Memory Errors

chapter 8 Remembering Complex

Events

 

Memory Errors, Memory Gaps Where did you spend last summer? What country did you grow up in? Where were you five minutes ago? These are easy questions, and you effortlessly retrieve this information from memory the moment you need it. If we want to understand how memory functions, therefore, we need to understand how you locate these bits of information (and thousands of others just like them) so readily.

But we also need to account for some other observations. Sometimes, when you try to remember an episode, you draw a blank. On other occasions, you recall something, but with no certainty that you’re correct: “I think her nickname was Dink, but I’m not sure.” And sometimes, when you do recall a past episode, it turns out that your memory is mistaken. Perhaps a few details of the event were different from the way you recall them. Or perhaps your memory is completely wrong, misrepresenting large elements of the original episode. Worse, in some cases you can remember entire events that never happened at all! In this chapter, well consider how, and how often, these errors arise. Let’s start with some examples. Memory Errors: Some Initial Examples In 1992, an El Al cargo plane lost power in two of its engines just after taking off from Amsterdam’s Schiphol Airport. The pilot attempted to return the plane to the airport but couldn’t make it. A few minutes later, the plane crashed into an 11-story apartment building in Amsterdam’s Bijlmermeer neighborhood. The building collapsed and burst into flames; 43 people were killed, including the plane’s entire crew.

Ten months later, researchers questioned 193 Dutch people about the crash, asking them in particular, “Did you see the television film of the moment the plane hit the apartment building?” More than half of the participants (107 of them) reported seeing the film, even though there was no such film. No camera had recorded the crash; no film (or any reenactment) was shown on television. The participants seemed to be remembering something that never took place (Crombag, Wagenaar, & van Koppen, 1996).

In a follow-up study, investigators surveyed another 93 people about the plane crash. These people were also asked whether they’d seen the (nonexistent) TV film, and then they were asked detailed questions about exactly what they had seen in the film: Was the plane burning when it crashed, or did it catch fire a moment later? In the film, did they see the plane come down vertically or did it hit the building while still moving horizontally at a considerable with no forward speed speed? Two thirds of these participants reported seeing the film, and most of them were able to provide details about what they had When asked about the plane’s speed, for example, only 23% said that they couldn’t remember. The others gave various responses, presumably based on their “memory” of the (nonexistent) film.

Other studies have produced similar results. There was no video footage of the car crash in which Princess Diana was killed, but 44% of the British participants in one study recalled seeing the footage (Ost, Vrij, Costall, & Bull, 2002). More than a third of the participants questioned about a nightclub bombing in Bali recalled seeing a (nonexistent) video, and nearly all these participants reported details about what they’d seen in the video (Wilson & French, 2006).

It turns out that more persistent questioning can lead some of these people to admit they actually don’t remember seeing the video. Even with persistent questioning, though, many participants continue to insist that they did see the video-and they offer additional information in the film (e.g., Patihis & Loftus, 2015; Smeets et al., 2006). Also, in all about exactly what they sav these studies, let’s emphasize that participants are thinking back to an emotional and much- discussed event; the researchers aren’t asking them to recall a minor occurrence.

 

Is memory more accurate when the questions come after a shorter delay? In a study by Brewer and Treyens (1981), participants were asked to wait briefly in the experimenter’s office prior to the procedure’s start. After 35 seconds, participants were taken out of this office and told that there actually was no experimental procedure. Instead, the study was concerned with their memory for the room in which they’d just been sitting. Participants’ descriptions of the office were powerfully influenced by their prior beliefs. Surely, most participants would expect an academic office to contain shelves filled with books. In this particular office, though, no books in view (see Fiqure 8.1). Even so, almost one third of the participants (9 of 30) reported seeing books in the office. Their recall, in other words, was governed by their expectations, not by reality. How could this happen? How could so many Dutch participants be wrong in their recall of the plane crash? How could intelligent, alert college students fail to remember what they’d seen in an office just moments earlier? Memory Errors: A Hypothesis In Chapters 6 and 7, we emphasized the importance of memory connections that link each bit of knowledge in your memory to other bits. Sometimes these connections tie together similar episodes, so that a trip to the beach ends up connected in memory to your recollection of other trips. Sometimes the connections tie an episode to certain ideas-ideas, perhaps, that were part of your understanding of the episode, or ideas that were triggered by some element within the episode.

It’s not just separate episodes and ideas that are linked in this way. Even for a single episode, the elements of the episode are stored separately from one another and are linked by connections. In fact, the storage is “modality-specific,” with the bits representing what you saw stored in brain areas devoted to visual processing, the bits representing what you heard stored in brain areas specialized for auditory processing, and so on (e.g., Nyberg, Habib, McIntosh, & Tulving, 2000; Wheeler Peterson, & Buckner, 2000; also see Chapter 7, Figure 7.4, p. 245).

 

With all these connections in place-element to element, episode to episode, episode to related ideas-information ends up stored in memory in a system that resembles a vast spider web, with was the each bit of information connected by many threads to other bits elsewhere in the web. This idea that in Chapter 7 we described as a huge network of interconnected nodes. However, within this network there are no boundaries keeping the elements of one episode separate from elements of other episodes. The episodes, in other words, aren’t stored in separate “files,” each distinct from the others. What is it, therefore, that holds together the various bits within each episode? To a large extent, it’s simply the density of connections. There are many connections linking the various aspects of your “trip to the beach” to one another; there are fewer connections linking this event to other events.

 

As we’ve discussed, these connections play a crucial role in memory retrieval. Imagine that you’re trying to recall the restaurant you ate at during your beach trip. You’ll start by activating nodes in memory that represent some aspect of the trip-perhaps your memory of the rainy weather. Activation will then flow outward from there, through the connections you’ve established, and this will energize nodes representing other aspects of the trip. The flow of activation can then continue from there, eventually reaching the nodes you seek. In this way, the connections serve as retrieval paths, guiding your search through memory.

 

Obviously, then, memory connections are a good thing; without them, you might never locate the information you’re seeking. But the connections can also create problems. As you add more and more links between the bits of this episode and the bits of that episode, you’re gradually knitting these two episodes together. As a result, you may lose track of the “boundary” between the episodes. More precisely, you’re likely to lose track of which bits of information were contained within which event. In this way, you become vulnerable to what we might think of as “transplant” errors, in which a bit of information encountered in one context is transplanted into another context. In the same way, as your memory for an episode becomes more and more interwoven with other thoughts you’ve had about the event, it will become difficult to keep track of which elements are were actually part of the episode itself, and which are linked merely because they were associated with the episode in your thoughts. This, too, can produce linked to the episode because they transplant errors, in which elements that were part of your thinking get misremembered as if they were actually part of the original experience. Understanding Both Helps and Hurts Memory It seems, then, that memory connections both help and hurt recollection. They help because the connections, serving as retrieval paths, enable you to locate information in memory. But connections can hurt because they sometimes make it difficult to see where the remembered episode stops and other, related knowledge begins. As a result, the connections encourage intrusion errors-errors in which other knowledge intrudes into the remembered event.

 

To see how these points play out, consider an early study by Owens, Bower, and Black (1979). In this study, half of the participants read the following passage:

 

 

Nancy arrived at the cocktail party. She looked around the room to see who was there. She went to talk with her professor. She felt she had to talk to him but was a little nervous about just what to say. A group of people started to play charades. Nancy went over and had some refreshments. The hors d’oeuvres were good, but she wasn’t interested in talking to the rest of the people at the party. After a while she decided she’d had enough and left the party.

Other participants read the same passage, but with a prologue that set the stage:

Nancy woke up feeling sick again, and she wondered if she really was pregnant. How would she tell the professor she had been seeing? And the money was another problem.

 

 

All participants were then given a recall test in which they were asked to remember the sentences as exactly as they could. Table 8.1 shows the results-the participants who had read the prologue (the Theme condition) recalled much more of the original story (i.e., they remembered the propositions actually contained within the story). This is what we should expect, based on the claims made in Chapter 6: The prologue provided a meaningful context for the remainder of the story, and this helped understanding. Understanding, in turn, promoted recall.

 

 At the same time, the story’s prologue also led participants to include elements in their recall that weren’t mentioned in the original episode. In fact, participants who had seen the prologue made four times as many intrusion errors as did participants who hadn’t seen the prologue. For example, they might include in their recall something like “The professor had gotten Nancy pregnant.” This idea isn’t part of the story but is certainly implied, so will probably be part of participants’ understanding of the story. It’s then this understanding (including the imported element) that is remembered. The DRM Procedure Similar effects, with memory connections both helping and hurting memory, can be demonstrated with simple word lists. For example, in many experiments, participants have been presented with lists like this one: “bed, rest, awake, tired, dream, wake, snooze, blanket, doze, slumber, snore, nap, peace, yawn, drowsy.” Immediately after hearing this list, are asked to recall as many of participants the words as they can.

 

As you surely noticed, the words in this list are all associated with sleep, and the presence of this theme helps memory: The list words are easy to remember. It turns out, though, that the word “sleep” is not itself included in the list. Nonetheless, research participants spontaneously make the connection between the list words and this associated word, and this connection almost always leads to a memory error. When the time comes for recall, participants are extremely likely to recall that they heard “sleep.” In fact, they’re just as likely to recall “sleep” as they are to recall the actual words on the list (see Figure 8.2). When asked how confident they are in their memories participants are just as confident in their (false) recall of “sleep” as they are in their (correct) memory of genuine list words (Gallo, 2010: for earlier and classic papers in this arena. see Deese, 1957; Roediger & McDermott, 1995, 2000). This experiment (and many others like it) uses the DRM procedure, a bit of terminology that honors the investigators who developed it (James Deese, Henry Roediger II, and Kathleen McDermott). The procedure yields many errors even if participants are put on their guard before the procedure begins-that is, told about the nature of the lists and the frequency with which they produce errors (Gallo, Roberts, & Seamon, 1997; McDermott & Roediger, 1998). Apparently, the mechanisms leading to these errors are so automatic that people can’t inhibit them. Schematic Knowledge Imagine that you go to a restaurant with a friend. This setting is familiar for you, and you have some commonsense knowledge about what normally happens here. You’ll be seated; someone will bring menus; you’ll order, then eat; eventually, you’ll pay and leave. Knowledge like this is often referred to with the Greek word schema (plural: schemata). Schemata summarize the broad pattern of what’s normal in a situation-and so your kitchen schema tells you that a kitchen is likely to have a stove but no piano; your dentist’s office schema tells you that there are likely to be magazines in the waiting room, that you’ll probably get a new toothbrush when you leave, and so on.

 

Schemata help you in many ways. In a restaurant, for example, you’re not puzzled when someone keeps filling your water glass or when someone else drops by to ask, “How is everything?” Your schema tells you that these are normal occurrences in a restaurant, and you instantly understand how they fit into the broader framework. Schemata also help when the time comes to recall how an event unfolded. This is because there are often gaps in your recollection-either because you didn’t notice certain things in the first place, or because you’ve gradually forgotten some aspects of the experience. (We’ll say more about forgetting later in the chapter.) In either case, you can rely on your schemata to fill in these gaps. So, in thinking back to your dinner at Chez Pierre, you might not remember anything about the menus. Nonetheless, you can be reasonably sure that there were menus and that they were given to you early on and taken away after you placed your order. On this basis, you’re likely to include menus within your “recall” of the dinner, even if you have no memory of seeing the menus for this particular meal. In other words, you’ll supplement what you actually remember with a plausible reconstruction based on your schematic knowledge. And in most cases this after-the-fact reconstruction will be correct, since schemata do, after all, describe what happens most of the time. Evidence for Schematic Knowledge Clearly, then, schematic knowledge helps you, by guiding your understanding and enabling you to reconstruct things you can’t remember. But schematic knowledge can sometimes hurt you, by promoting errors in perception and memory. Moreover, the types of errors produced by schemata are quite predictable. As an example, imagine that you visit a dentist’s office, and this one happens not to have any magazines in the waiting room. It’s likely that you’ll forget this detail after a while, so what will happen when you later try to recall your trip to the dentist? Odds are good that you’ll rely on schematic knowledge and “remember” that there were magazines (since, after all, there usually are some scattered around a waiting room). In this way, your recollection will make this dentist’s office seem more typical, more ordinary, than it actually was. Here’s the same point in more general terms. We’ve already said that schemata tell you what’s typical in a setting. Therefore, if you rely on schematic knowledge to fill gaps in your recollection, you’ll fill those gaps with what’s normally in place in that sort of situation. As a result, any reliance on schemata will make the world seem more “normal” than it really is and will make the past seem more “regular” than it actually was.

 

This tendency toward “regularizing” the past has been documented in many settings. The classic demonstration, however, comes from studies published long ago by British psychologist Frederick Bartlett. Bartlett presented his participants with a story taken from the folklore of Native Americans (Bartlett, 1932). When tested later, the participants did reasonably well in recalling the gist of the story, but they made many errors in recalling the particulars. The pattern of errors, though, was quite systematic: The details omitted tended to be ones that made little sense to Bartlett’s British participants. Likewise, aspects of the story that were unfamiliar were often changed into aspects that were more familiar; steps of the story that seemed inexplicable were supplemented to make the story seem more logical.

Overall, then, the participants’ memories seem to have “cleaned up” the story they had read- making it more coherent (from their perspective), more sensible. This is exactly what we would expect if the memory errors derived from the participants’ attempts to understand the story and with that, their efforts toward fitting the story into a schematic frame. Elements that fit within the frame remained in their memories (or could be reconstructed later). Elements that didn’t fit dropped out of memory or were changed. the same spirit, consider the Brewer and Treyens study mentioned at the start of this chapter- the study in which participants remembered seeing shelves full of books, even though there were none. This error was produced by schematic knowledge. During the event itself (while the participants were sitting in the office), schematic knowledge told the participants that academic offices usually contain many books, and this knowledge biased what the participants paid attention to. (If you’re already certain that the shelves contain books, why should you spend time looking at the shelves? This would only confirm something you already know-see Vo & Henderson, 2009.) Then, when the time came to recall the office, participants used their schema to reconstruct what the office must have contained- a desk, a chair, and of course lots of books. In this way, the memory for the actual office was eclipsed by generic knowledge about what a “normal” academic office contains.

Likewise, think back to the misremembered plane crash and the related studies of people remembering videos of other prominent events, even though there were no videos of these events. Here, too, the memory errors distort reality by making the past seem more regular, more typical, than it really was. After all, people often hear about major news events via a television broadcast or Internet coverage, and these reports usually include vivid video footage. So here, too, the past as remembered seems to have been assimilated into the pattern of the ordinary. The event as it unfolded was unusual, but the event as remembered becomes typical of its kind-just as we would expect if understanding and remembering were guided by our knowledge of the way things generally unfold. e. Demonstration 8.1: Associations and Memory Error This is a test of immediate memory. Read List 1; then close the list and try to write down, from memory, as many words as you can remember from the list. Then expand the list to read List 2, close the list, and try to write down as many of its words as you can remember. Then do the same for List 3. When you’re all done, read the material that follows.

 

HIDE

List 1 List 2 List 3

Door Nose Sour

Glass Breathe Candy

Pane Sniff Sugar

Shade Aroma Bitter

Ledge Hear Good

Sill See Taste

House Nostril Tooth

Open Whiff Nice

Curtain Scent Honey

Frame Reek Soda

View Stench Chocolate

Breeze Fragrance Heart

Sash Perfume Cake

Screen Salts Tart

Shutter Rose Pie Don’t read beyond this point until you’ve tried to recall each of the three lists!

 

Each of these lists is organized around a theme, but the word that best captures that theme included in the list. All of the words in List 1, for example, are strongly associated with the word “window” but that word is not in the list. All of the words in List 2 are strongly associated with “smell” and all in List 3 are strongly associated with “sweet”; but again, these theme words are not in the lists. In your recall of the lists, did you include seeing “window” in List 1? “Smell” in List 2? “Sweet” in List 3?

 

This procedure, described in the chapter, is called the DRM procedure, in honor of the researchers who have developed this paradigm (Deese, Roediger, and McDermott). IIn this situation, often as many as half of the people tested do make these specific errors-and with considerable confidence. Of course, the theme words are associated with the list in your memory, and it’s this association that leads many people into a memory error.

 

Perhaps you read through the material after reading the text’s description of the DRM procedure. Did you make the expected error anyway? Research suggests that these errors appear even when research participants are warned about the DRM pattern, just as you were. Did you show that pattern? Or did you manage to avoid the errors?

Demonstration adapted from McDermott, K., & Roediger, H. (1998). False recognition of associates can be resistant to an explicit warning to subjects and an immediate recognition probe. Journal of Memory and Language, 39, 508-520. See also Roediger, H., &McDermott, K. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory and Cognition, 21(4), 803-814. The Cost of Memory Errors There’s clearly a “good news, bad news” quality to our discussion so far. On the positive side, memory connections serve as retrieval paths, allowing you to locate information in storage. The connections also enrich your understanding, because they tie each of your memories into a context provided by other things you know. In addition, links to schematic knowledge enable you to supplement your perception and recollection with well-informed (and usually accurate) inference.

On the negative side, though, the same connections can undermine memory accuracy, and memory errors are troubling. As we’ve discussed in other contexts, you rely on memory in many aspects of life, and it’s unsettling that the memories you rely on may be wrong-misrepresenting how the past unfolded.

 

Eyewitness Errors In fact, we can easily find circumstances in which memory errors are large in scale (not just concerned with minor details in the episode) and deeply consequential. For example, errors in eyewitness testimony (e.g., identifying the wrong person as the culprit or misreporting how an event unfolded) can potentially send an innocent person to jail and allow a guilty person to go free.

How often do eyewitnesses make mistakes? One answer comes from U.S. court cases in which DNA evidence, not available at the time of the trial, shows that the courts had convicted people who were, in truth, not guilty. There are now more than 350 of these exonerations, and the exonerees had (on average) spent more than a dozen years in jail for crimes they didn’t commit. Many of them were on death row, awaiting execution. When closely examined, these cases yield a clear message. Some of these men and women of dishonest because convicted were informants; some because analyses of forensic evidence had been botched. But by far the most common concern is eyewitness errors. In fact, according to most analyses, eyewitness errors account for at least three quarters of these false convictions-more than all other causes combined (e.g., Garrett, 2011; Reisberg, 2014)

Cases like these make it plain that memory errors, including misidentifications, are profoundly important. We’re therefore led to ask: Are there ways to avoid these errors? Or are there ways to detect the errors, so that we can decide which memories are correct and which ones are not? Planting False Memories An enormous number of studies have examined eyewitness memory-the sort of memory that police rely on when investigating crimes. In one of the earliest procedures, Loftus and Palmer (1974) showed participants series of pictures depicting an automobile collision. Later, participants were asked questions about the collision, but the questions were phrased in different ways for different groups. Some participants were asked, for example, “How fast were the cars going when they hit each other?” A different group was asked, “How fast were the cars going when they smashed into each other?” The differences among these questions were slight, but had a substantial influence: Participants in the “hit” group estimated the speed to have been 34 miles per hour: those in the “smashed” group estimated 41 miles per hour-20% higher (see Figure 8.3). But what is critical comes next: One week later, the participants were asked in a perfectly neutral way whether they had seen any broken glass in the pictures. Participants who had initially been asked the “hit” question tended to remember (correctly) that no glass was visible; participants who had been asked the “smashed” question, though, often made this error. It seems, therefore, that the change of just one word within the initial question can have a significant effect-in this case, more than doubling the likelihood of memory error.

In other studies, participants have been asked questions that contain overt misinformation about an event. For example, they might be asked, “How fast was the car going when it raced by the barn?” when, in truth, no barn was in view. In still other studies, participants are exposed to descriptions of the target event allegedly written by “other witnesses.” They might be told, for example, “Here’s how someone else recalled the crime; does this match what you recall?”” Of course, the “other witness” descriptions contained some misinformation, enabling researchers to determine if participants “pick up” the false leads (e.g., Paterson & Kemp, 2006; also Edelson, Sharon, Dolan, & Dudai, 2011). In other studies, researchers ask questions that require the participants themselves to make up some bit of misinformation. For example, participants could be asked, “In the video, was the man bleeding from his knee or from his elbow after the fall?” Even though it was clear in the video that the man wasn’t bleeding at all, participants are forced to choose one of the two options (e.g., Chrobak & Zaragoza, 2008; Zaragoza, Payment, Ackil, Drivdahl, & Beck, 2001). These procedures differ in important ways, but they are all variations on the same theme. In each case, the participant experiences an event and then is exposed to a misleading suggestion about how the event unfolded. Then some time is allowed to pass. At the end of this interval, the participant’s memory is tested. And in each of these variations, the outcome is the same: A substantial number of participants-in some studies, more than one third-end up incorporating the false suggestion into their memory of the original event.

Of course, some attempts at manipulating memory are more successful, some less so. It’s easier, for example, to plant plausible memories rather than implausible ones. (However, memories for implausible events can also be planted-see Hyman, 2000; Mazzoni, Loftus, & Kirsch, 2001; Pezdek Blandon-Gitlin, & Gabbay, 2006; Scoboria, Mazzoni, Kirsch, & Jimenez, 2006; Thomas & Loftus, 2002.) Errors are also more likely if the post-event information supplements what the person remembers, in comparison to contradicting what the person would otherwise remember. It’s apparently easier, therefore, to “add to” a memory than it is to “replace” a memory (Chrobak & Zaragoza, 2013). False memories are also more easily planted if the research participants don’t just hear about the false event but, instead, are urged to imagine how the suggested event unfolded. In one study, participants were given a list of possible childhood events (going to the emergency room late at night; winning a stuffed animal at a carnival; getting in trouble for calling 911) and were asked to “picture each event as clearly and completely” as they could. This simple exercise was enough to increase participants’ confidence that the event had really occurred (Garry, Manning, Loftus, & Serman. 1996; also Mazzoni & Memon, 2003; Sharman & Barnier, 2008; Shidlovski, Schul. & Mayo. 2014). Even acknowledging these variations, though, let’s emphasize the consistency of the findings. We can use subtle procedures (with slightly leading questions) to plant false information in someone’s memory, or we can use a more blatant procedure (demanding that the person make up the bogus facts). We can use pictures, movies, or live events as the to-be-remembered materials. In all cases it’s remarkably easy to alter someone’s memory, with the result that the past as the person remembers it can differ markedly from the past as it really was. This is a widespread pattern, with numerous implications for how we think about the past and how we think about our reliance on our own memories. (For more on research in this domain, see Carpenter & Schacter, 2017; Cochran, Greenspan, Bogart, & Loftus, 2016; Frenda, Nichols, & Loftus, 2011; Laney, 2012; Loftus, 2017; Rich & Zaragoza, 2016. For research documenting similar memory errors in children, see, e.g., Bruck & Ceci, 1999, 2009; Reisberg, 2014.)

Are There Limits on the Misinformation Effect? The studies just described reflect the misinformation effect-a term referring to memory errors that result from misinformation received after an event was experienced. What sorts of memory errors can be planted in this way?

We’ve mentioned studies in which participants remember broken glass when really there was none or remember a barn when there was no barn in view. Similar procedures have altered how people are remembered-and so, with just a few “suggestions” from the experimenter, participants remember clean-shaven men as bearded, young people as old. and fat people as thin (e.g.. Christiaansen, Sweeney, & Ochalek, 1983; Frenda et al., 2011). It’s remarkably easy to produce these errors-with just one word (“hit” vs. “smashed”) being enough to alter an individual’s recollection. What happens, though, if we ramp up our efforts to plant false memories? Can we create larger-scale errors? In one study, college students were told that the investigators were trying to learn how different people remember the same experience. The students were then given a list of events that (they were told) had been reported by their parents; the students were asked to recall these events as well as they could, so that the investigators could compare the students’ recall with their parents’ (Hyman, Husband, & Billings, 1995).

Some of the events on the list actually had been reported by the participants’ parents. Other events were bogus-made up by the experimenters. One of the bogus events was an overnight hospitalization for a high fever; in a different experiment, the bogus event was attending a wedding reception and accidentally spilling a bowlful of punch on the bride’s family.

The college students were easily able to remember the genuine events (i.e.., the events actually reported by their parents). In an initial interview, more than 80 % of these events were recalled, but none of the students recalled the bogus events. However, repeated attempts at recall changed this pattern. By a third interview, 25% of the participants were able to remember the embarrassment of spilling the punch, and many were able to supply the details of this (entirely fictitious) episode. Other studies have shown similar results. Participants have been led to recall details of particular birthday parties that, in truth, they never had (Hyman et al., 1995); or an incident of being lost in a shopping mall even though this event never took place; or a (fictitious) event in which they were the victim of a vicious animal attack (Loftus, 2003, 2004; also see, e.g. Chrobak & Zaragoza, 2008 Geraerts et al., 2009: Laney & Loftus, 2010). Errors Encouraged through “Evidence” Other researchers have taken a further step and provided participants with “evidence” in support of the bogus memory. In one procedure, researchers obtained a real childhood snapshot of the participant (see Figure 8.4A for an example) and, with a few clicks of a computer mouse, created a fictitious picture like the one shown in Figure 8.4B. With this prompt, many participants were led to a vivid, detailed recollection of the hot-air balloon ride-even though it never occurred (Wade, Garry, Read, & Lindsay, 2002). Another study used an unaltered photo showing the participants’ second- grade class (see Figure 8.5 for an example). This was apparently enough to persuade participants that the experimenters really did have information about their childhood. Therefore, when the experimenters “reminded” the participants about an episode of their childhood misbehavior, the participants took this reminder seriously. The result: Almost 80% were able to “recall” the episode, often in detail, even though it had never happened (Lindsay, Hagen, Read, Wade, & Garry, 2004). False Memories, False Confessions

 

It is clear that people can sometimes remember entire events that never took place. They sometimes happened. They can remember emotional episodes (like being lost in a shopping mall) that never remember their own transgressions (spilling the punch bowl, misbehaving in the second grade), even though these misdeeds never occurred.

 

One study pushed things still further, using a broad mix of techniques to encourage false memories (Shaw & Porter, 2015). The interviewer repeatedly asked participants that (supposedly) she had learned about from their parents. She assured participants that she had detailed information about the (fictitious) event, and she applied social pressure with comments like to recall an event “Most people are able to retrieve lost memories if they try hard enough.” She offered smiles and encouraging nods whenever participants showed signs of remembering the (bogus) target events. If participants couldn’t recall the target events, she showed signs of disappointment and said things like “That’s ok. Many people can’t recall certain events at first because they haven’t thought about them for such a long time.” She also encouraged participants to use a memory retrieval technique (guided imagery) that is known to foster false memories. With these (and other) factors in play, Shaw and Porter persuaded many of their participants that just a few years earlier the participants had committed a crime that led to police contact. In fact, many participants seemed able to remember an episode in which they had assaulted another person with a weapon and had then been detained by the police. This felony never happened, but many participants “recalled” it anyhow. Their memories were in some cases vivid and rich with detail, and on many measures indistinguishable from memories known to be accurate.

Let’s be clear, though, that this study used many forms of influence and encouragement. It takes a lot to pull memory this far off track! There has also been debate over just how many of the participants in this study truly developed false memories. Even so, the results show that it’s possible for a large number of people to have memories that are emotionally powerful, deeply consequential, and utterly false. (For discussion of Shaw and Porter’s study, see Wade, Garry, & Pezdek, 2017. Also see Brewin & Andrews, 2017, and then in response, Becker-Blease & Freyd, 2017; Lindsay & Hyman, 2017: McNally, 2017: Nash, Wade, Garry, Loftus, & Ost, 2017; Otgaar, Merckelbach, Jelicic, & Smeets 2017: and Scoboria & Mazzoni, 2017.) Avoiding Memory Errors Evidence is clear that people do make mistakes-at times, large mistakes-in remembering the past. But people usually don’t make mistakes. In other words, you generally can trust your memory because more often than not your recollection is detailed, long-lasting, and correct. This mixed pattern, though, demands a question: Is there some way to figure out when you’ve made a memory mistake and when you haven’t? Is there a way to decide which memories you can rely on and which ones you can’t? Memory Confidence evaluating memories, people rely heavily on expressions of certainty or confidence. Specifically, people tend to trust memories that are expressed with confidence. (“I distinctly remember her yellow jacket; I’m sure of it.”) They’re more cautious about memories that are hesitant. (“I think she was wearing yellow, but I’m not certain.”) We can see these patterns when people are evaluating their own memories (e.g.. when deciding whether to take action or not, based on a bit of recollection); we see the same patterns when people are evaluating memories they hear from someone else (e.g., when juries are deciding whether they can rely on an eyewitness’s testimony). Evidence suggests, though, that a person’s degree of certainty is an uneven indicator of whether a memory is trustworthy. On the positive side, there are circumstances in which certainty and highly correlated (e.g., Wixted, Mickes, Clark, Gronlund, & Roediger, 2015; easily find exceptions to this pattern- forget that day; I remember it memory accuracy are we can Wixted & Wells, 2017). On the negative side, though, including memories that are expressed with total certainty (“I’ll never yesterday”) but that turn out to be entirely mistaken. In fact, we can find though it were as circumstances in which there’s no correspondence at all between how certain someone says she is, in recalling the past, and how accurate that recollection is likely to be. As a result, if we try to categorize memories as correct or incorrect based on someone’s confidence, we’ll often get it wrong. (For some of the evidence, see Busey, Tunnicliff, Loftus, & Loftus, 2000: Hirst et al., 2009: Neisser & Harsch, 1992; Reisberg, 2014; Wells & Quinlivan, 2009.) How can this be? One reason is that a person’s confidence in a memory is often influenced by factors that have no impact on memory accuracy. When these factors are present, confidence can shift (sometimes upward, sometimes downward) with no change in the accuracy level, with the result that any connection between confidence and accuracy can be strained or even shattered.

Participants in one study witnessed a (simulated) crime and later were asked if they could identify the culprit from a group of pictures. Some of the participants -“Good, you identified the suspect”; others weren’t. The feedback couldn’t possibly influence the were then given feedback accuracy of the identification, because the feedback arrived only after the identification had occurred. But the feedback did have a large impact on how confident participants said they’d been when making their lineup selection (see Figure 8.6), and so, with confidence inflated but accuracy unchanged, the linkage between confidence and accuracy was essentially eliminated. (Wells & Bradfield, 1998; also see Douglas, Neuschatz, Imrich, & Wilkinson, 2010; Semmler & Brewer, 2006; Wells, Olson, & Charman, 2002, 2003; Wright & Skagerberg, 2007.) Similarly, think about what happens if someone is asked to report on an event over and over. The repetitions don’t change the memory content-and so the accuracy of the report won’t change much from one repetition to the next. However, with each repetition, the recall becomes easier and more fluent, and this ease of recall seems to make people more confident that their memory is correct. So here, too, accuracy is unchanged but confidence is inflated-and thus there’s a gradual erosion, with each repetition, of the correspondence between accuracy and confidence. (For more disconnection between accuracy and confidence, see, e.g., Bradfield Douglas & Pavletic, 2012; Charman, Wells, & Joy, 2011.)

In many settings, therefore, we cannot count on confidence as a means of separating accurate memories from inaccurate ones. In addition, other findings tell us that memory errors can be just as emotional, just as vivid, as accurate memories (e.g., McNally et al., 2004). In fact, research overall suggests that there simply are no indicators that can reliably guide us in deciding which memories to trust and which ones not to trust. For now, it seems that memory errors, when they occur, may often be undetectable. e. Demonstration 8.2: Memory Accuracy and Confidence As you have seen, a large part of Chapter 8 is concerned with the errors people make when they’re trying to recall the past. But how powerful are the errors? Here is one way to find out. In this demonstration, you will read a series of sentences. Be warned: The sentences are designed to be tricky and are similar to one another. Several of the sentences describe one scene; several describe other scenes. To make this challenging, though, the scenes are interwoven (and so you might get a sentence about Scene 1, then a sentence about Scene 2, then another about Scene 1, then one about Scene 3, and so on).

Try to remember the sentences-including their wording-as accurately as you can. Try this so that you can really focus on the sentences. Can you avoid demonstration in a quiet setting, making any mistakes?

To help you just a little, the memory test will come immediately after the sentences, so that there’s no problem created by a long delay. To help you even more, the memory test will be a recoqnition test, so that the sentences will be supplied for you, with no demand that you come up with the sentences on your own. Finally, to allow you to do your best, the memory test won’t force you into a yes-or-no format. Instead, it will allow you to express degrees of certainty. Specifically, in the memory test you’ll judge, first, whether or not each test sentence was included in the original list. Second, you’ll indicate how confident you are, using 0 % to indicate “I’m really just guessing” and 100% to indicate “I’m totally certain.” Of course, you can use values between 0% and 100% to indicate intermediate levels of certainty.

In short, this is a demonstration designed to ask how good memory can be-with many factors in place to support performance: concrete, meaningful materials; ample warning about the nature of the materials; encouragement for you to give your best effort; immediate testing; recognition testing (not recall); and the option for you to “hedge your bets” by expressing your degree of certainty. Can we; in these ways, document nearly perfect memory?

Here are the sentences to memorize. Read them with care, because-as already mentioned- they are tricky to remember. HIDE

1. The girl broke the window on the porch.

2. The tree in the front yard shaded the man who was smoking his pipe.

3. The hill was steep.

4. The cat, running from the barking dog, jumped on the table.

5. The tree was tall.

6. The old car climbed the hill.

7. The cat running from the dog jumped on the table.

8. The girl who lives next door broke the window on the porch.

9. The car pulled the trailer.

10. The scared cat was running from the barking dog.

11. The girl lives next door.

12. The tree shaded the man who was smoking his pipe.

13. The scared cat jumped on the table.

14. The girl who lives next door broke the large window.

15. The man was smoking his pipe.

16. The old car climbed the steep hill.

17. The large window was on the porch.

18. The tall tree was in the front yard.

19. The car pulling the trailer climbed the steep hill.

20. The cat jumped on the table.

21. The tall tree in the front yard shaded the man.

22. The car pulling the trailer climbed the hill.

23. The dog was barking.

24. The window was large.

 

Now, close the list of sentences for the memory test.

 

Get a piece of paper and expand the list of sentences below. For each of the sentences, was the sentence on the previous list? If so, write “Old” Or is this a new sentence? If so, write “New.” Also, for each one, mark how confident you are, with 0% meaning “just guessing” and 100% indicating “totally certain.” Remember, you can also use values between 0% and 100% to indicate intermediate levels of certainty. SHOW Expand the first list of sentences. How well did you do? This is the moment at which we confess that there is a trick here: Every one of the test sentences was new. None of the test sentences were identical to the sentences used in the original presentation. For many of the test sentences, you probably (correctly) said “New” and were quite confident in your response. Which test sentences were these? Odds are good that you gave a high-confidence “New” response to a test sentence that mixed together elements from the different scenes. For example, you were probably confident and correct in rejecting “The old man who was smoking his pipe climbed the steep hill,” because the man with the pipe came from one scene (he was by the tree) and the steep hill came from a different scene (with the car climbing the hill). For these sentences, you could rely on your memory for the overall gist of the memory materials, and memory for gist tends to be quite good. On this basis, you easily (and accurately) rejected sentences that didn’t fit with that gist.

But for other test sentences, you probably said “Old” and may even have indicated 90% or 100% confidence that the sentences were familiar. But no matter how certain you were, you were wrong. nnot count on confidence as an indication of accurate memories. Let’s be clear, therefore, that we Even high-confidence recollection can be wrong.

As a separate implication, notice how hard it is to remember a sentence’s phrasing even in circumstances that are designed to help your memory. (Again, the testing was immediate. Recognition testing meant that you didn’t have to come up with sentences on your own. You were warned that the test would be difficult. You were trying to do well, and you’d been told that you should try to remember the sentence’s wording.) Even in this setting, errors (including high- confidence errors) can occur. Of course, one might argue that this is an acceptable pattern. After all, what you typically want to remember is the gist of a message, not the exact wording. Do you care whether you recall the exact phrasing of this paragraph? Or is it more important that you remember the point being made here? Nonetheless, there are situations in which you do want to remember the wording, and for that reason the results of this demonstration are troubling. There are also situations in which you might have misunderstood what you experienced, or your understanding might be incomplete. Those situations make it worrisome that what you remember seems to be dominated by your understanding, and not by the “raw materials” of your experience.

 

Demonstration adapted from Bransford, J. (1979). Human cognition: Learning, understanding and remembering, 1st ed. Belmont, CA: Wadsworth. 1979 Wadsworth, a part of Cengage Learning, Inc. Reproduced by permission (www.cengage.com/permissions). Forgetting We’ve been discussing the errors people sometimes make in recalling the past, but of course there’s another way your memory can let you down: Sometimes you forget. You try to recall what was on the shopping list, or the name of an acquaintance, or what happened last week, and you simply draw a blank. Why does this happen? Are there things you can do to diminish forgetting? The Causes of Forgetting Let’s start with one of the more prominent examples of “forgetting”-which turns out not to be forgetting at all. Imagine meeting someone at a party, being told his name, and moments later realizing you don’t have a clue what his name is-even though you just heard it. This common (and experience is not the result of ultra-rapid forgetting. Instead, it stems from a failure in acquisition. You were exposed to the name but barely paid attention to it and, as a result, never embarrass learned it in the first place.

What about “real” cases of forgetting-cases in which you once knew the information but no longer do? For these cases, one of the best predictors of forgetting (not surprisingly) is the passage of time. Psychologists use the term retention interval to refer to the amount of time that elapses between the initial learning and the subsequent retrieval; as this interval grows, you’re likely to forget more and more of the earlier event (see Figure 8.7). One explanation for pattern comes from the decay theory of forgetting, which proposes rather directly that memories fade or erode with the passage of time. Maybe this is because the relevant brain cells die off. Or maybe the connections among memories need to be constantly refreshed-and if they’re not refreshed, the connections gradually weaken.

 

A different possibility is that new learning somehow interferes with older learning. This view is referred to as interference theory. According to this view, the passage of time isn’t the direct cause of forgetting. Instead, the passage of time creates the opportunity for new learning, and it is the new learning that disrupts the older memories.

A third hypothesis blames retrieval failure. The idea here is that the “forgotten memory” is still in long-term storage, but the person trying to retrieve the memory simply cannot locate it. This proposal rests on the notion that retrieval from memory is far from guaranteed, and we argued in Chapter 7 that retrieval is more likely if your perspective at the time of retrieval matches the perspective in place at the time of learning. If we now assume that your perspective is likely to change as time goes by, we can make a prediction about forgetting: The greater the interval, the greater the likelihood that your perspective has changed, and therefore the greater the likelihood of retrieval failure. Which of these hypotheses is correct? It turns out that they all are. Memories do decay with the passage of time (e.g., Altmann & Schunn, 2012; Wixted, 2004; also Hardt, Nader, & Nadel, 2013; Sadeh, Ozubko, Winocur, & Moscovitch, 2016), so any theorizing about forgetting must include this factor. But there’s also no question that a great deal of “forgetting” is retrieval failure. This point is evident whenever you’re initially unable to remember some bit of information, but then, a while later, you do recall that information. Because the information was eventually retrieved, we know that it wasn’t “erased” from

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