at all. So that’s good. Those are terrifying—much more terrifying than the old, I-forgot-my-glasses-on-top-of-my-forehead stories.
DS: Exactly. But it stems from more or less the same basic processes, just operating where the stakes are much higher. And the good thing about it, is simply being aware of the possibility that something like this can occur is possibly the best preventative medicine.
And in fact, some people who have high-level or high-functioning professional parents, who have had to experience this, I think have gotten behind the idea of putting a reminder, putting something related to the child, hanging off your front mirror, to remind you that the child is there. Because, again, it almost seems absurd to think that you could forget the child was there, but it happens. You know, on an infrequent but regular basis every year, so awareness that it can happen and taking preemptive steps is an effective solutions.
BS: You also have a few other solutions—or, ways to fight absent-mindedness, as if it’s like a bad guy. One thing that stuck with me, is this idea, the way it relates to cognitive resources. I mean, cognitive resources is something I’ve heard other authors talk about on this podcast. When it comes to focus, for example. And eliminating distraction and operating at a high level, whether in athletics or in work or in solving mathematical problems. Or what have you. And I didn’t know that, actually, that availability of cognitive resources can also lead to absent-mindedness.
You discuss “operating on automatic.” And I’d love to hear, I mean, can you give some more examples of operating on automatic, that we should all look out for, and how we fight that off?
DS: Well, it’s a tricky thing, operating on automatic, with respect to the thing you forget. For example, the trivial examples which we all know, and which you alluded to already, would be, you know, I put my glasses down, I’m not paying attention to that. Or I put my keys down and suddenly—where are my glasses, where are my keys? I was operating on automatic when I carried out the action of putting them down, for example, in some unusual place. But the reason I may have been operating on automatic with respect to that particular action is that maybe I was absorbed in thinking about the idea for a new experiment. I’m thinking about that and I’m not thinking about the other thing.
So, it’s not as if these absent-minded errors result because we’re operating like a zombie, it’s that—the critical notion is what you alluded to before—it’s that there are limitations on cognitive resources and if we’ve got all our cognitive resources focused on something that might be very important, then something that at the moment would seem less important, like automatically putting my glasses down, or keys down, can then end up being very irritating.
So one way to try getting around that is to, for example, for keys or glasses in your home or your office, to have a very regular spot, where that’s the only place where you put those things. And again, that’s not going to be 100% foolproof in preventing you from—if you’re very absorbed in something else—from doing it without awareness. But if you get into the habit of that, I’ve tried that, and it’s worked for me over the years, because I’m naturally somewhat prone to absent-mindedness, to try to have a particular spot for things like keys and glasses that I’m prone to just putting down without thinking about it.
BS: And another part of this is encoding, right? Making sure that something is encoded properly. So how do we do that?
DS: Encoding is a very fundamental aspect of memory. It really has an impact, in one way or another, on all these seven sins that I talk about. The fundamental idea behind encoding is that memory is not something that—memory is something that very much depends on how we think about our current situation. And the extent to which we activate things that are already in memory: bring knowledge to bear on thinking about a new situation.
So we know, for example, from years and years of laboratory experiments, that if I do a really simple experiment and show you a bunch of words to remember, then the likelihood that you’ll later remember these words on a test can vary from near 100% to close to zero, depending on how you encode those items in the couple of seconds that it takes to think about them or encode them.
For example, if I say, “Okay, I want you to remember this word,” and the word is ‘democracy,’ and I say, “Now think about, does democracy refer to an abstract or concrete concept?” That gets you thinking about the meaning of the word, linking it up to other things you know, and, with that kind of encoding task, there’s a very good chance that later on you’ll remember that I asked you to remember the word ‘democracy.’ If, on the other hand, I say, “Well, are there more vowels than consonants, in the word ‘democracy?'” That results in a very low-level, or superficial kind of encoding of the information. And there’s a very good chance you won’t remember it at all later on.
So, the take-home message for everyday life is that, when you know there’s something you want to remember—it might be something that somebody tells you, a new fact you find interesting, or an appointment you want to keep—what you want to try to do is try to is elaborate on that information. Try to relate it to other things you know. Try to ask yourself questions about the information: How much do I like this? How does this relate to other things? The very act of elaborating on the information, linking it up with other things in memory, is one of the most powerful tools we have to encode information at a deep level and boost the probability of remembering it later on.
BS: That’s great. So, you mention that memory has a lot to do with how we think about our current situation. But you told me before we started this interview, that you’re working on how memory affects the future.
DS: Yeah, we tend to think of memory as being all about the past. Remembering the past. But one of the things we’ve learned, from research in my lab and others over the past decade or so, is that remembering the past has a lot in common with imagining the future.
When we imagine a future experience, it turns out that we activate many of the exact same brain regions that come online when we remember a past experience. And we think that’s because we’re using memory. We’re taking bits and pieces of memory to project into the future. And when we think about the future, we’re very much relying on memory–because a useful memory system is one that allows us to take our past experiences, recombine them, and simulate upcoming situations that might occur to us.
That’s a very valuable thing to be able to do. To use our past experience to imagine how new situations, or similar situations, might play out.
So, even though we tend to think of memory as something that allows us to go backwards in time, we’ve become very interested in how it allows us to use the past to project forwards in time into the future and engage in important cognitive functions like planning, for example.
We’ve just become a lot more interested in how memory shapes future thinking.
BS: Do you have enough time to tell me about one experiment you guys have done on this?
DS: Yeah, so, for example, one of the earliest experiments we did on this was using functional brain imaging, functional MRI, functional magnetic resonance imaging, where we can put people in the scanner. This is a very simple experiment. We give them a cue word—could be just about anything, for example, the word “table”—and in one condition, we ask them to remember a past experience related to a table, and in another condition we ask them to project into the future and imagine an experience related to a table. And then in a third condition, a control condition, we would ask them to make a judgement about what a table is.
And a striking finding was that there are certain parts of the brain that we know are involved in memory—the Hippocampus is one of them, parts of the frontal lobe are others, there’s a whole network of regions that come online when we remember past experiences. What we saw, very strikingly, is that it’s pretty much the same regions that came online when we asked people to imagine a future experience and remember a past experience, compared to the control test.
We’ve done other experiments where we’ve seen that older adults—let’s say people in their 70s and 80s—tend to have problems remembering details of specific past experiences, that’s a very well-established finding. And as we get older, we remember the gist of what happened, but we tend to lose out on some of the specific details. We also did experiments showing that, with older adults, when you ask them to imagine the future, they also imagine the future with less detail than do younger adults, in a way that parallels how they remember the past with less detail.
This can have an impact on things like planning and problem-solving, this reduced ability to imagine details of future experiences. So we’ve come out in a few different ways, through brain imaging studies, studies of aging, and studies of healthy young adults as well.
BS: It sounds like it’s going to have some really interesting implications, though, just in terms of how we all think of memory. Are you writing another book or planning to collect all of that info somewhere?
DS: I’m hoping to put together a book eventually on this topic, because we’ve been writing a lot of articles about it. Nothing immediately planned. Most of my current book-writing is tied up with an introductory psychology text which I’ve co-authored for the past few years. So, the time I’ve had for book-writing is going into that but eventually I do hope to pull all this work together on memory and the future and put into a book form.
BS: Cool. Well, we’ll keep an eye out for it and hopefully we can do this, when that new book comes out also.
DS: Okay, I’ll look forward to that.