Shrouded in Memory
Tanner Chaille: The way in which we operate is defined in large part by our memories. Memory is a core component of the human identity. In this show, we hope to explore the nuances of this fundamental aspect of our brains. These conversations aimed to illustrate the strengths, weaknesses, and mysteries surrounding remembering and forgetting. I'm Tanner Chaille. And I'm Isabel Nieves. And this is Remembering and Forgetting, a podcast by Themester. It seems like everyday brings some sort of massive scientific discovery, whether it be a new type of biofuel or the first visuals of black hole. Scientists and researchers work tirelessly to solve mysteries all around our world, but one of the least understood components of all hits very close to home. Our brains contain questions that stumped the brightest of us, even in the so-called age of information. Dr. Rich Shiffrin knows this all too well. He's been participating in and overseeing groundbreaking research on the fields of memory and cognition since the late 1960s and he's still in the lab at IU to this very day. I talked with him about his captivating career and what questions he's still trying to solve when it comes to the brain. I am sitting here in Studio 8 in, uh, Media School's Franklin Hall with Rich Shiffrin who is a director of the cognition and memory lab here at IU. Correct?
Rich Shiffrin: Correct.
Tanner Chaille: And you've done lots of research into the brain's processes of memory and attention and other aspects of cognition as well.
Rich Shiffrin: Yes.
Tanner Chaille: Um, so I just want to ask you, this is probably a really difficult question to start off with. Um, probably impossible to answer, but I want to see if you have anything for it. Is there any way you can succinctly describe how the brain develops and retain memories? It's pretty broad, so take your time if you need to.
Rich Shiffrin: Well, that's a question we'd all like to know, including all of us who do research in this field, um, how the brain does it is something that, um, uh, we really don't know yet. Um, we know memories are somehow encoded in the, uh, network of, uh, of neuronal connections and in the chemistry that governs the way the, uh, connections talk to each other. Um, but exactly how a memory, uh, is encoded and retained and retrieved neurally is something that we still don't know very well. We know a lot about the processes of memory and there's certain things about the brain and memory that we do know. I'm going back a very long time. For example, of recent memories, recent personal memories of which we call episodic or event memory, um, are uh, encoded and retained with the help of a brain structure called the hippocampus. And that's been known for a long time back in the fifties and sixties. Research by Brenda Milner was very famous for showing that if you, um, uh, temporarily disabled, for example, the hippocampus on both sides of the brain. Um, then the, uh, um, ability to store new memories of recent events stops. Um, the rest of the cortex seems to be able to operate fine so that our cognition seems to be operating normally without the hippocampus. We can carry on conversations and reason and, and discuss things and even recall, uh, previously learned memories with no trouble. But, uh, nothing that happens while the hippocampus is disabled is stored in memory. So that if you interrupt the, um, person in this state and then ask them to recall what just happened, they have no memory for it. So we've known that since the fifties and sixties, and ever since then the hippocampus has been studied extensively, um, with the idea of understanding what it is that the hippocampus does to form memories of recent events. And, um, there's a lot of talk about the fact that it, um, um, connects different, uh, aspects of the, uh, environment and, and the current context to each other. And, uh, since the recent events are defined by sort of context what's going on with the time and how we're involved with it, then as you can't connect the context to the things that are going on, then we can't form memories. The hippocampus seems to be, um, um, directly responsible for carrying out that kind of connection. So that's one thing we know and have studied over the years very extensively. If we go past that, there's a lot of mysteries remaining.
Tanner Chaille: Now, although there has been huge series of advancements, including your own on the topic of memory, a lot of questions still remain. And in fact, you also direct the memory and perception lab here at IU. Is there any work you're doing currently or overseeing currently with graduate students or the like that you find especially interesting in the field of memory?
Rich Shiffrin: Uh, very much so. Um, I'm doing projects in a variety of domains these days, some of which are in memory, some of which are in attention, some of which are in methodology and statistics, some of which are another things entirely, but there are several important projects in memory. Um, I'd say that the one currently that is - there are two currently that are going on on somewhat different subjects that are very exciting, uh, one of which is, um, a series of studies with my colleague Rob Nosofsky . Um, and some graduate students. One recently graduated, um, PHD student named Ray Sow, who's currently in Boston, um, on, um, short-term memory and how, uh, are retrieval of information from short term memory is governed by not only retrieval of recent events, but also by things we learn in long-term memory. And not only that, but we're carrying out current projects, uh, using EEG, um, uh, brain measure based on scalpal electrodes recording electrical activity from the brain, uh, which, um, allow us to get insights into, uh, how short term memory operates and what is its capacity. And then the other project is quite different. It has to do with uh, what we call the dynamics of memory. Um, the fact that um, when the stimulus is presented to interrogate memory, uh, words, say, or something else - a clue - tells us what we're supposed to retrieve. Then we start encoding that stimulus in a series of steps over time. And we extract features from the test stimulus and then we use those features as they're extracted to probe memory as we go. And this is happening over very short periods of time, perhaps milliseconds. And then, um, as we probe memory with this, uh, these features that are extracted, the number of features keeps increasing. The probe gets more and more rich until we run out of features. And when we basically are finished probing the memory at that point, it doesn't change anymore. But the dynamics of memory means that overtime as we're extracting features from the test stimulus and as we're probing memory, the um, um, information we extract from memory keeps changing in accord with the features that we have at that moment. And then we're exploring this and experiments that vary the, uh, time core set, which features actually are provided. And we can explore this, the dynamics of this process. And this is a big advance in the sense because memory modeling for, I don't know, the last, uh, 40 or 50 years has not looked at the dynamics of the memory, but has looked at it as, as a static process. As just one step and it happens. And, um, and uh, we think that it's able to explain a lot of data that was previously unexplained by taking this dynamic approach. And, uh, that's being carried out by a current student, Sam Harding. But it was also used as a basis for a publication in 2017 by a previous student, Greg Cox. Um, and that's out there already. And the work is being continued by, uh, the student Sam Harding now.
Tanner Chaille: So there's a lot of work being done to describe the more minute or, um, you know, smaller, intricate processes of memory. Um, I wanted you to, if you could perhaps, um, you've been mentioning the terms short-term memory, long-term memory, retrieval. Uh, and while all of us did learn that many years ago, at least in very, very basic layman's terms, is there any way you could, uh, describe the difference between longterm and short term memory for our audience? Just in a way that perhaps is a bit more nuanced?
Rich Shiffrin: Yeah. Um, short term memory is generally refers to personal recent experiences that we have in memory. Uh, the old example were things like remembering a telephone number we were just given and saying it to ourselves and rehearsing it in some auditory phonetic, uh, phonological form and then be able to reproduce it. And this has been studied extensively for many years. Um, but in general, short term memory refers to, uh, our, um, what we're thinking about at the moment, what it is that is in our current experience. Um, my talking to you now during this, uh, interview is my personal experience and, um, the very recent discussion we've had, like the questions you just asked and the um, um, the responses I'm making and the setting we're in form our current experience, which is what we think of as short term memory. Um, and short term memory is also where we operate the rest of memory. Where we, um, we often call it a working memory because it's, uh, where the control processes operate, where I decide what I'm going to do with memory, how I'm going to retrieve, what I'm going to retrieve and what decisions I'm going to make and so on. So these are all things that are happening in this working memory or short term memory system, which is, and it's basically, it's what it's sort of related to. It's not completely identical to our conscious experience at the moment. It's what we're sort of consciously aware of at the moment. And all of this together as what we think of as short term memory. And that's as opposed to long-term memory, which is the warehouse or the storehouse for all the memories we've learned over years. All the expertise we've developed, all the knowledge that we've accumulated, which is stored in memory. And um, that doesn't mean easy to get to it. Anybody who's had trouble remembering something, knows that it may not be easy to retrieve some of this memory. But for pretty much most of the evidence we have suggests that most of that knowledge is there. So it was relatively permanent, at least permanent if we, our brains are not subject to a serious illness, um, most of that information is present, but it's hard to extract. It's hard to get at. And then we have all these models of how we actually managed to retrieve from long-term memory. But that's the difference. Long-term memory is the permanent storehouse of all the things we, all the knowledge accumulated over the years. And short term memory is the very recent experience that we are operating with in the moment.
Tanner Chaille: And one of the things that you've mentioned through this interview is that memory of course, as with anything happening in the brain, is not an isolated experience. It's, it happens, you know, among and with different parts of the brain. Can you describe how memory is effected by other aspects of cognition, like emotions, biases, and in fact pressures from the outside world? How is memory weakened or changed by these things?
Rich Shiffrin: Well, I think that, um, the best way to answer that is to say that, uh, memories are constantly changing. Um, every time we retrieve a memory in a given context, in a given situation, we add to the memory we've retrieved with recent information that we, um, are currently operating with. So every retrieval changes memory and adds to it. And that's true whether you're talking about a recent event or we're talking about permanent knowledge that we retrieve and we are constantly adding and changing our memories all the time. And our memories that we're retrieving are not veridical. They're reconstructions based on inference and prior knowledge so that when we have some information retrieved that's from, um, you know, encoded, let's say in our neural structures somehow, and we retrieve some of that information. But we also are guessing what it is that's there because the information we retrieved is incomplete and somewhat noisy and we have to infer what might've been there. And the inference is based on our knowledge of what ought to be there. What ought to have been present. So if we're trying to retrieve something - well, there was a study that one of my students, Mark Stivers and his student carried out, um, that people who are shown a picture, let's say of a kitchen scene and are asked then questions about it recall not just what's in the scene, but what should have been in the scene. Uh, well both. They recall some of what they saw, but they also recall things that weren't present because they're in most kitchens so that they infer what should have been present and are guessing on that basis. And this is true of all of the memory retrieval. That it's an inference process that we reconstruct what probably was in our memory based on what little we can manage to achieve and what should have been present.
Tanner Chaille: And I think that's an interesting thing for people, everyday people at least, to think about because on some level, I don't think people realize that that's happening. And in fact may make very, you know, serious decisions based on memory, based on what they perceive to be true, but in fact is a product of, as you said, context of what should be there, what they would infer would be there when in fact it never really happened.
Rich Shiffrin: The best example of this then, the most serious one, uh, is based on research and findings by Elizabeth Loftus, uh, who actually visited here as a Patton Fellow a few years back. Um, and, um, she has investigated the fact that false memories can be implanted and the most serious cases were cases were well-meaning - usually well-meaning - uh, psychiatrists and, uh, others of the same sort would, um, be dealing with patients who had various problems. And that's why they're seeing the psychiatrist and the psychiatrist, uh, would think there's a good chance that the problems were caused by childhood abuse. Now it's known that there's a lot of childhood abuse going on. There's no question about that. The question, of course, is whether any particular problem was caused by childhood abuse. The psychiatrist would then engage in a long series of interviews and discussions and so on with the patients, um, asking about in one form or another about childhood abuse, gradually forming a memory that was never there. Um, so that the patient would come to believe with a very high confidence that their parents had abused them as children. Um, when there's no evidence that does actually happen there. When there had been no memory prior to the intervention by the psychiatrist that anything like this had taken place. The best evidence that we have that Elizabeth has shown was that if traumatic events had occurred, we tend to remember them. They're not repressed. We know they're there and we tend to remember them. They don't suddenly emerge as a result of psychiatric intervention. So what the psychiatrist had been doing was implanting false memories that eventually were thought of by the patient with high confidence as true. And once the patient had formed these memories, they felt real and it was almost impossible to get rid of them even when you learn that these might have been false. Some examples of this were - one was example that shows there was a, a a memory researcher who had studied, uh, the, uh, problems of false memory. He went through some kind of intervention and formed a false memory of abuse even knowing that this was likely to have happened. Once the memory was formed, he could not, uh, disbelieve the strong memory that had been formed. So this is, this can be a serious problem.
Tanner Chaille: And it goes beyond, um, the field of psychiatry. And it goes into a larger question of how is human memory affected not only by what happens inside their own brain, one's own brain, but also how it can be affected by people and outside forces. And while that is of course present in psychiatry, um, it also is present in areas like police interrogation, criminal justice. The pressures of an interrogation setting, uh, in many cases can create those kinds of false memories or falsified memories that lead to convictions on huge scales. And it's really a weakness in that system.
Rich Shiffrin: That's true. And there's been a lot of recent work on these lines trying to repair this as much as possible. It's um, very much the fact that during the long course of interrogation, something very similar to what I just mentioned happens with psychiatric intervention can take place and false memories can be implanted and become very strong. And in the final testimony, many months later after an event when they witnesses testifying, they can testify that something happened with high confidence and give the impression that some event they're testifying to is true. But in fact, that only emerged through a long series of interventions by the police. The only thing I should say about this is that when a good interrogation is carried out, immediately after a salient event and a witness reports what happened with high confidence, it actually is highly veridical. It's highly accurate. Uh, recent research, uh, by Wickstead and others have shown this. Um, so that the problem is not that we can't remember things immediately after they happen. We can do that reasonably well. The problem is that our memories are, um, uh, fallible over time and are constantly changing and can be moved in various directions through processes of interrogation and otherwise, and some of that is due to motivation. Some of that is due to desire to please the interrogator and so on. But whatever the reason is, it's the over a long period of time, the memories can, uh, uh, change and move in a direction that the interrogator can force to happen. And that's a big problem, uh, which the law enforcement, uh, around the country now is trying to take into account and repair by using new techniques that don't do this, but it's slowly coming.
Tanner Chaille: So our discussion kind of enlightened two things. One, that human memory is considered in many ways to be weak or frail or fragile or you know, subject to change. And also that through the years of research that you've been a part of and others have been a part of, there are so many questions that remain. There's so many mysteries that remain in the field of human memory. Um, you shared an analogy about a cell phone and its components through our correspondence about how we understand some parts of memory but not others. Do you mind sharing that analogy?
Rich Shiffrin: Well, there's several different things you asked there about this and I'll come back to them. But the cell phone analogy refers to the fact that um, we don't know the connection very well. Between the neural structures that make up our brain and the neural and chemical structures that make up our brain. And how 'mind' operates, how our behavior operates. What we do know. Is a lot about the anatomy of the brain. We are able to use MRI and other kinds of devices to measure brain activity in the brain. Different things are happening structurally. But the highways are the pathways that connect different neurons with each other, where they are. We know um, uh, something about which brain regions are, um, let's say, uh, primarily responsible for certain kinds of behaviors because they, uh, activate when we're carrying out those behaviors and, uh, we know something about networks. We're gradually learning about networks that, uh, operate in the brain who are carrying out various kinds of behaviors. But that doesn't tell us what the connection is between the two. What we know is anatomy. Um, so the analogy that I mentioned about a cell phone is that if one were, had no idea how a cell phone operated, um, we might examine, take it apart, examine it structurally, we might find out all its different components and where they are. We may try deleting some of the components to see what will happen in the cell phone. We might learn that if we delete one particular component that uh, let's say is involved with um, interfacing with radio signals that we lose a whole bunch of functionality. And I granted other parts of the cell phone, um, you know, seem to operate in different ways, but we would have no real idea what's going on with the cell phone.
Rich Shiffrin: We wouldn't know anything about the world wide web, we wouldn't know anything about the programming. We wouldn't know about the software that's operating in the cell phone that's doing all the wonderful things it's doing. So that's, to some extent, that's the state we're in with regard to understanding, uh, how the brain interfaces with mind. We know a lot about the structure of the brain, but we don't really know the connection between how the brain produces the processes of cognition and the mind that we are using all the time. And that that's, ongoing research, it's current research and we're hoping that, you know, we'll get more answers about how that operates as time goes on. But still a bit of a mystery.
Tanner Chaille: Yeah. Well, it's clear that you have done just loads of research on memory and you're actually on the advisory board four Themester this year. And of course the theme is remembering and forgetting. Uh, do you remember how you felt when you heard that was the theme? Did you have any specific thoughts or motivations, what you might want to do with this theme?
Rich Shiffrin: Um, I basically, I thought that I was relevant because I've done so much work on memory over the years. So when, um, this, uh, Themester came up, I thought, "gee, you know, memory is certainly a topic that everyone's interested in." Memory is everything we are, it's what makes us, our memories are what make us individuals. Everything in our, everything we are and everything we do in life is based on our memory. Otherwise we would be a lump of protoplasm. Um, um, so I thought I'd be relevant and uh, might be able to participate. Now I would say that probably as Themester has developed most of the, um, um, uh, sort of productions and so on that emerged from the semester had to do with things like, um - there were more popular culture things like films on memory, things like other kinds of things of that nature. Whereas I'm, I do basic research on the processes of memory. So perhaps, um, since I'm doing mostly basic research on how memory operates, um, I turned out to be somewhat less relevant for Themester - aside from this interview or this podcast - than let's say some of the other activities that are going on. But, um, but you know, I, I, I certainly think that memory is an appropriate topic for Themester and it's something almost everybody's interested in. And by the way, let me go back to the question you asked earlier about weakness. Because memory is both weak and strong at the same time. Whenever I am on a plane sitting next to someone and mentioned I study memory, they always ask, they always complain that they have bad memories and ask me how they can make them better. Well, what I respond is twofold. First I say, you don't have bad memories. You have bad memories for things you don't want to remember. I said, and everyone tells me of their bad memory. Then if they're a golfer, they remember every stroke they took in the last six rounds they played. Um, and where the balls landed and how they got out of the trouble and what their putt was like. You know, that's something they care about. People remember things that they care about. What they don't remember is things that they'd like to remember in principle but don't want to spend any effort encoding. So you may not remember the names of all your relatives, but you know, if you are not interested enough to try to encode them - or their may be a variety of other things that you don't remember but that you never really spend much effort in trying to encode. That's one answer. That we do have good memories for things we care about. Everyone does. The other answer is that, uh, memories work very well when we integrate them with what we already know. So memories work best and we can retrieve them best and we can store them best when we integrate any new memory we want with what we already know. Um, and the failures of memory are usually in these other domains where we are worried about the fact we can't remember things that perhaps we'd like in principle to remember, but don't really care much about.
Tanner Chaille: Well this has been a really enlightening interview. I think, um, it's important for people to understand that even though so much research exists into, as you described the basic areas of memory, there are still so many questions that remain.
Rich Shiffrin: Can I just respond to that? Did I say that I think that, um, different fields of science, um, become sort of mature and become the main area of focus of science at different points in time. Physics was early and then chemistry and then biology, you know, starting around 1950 with DNA and everything took over and so on. The next big area of development in science is going to be mind and brain and how they connect and how they operate. And I can see this going on for the next 50 or so years easily. So I think that we're just at the beginning of that in some ways. That is we're just developing the tools and techniques and measurement devices that allow us to, um, um, start down this road. So I expect that this is going to be the next part of science that is the main focus of humanity for many years to come.
Tanner Chaille: It's certainly very complex and, uh, relevant anytime in history because as you said, memory does in many ways define the people that we become, the people that we are. Um, but, uh, regardless, the research that you've done has kind of opened many of those questions up. So thank you for your work into the field of memory and thank you so much for joining us. It's been incredibly intriguing to talk with you.
Rich Shiffrin: Yeah, I thank you very much. It's been terrific and I enjoyed your questions. Thank you. It was very nice.
Tanner Chaille: Awesome. Well, thank you so much.