Too Many Connections? How Aging Impacts Memory and Recall

How does the brain’s memory function change as we grow older? What recent discoveries are helping us understand these changes better? 

In this episode of Under the Cortex, Özge Gürcanlı Fischer Baum welcomes Karen Campbell of Brock University to discuss how aging impacts memory. Campbell shares insights from her recent study in APS’s journal Current Directions in Psychological Science, exploring the hyber-binding hypothesis. The conversation delves into how the abundance of connections in older adults’ mental representations may contribute to memory challenges later in life. 

Send us your thoughts and questions at  [email protected].

Unedited Transcript

[00:00:00.270] – APS’s Özge Gürcanlı Fischer Baum

Have you ever wondered why it seems harder to remember things as we get older? Does our memory decline with age? Is there more to the story? I’m Özge Gürcanlı Fischer Baum with the Association for Psychological Science. In this episode of Under the Cortex, I’m joined by Karen Campbell from Brock University, who recently published an article on this topic in our journal, Current Directions in Psychological Science. Together, we will discuss how our memory performance changes over time and what that means for our ability to recall information. Karen, welcome to Under the Cortex.

[00:00:46.980] – Karen Campbell

Hi, thank you for having me.

[00:00:49.360] – APS’s Özge Gürcanlı Fischer Baum

I would like to start with our first question. What type of psychologist are you?

[00:00:54.930] – Karen Campbell

I’m a cognitive neuroscientist with a specialization in aging and memory.

[00:00:59.660] – APS’s Özge Gürcanlı Fischer Baum

Today, we are going to talk about that, and I would like to dive into our terms right away.

[00:01:07.230] – APS’s Özge Gürcanlı Fischer Baum

Can you tell us what associative memory is and why does it typically decline with age?

[00:01:14.140] – Karen Campbell

Associative memory is your ability to form links or associations between different pieces of information. A common example that people could relate to is meeting somebody for the first time at a party. You see their face and they tell you their name. Like, Hi, my name is Karen. Forming that link between my face and the name Karen is an example of associative memory. This type of memory, it’s like the basic building block of higher-order memories, like our memories for more complex events. When you go to a party and you meet me, and you’re also trying to associate all these other little pieces of information into one big event or episodic memory, your memory for that whole experience relies on your ability to form these links between different pieces of information. We know that memory for events becomes slightly less accurate as people get older. One of the explanations for that is that older adults are poor at forming these links between different pieces of information. Now, the why that is the case, I would argue, is still an open question. We’re still looking into what exactly is causing that.

[00:02:31.610] – APS’s Özge Gürcanlı Fischer Baum

Yeah, we will talk more about that. Can you tell our listeners about the traditional view on how old the adults experience difficulties with associated memory?

[00:02:42.660] – Karen Campbell

Yeah. The traditional view or one of the most popular theories is the associative deficit hypothesis of aging, put forth by Mosha Naba Benjamin. This view is that with age, our ability to form those links or those associations declines. It’s been suggested that older adults have trouble with the binding mechanism in memory. That is the mechanism that links these different pieces of information together. Then they go on to suggest that this underlies higher order memory problems with, say, event memory. Then because older adults aren’t really linking those pieces of information together, like my face and the name Karen, that’s why you’re not able to recall those associations later on.

[00:03:29.500] – APS’s Özge Gürcanlı Fischer Baum

Yeah. The general claim is that there’s a problem in linking those things. In your article, you talk about the hyperbinding hypothesis. What is it? Does it explain increased forgetting in older adults?

[00:03:44.730] – Karen Campbell

Well, we certainly think that it does. The hyperbinding hypothesis suggests that older adults are actually forming too many associations. It’s not that this binding mechanism is necessarily impaired with age, or maybe it is But also on top of that, what’s happening is they’re forming too many associations. It’s building on a long line of work, a lot of it done by Lynn Hacher and Rose Zacks and this inhibitory deficit theory of aging, which shows that older adults are less able to ignore distracting information. Any one given moment in time, they don’t just have in mind the things that they’re trying to pay attention to, what in cognitive psychology, we often call target information, but they also are attending to these distractors in the environment. That leads them to have excess information in working memory in a given moment. Since things that are in working memory or within the focus of attention at the same time have been shown to be automatically bound together, that binding process is just happening automatically on whatever you happen to be co-attending, the idea that Lynn and I had, Lynn My question I had was that because Older Adults have all this extra information in mind, they might actually be forming too many associations, too many non-target associations between this distracting information and whatever they want to be paying attention to.

[00:05:16.830] – Karen Campbell

In the first study in which we showed this, which came out in 2010 in psychscience, we set out to test this hypothesis. We had older and younger adults doing a task that involved them paying attention to pictures. Over top of the pictures were these irrelevant word stimuli. We said, Don’t pay attention to those words. Only pay attention to the pictures. They did that cover task for a little while. Then we had a failed interval, and then we wanted to measure memory for those target-distracted pairs. We now showed them these picture-word pairs again, but on this newt, and we wanted them to learn this for this paired associate learning task. That’s where you are going to say, I want you to study these pairs of pictures and words, and then I’m going to show you the picture alone and ask you to recall the word that went with it. But importantly on this task, some of those pairs were preserved. They’re the same as they had seen before on the one back task. Some were brand new pictures and words, and some were disrupted. They were made up of familiar things, but now we’ve mixed the associations around.

[00:06:27.790] – Karen Campbell

The surprising finding that we saw was that older adults showed a memory advantage for pairs that were kept the same, for target-distractor pairs that were kept the same from the one back task versus ones that were re-arranged, suggesting that they had inadvertently formed these associations between those pairs earlier on, and now it’s giving a boost to them in memory on this later task. But also for the disrupted pairs, it made them do worse relative to new pairs. So suggesting that in that case, Having learned something earlier that now is irrelevant is getting in the way of your ability to learn something else using those same materials. So that was the first study where we showed that older adults are forming these non-targeted associations. They’re hyperbinding. Then that can lead to this interference effect in memory. It can get in the way of your memory later on.

[00:07:25.330] – APS’s Özge Gürcanlı Fischer Baum

Yeah. Let’s talk about that a little bit. What I hear is that The linking mechanism is not broken. What is happening rather is that all the redalls are forming too many associations and they get in the way.

[00:07:40.640] – Karen Campbell

Yes, that’s our view.

[00:07:45.270] – APS’s Özge Gürcanlı Fischer Baum

Before we move on, let’s talk about implicit and explicit memory a little bit. What is the main difference between the two, according to you?

[00:07:57.200] – Karen Campbell

Explicit memory is memory that you are consciously aware of and that you’re intentionally trying to recall. For instance, if I showed you a list of words to remember, and then later I asked you to recall all those words that you had seen earlier on, it involves some conscious effort. Or I could show you another list of words. Some of them are old and some are new words, and you have to differentiate between them. Tell me which ones you saw before and which ones are new. In these cases, you’re using this effort full conscious retrieval process. Whereas implicit memory is unconscious and it’s retrieved without effort. It’s inferred based on your performance. For instance, like riding a bike or if you’re playing a musical piece on the piano and you’re playing it the first time and then you try playing it the second time and you speed up the second time because you’ve learned it, that’s really a form of implicit memory. You’re showing improved performance on on the second occurrence because you have some memory somewhere in the system, but you’re not necessarily consciously trying to recall it. Usually in memory tests in the lab, it’s measured indirectly.

[00:09:13.660] – Karen Campbell

Back to the word list example, if I gave you a list of words to remember, and then later I gave you some word fragments. Some of the letters are there and some are missing, like when you’re doing a crossword puzzle. I asked you to recall the first just Solve it with the first word that comes to mind. You’re more likely to produce words that you saw on that earlier word list than you would be if you hadn’t seen them in the experiment that day. That’s an example of priming. It’s influencing your memory, it’s influencing your performance, but you’re not exactly consciously aware of it.

[00:09:53.210] – APS’s Özge Gürcanlı Fischer Baum

Yeah, great explanation. Thank you so much. Basically, the main difference is unconscious versus conscious way of engaging with tasks. Of course, because of that, they come with different task types when psychologists test about them. Now, I’m ready to ask my next question. Your paper discusses that hyperbinding effects are more apparent on other implicit test conditions. Why do you think that is the case?

[00:10:19.350] – Karen Campbell

We’ve tested, can older adults tell us, if we ask, show them the pictures again and we say, what were the distracting words shown with each of these pictures. They can’t report them. Or even if we say, You saw some of these before. Now, let’s test your memory for them. That interferes with that hyperbinding effect. We think that that comes down to the fact that when we try to remember something intentionally, it can get in the way of our implicit memory for something. So think of when you’re like, my example is like, I have a code to my office door and I can input it when I’m at my office door and not thinking about it. But if you ask me what the code was when I’m not around my door or if I actually start to think about it too much when I’m inputting it, I can’t really remember the code. And that’s a perfect example of your effortful controlled retrieval attempts getting in the way of what you know implicitly or procedurally. The same thing can happen in memory experiments. Memory researchers have for a long time that if you want to test implicit memory, you need to be a little bit deceitful.

[00:11:36.330] – Karen Campbell

You need to hide the fact that it’s a memory test and say, We just for you to do these word fragments. We’re not measuring memory. Because as soon as people think that their memory is being tested. They start trying to remember those words they saw. You have contamination of your implicit memory by explicit retrieval. Now, sometimes it might help. You might think of some words you wouldn’t have thought of otherwise, but in some cases, it might get in the way of what you would have shown us that you know if you hadn’t started trying to remember. In these hyperbinding studies, we’re trying to test these probably relatively weak associations between targets and distractors. You weren’t supposed to pay attention to these associations in the first place. It was probably a pretty weak association. We need these highly sensitive memory tests. And implicit memory tests are very sensitive. I could give you several examples of studies where we’ll show implicit memory for things years later. I think there was something recently, like 30, 35 years later, like reading upside down, being faster for a text you saw before versus a brand new text. So they’re very sensitive.

[00:12:55.940] – Karen Campbell

And so they can show us if people are remembering these non-target associations But when we ask people to try to explicitly recall the distractor that they had seen, we think that maybe their attempts are getting in the way. Like they saw a picture of a cabbage earlier, and now they’re ending up thinking about cool slough, or they’re thinking about some other, which would be a semantically related associate for a coverage, or they might think of another target they had seen at encoding. This is now interfering and getting in the way with their ability to show us their implicit memory for that weak non-target association. But this is just a hypothesis. That was one of the new developments in this current directions paper. I was trying to address this issue, but it’s going to require more empirical work.

[00:13:50.460] – APS’s Özge Gürcanlı Fischer Baum

Yeah, but the evidence you provide so far is interesting and definitely intriguing for us. Let me ask you a little We’ve talked about what else we know about binding in general. What do we currently know about the neural mechanisms underlying hyperbinding? Are there specific brain regions implicated in this process?

[00:14:14.880] – Karen Campbell

That’s a good question. I think that we still don’t know too much about what regions in the brain are responsible for this binding. We might assume that it’s relying on the medial temporal lobes, which are usually We respond structures like the hippocampus that are typically associated with binding. But we don’t know if this associative memory is happening in other cortical areas. But Audrey Darte has done some very clever EEG studies, looking at neural underpinnings or neural associates of these effects. And they’ve shown that in a different paradigm where they have a central object and flanked on either side by two contexts, like a color and a scene, and people are told to attend to either one or the other, they show that the degree to which they can use the EEG activity, scalp activity, to decode the target context, so the context people are supposed to pay attention to, that relates to better memory for the target and worse memory for the distractor later on. They also show that if you’re The ability to decode that target context falls off very quickly, especially in older adults, so as if their attention was shifting from the target to the distractor, then that relates to the degree of hyperbinding that people show.

[00:15:46.650] – Karen Campbell

But that’s not really telling us where in the brain exactly is this happening. This is probably decoding happening on surface. Maybe it’s in ocipital regions. I’m not entirely sure. And she It’s also shown using EEG that if participants have done hyperbinding at encoding, it leads to greater frontal activity at retrieval, as if it’s placing, having formed these irrelevant associations is now placing more demand on frontal control mechanisms when people go to retrieve these associations later on. Maybe in order to overcome that interference, older adults are having a call on frontal control. My PhD student, Emily Davis and I, we recently finished scanning older and younger adults using fMRI during a hyperbinding paradigm. We’re hoping to have a better understanding soon of the precise neural mechanisms that are involved in hyperbinding.

[00:16:50.190] – APS’s Özge Gürcanlı Fischer Baum

Yeah, that’s very exciting. Let us know when you know more, and we would love to talk more about that, too, when you have the data. Yeah, What do you think the broader implications of the hyperbinding hypothesis are for understanding everyday memory challenges in older adults?

[00:17:10.980] – Karen Campbell

To me, it suggests that a major cause of age-related forgetting is learning too much. It flips the old adage on its head and says, It’s not that they can’t learn these associations. It’s like they might actually be forming too many them. It challenges a common assumption that the ability to form associations decreases with age, because it really seems to be that it’s explicit access to those associations. That’s the problem. When it comes to trying to develop interventions aimed at improving memory in older adults, we might be chasing up the wrong tree or barking up the wrong tree, chasing up the wrong mechanism. We need to focus on improving people’s attentional control rather than the binding process per se, at least in normal healthy aging. I’m not speaking for necessarily the development of dementia or things like that.

[00:18:16.870] – APS’s Özge Gürcanlı Fischer Baum

The first study you mentioned answers this, right? If we can manage to direct their attention to not to pay attention to too many things so they can perform better. Yeah, that is very interesting. I definitely learned something new today. Thank you so much. Is there anything else that you would like to share with our listeners?

[00:18:39.410] – Karen Campbell

I guess the main points for improving your memory as you get older, and for young people, is to try to minimize distraction. My new thing is, put your phone down. Your phone is a constant… I’ve been chasing up recent research on this, and older adults are guilty of smartphone use, too, when they’re supposed to be doing other things. So put the phone down or try to minimize distraction in cases when you really need to attend to something. Another important thing is to do things at your optimal time of day. Cindy May has a lot of work showing that our time of day preferences shift as we get older, and older adults tend to be more like morning people. So if you really need to attend to something, like going to your doctor’s appointment, something like that, you should do it in the morning. I think most older adults already know this. They already do this. We’re not telling them anything new there. When we ask them to come into the lab for memory experiments, they almost always want to come in the morning when they know they’re going to be fresh. But I think that those would be my top tips to try to minimize unwanted hypervining.

[00:19:52.500] – APS’s Özge Gürcanlı Fischer Baum

Yeah, great. Great suggestions. I took some notes for myself and for my mom also. So Karen, this was a pleasure. Thank you very much for joining us today.

[00:20:05.160] – Karen Campbell

Thanks for having me. Very nice to meet you.

[00:20:09.570] – APS’s Özge Gürcanlı Fischer Baum

This is Özge Gürcanlı Fischer Baum with APS, and I have been speaking to Karen Campbell from Brock University. If you want to know more about this research, visit psychologilscience.org. Would you like to reach us? Send us your thoughts and questions at [email protected].