Why we forget and how to.., p.15
Why We Forget and How to Remember Better, page 15
If you reread the words that were presented, you can probably guess as to why this experiment leads to memory errors. The words you read were all closely associated with those non-presented words. In fact, the words you read were chosen specifically because they are strongly associated with the non-presented words. They represent the gist or general theme of the list. The words chair, sleep, or sweet might have even sprung to mind as you were reading the list of words—which would also cause these non-presented words to feel highly familiar to you if they came to mind when you were recalling the list. Moreover, when we asked you for the words, we tried to push you toward recalling as many of them as possible. We told you there were 25 words on the list because we know that most people won’t be able to remember all 25 words, and knowing that you’re “coming up short” can push you to accept as a memory whatever content springs to mind. This tendency is one reason why it is important that eyewitnesses are reminded that the perpetrator may not be in the lineup.
Inferring Truth from Familiarity
Answer quickly: What does a cow drink? The answer is of course water, but if your first thought was “milk,” you aren’t alone. Because milk is a beverage that we associate with cows, it will spring to mind quickly for many of us. Elizabeth does this demonstration aloud in class, asking students to shout out the answer as fast as they can: The first shouts are almost always “milk,” and only a little later is “water” heard. When you’re trying to respond quickly, it’s easy to assume that the information that pops easily into your mind is accurate.
Another example of this tendency to accept information that pops into your head as accurate is the illusory truth effect. This phenomenon describes the tendency to trust information that you’ve heard multiple times. This inclination to believe repeated information can be important for your ability to learn—a teacher might misspeak once, but they probably won’t consistently generate wrong information—and children learn the association between repetition and truth by the time they are school-aged. But where this tendency pivots from being beneficial to damaging is that it continues to operate even if you’ve been warned that the information is coming from an unreliable source and even if you’ve been directly told the information is false. This phenomenon can be exploited by everyone from advertisers to politicians. It is particularly problematic on social media, a mode of communication that encourages superficial thinking (as you scan from one posting to another) and motivates the repetition and sharing of content.
With his colleagues Jason Mitchell and Dan Schacter, Andrew examined this illusory truth effect in older adults and individuals with Alzheimer’s disease.8 The participants in this experiment studied 44 ambiguous statements that were randomly assigned “true” or “false” labels, such as, “It takes 32 coffee beans to make a cup of espresso: FALSE,” and “It takes 4 hours to hard boil an ostrich egg: TRUE.” When participants were then asked which statements were true, healthy older adults correctly identified 77% of the true statements as being true, but they also identified 39% of the false statements as being true. Although this result is startling in itself, the Alzheimer’s results are even more so. Individuals with Alzheimer’s disease correctly identified 69% of the true statements as being true, but also identified 59% of the false statements as being true—more than the half you’d expect them to identify if they were just guessing. This means that if you tell an individual with Alzheimer’s that some information isn’t true, they may be more likely to remember that the information is true than if you didn’t say anything at all. The bottom line is that you should never tell an individual with Alzheimer’s what isn’t true (“Don’t take your medicine after dinner”)—just tell them what is true (“Take your medicine on an empty stomach”).
What About the Accuracy of Emotional Memories?
At this point in the chapter, you may be thinking, “Well, sure, memories aren’t always perfect, but there are some events that are forever etched in my memory, and I know that they are accurate.” Perhaps it’s your first kiss, the moment you first held your child in your arms, where you were when you first learned that John F. Kennedy was assassinated, who you were with when you saw the towers fall in the September 11, 2001, attacks, or what you were doing when you heard the 2016 election results. Many people are confident in their memory for these types of events—even when they happened decades ago—and you may feel like you are re-experiencing those moments as you recall them. The term “flashbulb memory” was coined in 1977 by two memory researchers from Harvard, Roger Brown and James Kulik, to describe the vivid way in which highly surprising, emotional, and important events seem to sear themselves into our memories—as if a flash photograph were taken, forever imprinting details of the event.
Picture-Perfect?
It turns out that emotional memories are not picture-perfect; they’re actually prone to all the same types of distortions as other memories. Even Brown and Kulik recognized that it was not appropriate to consider emotional memories as like photographs in all respects, stating, “An actual photograph, taken by flashbulb, preserves everything within its scope; it is altogether indiscriminate. Our flashbulb memories are not.” They go on to describe how, although they have vivid memories of where they were when they learned of the assassination of JFK, details are missing. For instance, they note that Brown “faced a desk with many objects on it, and some kind of weather was visible through the window, but none of this is in his memory picture.”9
Confidence, Not Consistency
Although there can be some situations when emotional memories are remembered with better detail than more mundane experiences, what is most remarkable about memories for situations that evoke emotion is how vivid those memories feel to us and how confident we are about their accuracy—even when we’re wrong. In one of the first demonstrations of this disconnect between confidence and accuracy for an emotional event, Ulrich Neisser and Nicole Harsh at Emory University asked college students to report the circumstances in which they learned about the explosion of the space shuttle Challenger.10 Months later, they were asked to again report those circumstances and to rate their confidence in their memory. Participants gave detailed reports at both timepoints, and were highly confident in their memory’s accuracy, yet many details were inconsistent. This disconnect between confidence and accuracy (or, at least, consistency) in emotional memories has since been demonstrated for many different public events, leading Jennifer Talarico and David Rubin at Duke University to publish a paper with the title “Confidence, Not Consistency, Characterizes Flashbulb Memories.”11
Rehearsal Boosts Confidence
As noted by Ken Paller at Northwestern University, one reason for this disconnect between confidence and accuracy may relate to how frequently we think about past emotional experiences.12 We reflect on these events and discuss them with others. Each time, we build a memory structure for the event. After so much rehearsal, the construction process begins to feel effortless, and the structure created seems like a replica of the original event. But in reality, each of those rebuildings provides an opportunity for us to misplace or omit a block, to incorporate erroneous content from someone else’s comments, or to morph our structure based on knowledge we learned after the fact.
Remembering the Threat
Another reason for this disconnect between confidence and accuracy may be that there is some, relatively small, subset of details that we may remember extremely well from an emotional event. The weapon focus effect describes how individuals have more trouble identifying a suspect, and have more false identifications, if a weapon is visible.13 This isn’t simply because people don’t see the other details.14 It’s as if all the brain’s resources are being devoted toward building that threat (whether a gun, knife, or menacing fist) into the memory structure and other details (like the perpetrator’s face or clothing) are inadequately constructed. Later, if we are asked to think about the event as a whole, we may feel like we have a vivid memory because of the select portions that are so crisply retained. It’s as if we’re standing in one room of our memory structure, marveling at the gilded relief in which some details are portrayed, without realizing that the corridors that should have led to other details have crumbled.
Protecting Against False Memories
What can you do to defend yourself against false memories? The most important piece of advice is: If the stakes are high, take the time to monitor your memory. After content has come to mind, consider why that content might have come to mind, and evaluate whether it is the right content. Ask yourself the following questions:
• Why is the information familiar? Just because information comes to mind easily, that doesn’t always mean it is accurate. You now know you’re more likely to trust information that you’ve heard multiple times, that you can be susceptible to the influences of misinformation, and that you can generate erroneous information when it’s consistent with the gist of an event. So, before you act on the information coming to mind, take a moment to evaluate why that content is springing to your consciousness. You may realize it’s likely a false memory.
• Could it have happened that way? Take a moment to think about the details you recall about the memory. Are they consistent with one another? Or is one detail mutually exclusive of another (such as cousin Suzy and your daughter both being at the same Thanksgiving dinner). This is a strategy called recall-to-reject;15 as the wording implies, the recall of one piece of information from your memory can help you to reject some other information as being a false memory.
• How well should you remember this content? If someone tells you you’ve eaten at a neighborhood restaurant before, you might accept their claim as true if you eat out a lot and, after a while, the meals all blur together. But if you would have dined at the restaurant in question only on a special occasion, then you probably should suggest to the person that they may have you confused for someone else. In other words, if an event would have been distinctive, then you should be more likely to take the lack of a strong memory as evidence that it didn’t occur.
Part 3
When there is too little memory—or too much
13
Just normal aging—or is it Alzheimer’s disease?
“I’m so worried about my memory,” says the 82-year-old accountant and mother of three. “All of my friends are having memory problems. Many of them have dementia, and some even have Alzheimer’s disease. I think I’m getting it too—I know I am. This morning I walked into my bedroom and could not remember what I was looking for—not until I walked back down to the chilly basement and remembered the sweater I had gone to get. And coming up with people’s names, forget it! If I don’t see someone regularly, I have a terrible time recalling their name. That’s not all. Last week, I was driving to the bank while my son was telling me about the grandchildren—they’re all doing so well—and the next thing I know I’m in the parking lot of the grocery store. I had no recollection of the driving for the last 10 minutes nor how I ended up at the grocery store instead of the bank.”
Is this 82-year-old accountant developing Alzheimer’s disease or aging normally? In this chapter we will review the changes in memory that occur with normal aging as well as brain disorders of aging such as Alzheimer’s disease so that you will be able to tell them apart. We’ll also discuss how you can use the other memory systems that are relatively intact to compensate for some of the memory problems that occur in normal aging and various brain disorders.
Normal Aging
Individuals who are aging normally in their 60s, 70s, and 80s experience some difficulty keeping information in mind in their working memory (see Chapter 3). They also need to use more effort to learn new information and to retrieve information when they need it from their episodic memory (see Chapter 4), and they have trouble recalling people’s names from their semantic memory (see Chapter 5). Experiencing these memory challenges with increased frequency as you age does not need to be cause for alarm. We’ll examine these difficulties, and then turn to procedural memory (see Chapter 2), which is relatively preserved in aging.
Older Frontal Lobes
Memory difficulties in normal aging often are related to changes that occur to the frontal lobes and their connections to the rest of the brain. Older frontal lobes just don’t function as well as they did when they were younger. Some researchers and clinicians believe this is due to a small amount of age-related damage to this part of the brain and its connections from tiny strokes or other pathology (we’ll review strokes later on in this chapter). Other researchers believe these changes to the frontal lobes are due to normal, physiologic changes not related to a disorder, such as an alteration in the prevalence of brain cell receptors that facilitates the stabilization of memories at the cost of diminishing the ability to form new memories.
Working Memory in Normal Aging
Recall that the prefrontal cortex is the central executive of the working memory system. Since frontal lobe function decreases with aging, it should not surprise you that older adults show diminished working memory abilities relative to younger adults. Compared to those in their 20s and 30s, older adults generally cannot keep as much information in mind or manipulate it as easily. This means that, compared to when they were younger, older adults are usually slower to add up a column of numbers in their head and less able to keep in mind a map of a city they are visiting for the first time.
Episodic Memory in Normal Aging
There are three major changes that occur in episodic memory as people age, all related to their diminished frontal lobe function. We’ll consider them each in turn, along with some simple measures you can take to compensate for these changes.
First, it takes more effort to pay attention and thus to get the desired information into episodic memory. Simply repeating information, however, can help you overcome this difficulty. So, try repeating your shopping list, an address you are driving to, or the day’s agenda a couple of times in order to remember them.
Second, it takes more time, effort—and often some strategies—to get the desired information out of episodic memory. With diminished frontal lobe function, your ability to search through your episodic memory to find and rebuild the memory you’re looking for is diminished. Sometimes just concentrating hard and giving yourself a bit of time is enough for the desired memory to come to mind. At other times you will need to use strategies to bring the desired memory to mind. Try to recall the location in which the memory was formed—that cue might trigger recall of the memory. See Chapter 9 and Part 5 for many more suggestions on how to improve your memory retrieval.
Third, older adults are more likely to experience a mixed-up, distorted, or outright false memory. Although these types of memory mix-ups can happen to anyone, because frontal lobe function declines as we age, false memories are more likely to occur to older adults. As we discussed in Chapter 12, you can reduce false memories by paying close attention to the details of information when you are learning them and trying again to picture as many specific details as you can when you are retrieving the information.
Semantic Memory in Normal Aging
Most healthy older adults experience some difficulty retrieving people’s names or the titles of books or movies. There are two reasons for this difficulty. The first is their frontal lobe dysfunction. It is your frontal lobes that help you search through your stores of semantic knowledge to retrieve the specific information you’re looking for. So, because of frontal lobe dysfunction, it may be more difficult for older adults to retrieve any type of knowledge. But why are people’s names specifically difficult for older adults? We believe it is likely related to the shrinkage that so often occurs in aging to the tip of the temporal lobe—the very place where the names of people are usually stored. One way to improve your retrieval of people’s names is to think about other things you know about the individual: their occupation, hobbies, family, appearance, and so forth. See Chapter 24 for additional suggestions on how to improve your retrieval of names.
Procedural Memory in Normal Aging
One aspect of memory that is generally preserved in individuals who are aging normally is procedural memory, the ability to learn and use skills and habits. This means that if you always wanted to take up golf (or baseball or snowshoeing) but never had the time while you were working, and you are now retired and in your 60s, 70s, or 80s, there is no reason that you cannot take lessons and begin to learn the new sport. Just remember that, like any activity at any age, it may take a number of years of practice before you are proficient (hopefully a little sooner for snowshoeing).
Equally if not more importantly, you can also use your procedural memory to compensate for difficulties in your episodic memory. For example, perhaps when you were younger you could leave your keys anywhere and always be able to find them. Now that you’re older, you notice that you’re hunting around the house for your keys daily. If you use your procedural memory to train yourself to get into the habit of always leaving your keys in the same place, you’ll always be able to find them when you need them.
Upsides to an Aging Memory System
Although older adults often notice their increased memory difficulties, there are also benefits to the way that older adults’ brains record information. While younger adults’ brains may be drafting memory structures with lots of details—some of them unimportant—older adults’ memory structures are more likely to include just the essential elements. Remembering just the critical information can make it easier for older adults to avoid the common pitfall of “missing the forest for the trees,” allowing them to grasp the overall importance of a situation. The way older adults’ brains build memory structures can also make it easier for them to see commonalities between different situations and to understand how knowledge acquired in one context can be applied to the situation at hand. In fact, some of the wisdom that comes with aging may be attributable to changes in the way the aging brain builds its memory structures.
