Cognitive Psychology: Theory, Process, and Methodology - Dawn M. McBride, J. Cooper Cutting 2019

Memory Errors

Questions to Consider

· Does memory work like a video camera, fully recording each experience? Why or why not?

· In what ways does memory fail in normal individuals?

· What factors contribute to memory inaccuracies?

· How have researchers studied memory errors?

· How can different types of brain damage or deterioration affect memory accuracy?

Introduction: The Inaccuracy of Memory

On July 28, 1984, as Jennifer Thompson slept in her apartment, a man came into her room. The man raped her, but then Jennifer escaped. During the attack, Jennifer thought to herself that in case she survived, she needed to remember all the details of her attacker so that she could help catch and convict him. The police had Jennifer help a sketch artist draw a picture of her attacker. Then the police presented her with a photo lineup where pictures of several men were presented to her as possible suspects. Jennifer identified the photo of Ronald Cotton in the array shown to her as her attacker. Ronald was then brought in for a live lineup. Jennifer again identified him as her attacker. Based primarily on Jennifer’s identification of him, Ronald was convicted of the crime and sent to prison. Jennifer felt confident that she had helped put the right person in prison for her attack.

Ronald Cotton was actually innocent of the crime. While in prison, he learned that another inmate had confessed to raping Jennifer Thompson as well as other women. He attempted to have his verdict overturned. Eventually, DNA evidence from the crime was analyzed and it was clear that the inmate who confessed in prison was the man who attacked Jennifer. Ronald was exonerated and set free after eleven years in prison. When Jennifer saw the man who actually attacked her in the courtroom, she had no recognition of him at all, but Jennifer was consumed with guilt over sending the wrong person to prison. Jennifer’s case is only one of many where the wrong person was convicted based on eyewitness testimony. The Innocence Project reports that about 75 percent of cases that have been overturned with DNA evidence were for convictions based on eyewitness testimony.

Photo 7.1 Jennifer Thompson and Ronald Cotton

Photo 12/Alamy Stock Photo

How can our memories be so wrong? In a case where an accurate memory is so important and the person makes a concerted effort to encode the details of the event, the memory of the person who attacked her is still horribly wrong and has devastating consequences. This can occur even in cases where we are intentionally trying to remember something important, as in Jennifer’s case. One reason is that our memory does not provide a full and complete recording of our experiences, even in situations where an accurate memory is so important. It probably did not evolve for this purpose (see Nairne & Pandeirada, 2008). Instead, it likely developed to aid us in planning our future, making decisions, and having successful social interactions. Thus, it can be influenced by events that occur after an experience has been stored in our memory. For example, Jennifer’s memory of the person who attacked her was likely influenced by the police procedures (e.g., the lineups and the way they were conducted) and the subsequent conviction of a suspect. In addition, Ronald Cotton looked similar enough to the actual assailant so his description seemed to match the general sketch drawn up by the sketch artist before Ronald was arrested. This likely also gave Jennifer confidence in her identification of him in the lineup. Based on their experiences with the serious consequences that can result from such memory errors, Jennifer Thompson and Ronald Cotton, shown together in the photo that opens this chapter, now work together to advocate for changes in the way police conduct photo lineups. Nevertheless, having a memory that works by retrieving information through similarities and connections with our knowledge also has benefits in retrieving accurate memories. In this chapter, we explore the ways in which our memories can be inaccurate, both in normal individuals and in those who have had their memories damaged in some way, and why memory seems to be organized in this way.

The Seven “Sins” of Memory

When you think of people with poor memory abilities, you may think of older individuals who may have some memory deterioration or individuals who have suffered some form of brain damage. But as the opening story shows, even those with normal memory abilities can suffer from drastic memory errors. In his book The Seven Sins of Memory, Daniel Schacter (2002) described seven common memory failures that occur in individuals with normal memory abilities (see Figure 7.1). He describes these “sins” of memory as by-products of the way our memories function and typical of everyone to varying degrees. In fact, research on memory errors reviewed in this chapter shows that memory errors, such as the false memory of Ronald Cotton attacking her that Jennifer Thompson experienced, reveal the adaptive mechanisms by which memory operates and how we might design situations like eyewitness questioning to minimize such errors. These mechanisms also help our memories to be more accurate as they aid in retrieval of accurate memories. Later in this chapter, we also consider more atypical failures of memory in individuals with amnesia and types of dementia.

Figure 7.1 The Seven “Sins” of Memory Described by Daniel Schacter (2002)

SOURCE: Photo From BananaStock/BananaStock/ThinkStock.

Photo 7.2 Lineup procedures are important in preserving eyewitness’ memory accuracy.

©iStockphoto.com/RichLegg

Error #1 Transience

The first memory “sin” is transience. Transience is a term for normal forgetting of information over time. In Chapter 6, we described some possible causes of normal forgetting and the form this forgetting takes. Most information is forgotten very quickly after it is encoded, but over time less and less information is forgotten. In other words, the rate of forgetting of information is very high right after encoding, but the rate decreases as the time since encoding increases, such that forgetting slows down (see Figure 6.2). As described in Chapters 5 and 6, most memory researchers have rejected the idea of passive decay over time as the cause of forgetting. Instead, active processes of interference (from older or more recently encoded information) and consolidation (the strengthening of memories through neural cell processes) seem to most heavily influence forgetting. With more interference and less consolidation, more forgetting occurs. Results showing better memory when sleep occurs between encoding and retrieval support both of these descriptions of forgetting: Very little interference occurs while one is sleeping, and consolidation seems to work more effectively (perhaps because of the lack of interference) during sleep. Chapter 6 also describes some encoding methods that seem to result in better memory (i.e., less forgetting of information) such as processing the meaning of information and using imagery mnemonics.

Error #2 Absentmindedness

A lack of attention during encoding or retrieval results in poor memory (see Chapter 4 for further discussion of attention and its effects on cognition). Schacter (2002) terms this phenomenon absentmindedness. A good example of this memory failure is not remembering where you have placed something you need to find, such as your car keys. If you do not pay attention to their location when you put them down, there is a good chance you will not remember where they are (unless you always put them in the same place each time). Not remembering your intentions to perform tasks also falls under the memory failure of absentmindedness. Have you ever intended to go get something from another room in your house, but by the time you get to that room you have forgotten what you went there for because your attention has already wandered off to other thoughts? Remembering to complete a future task (e.g., taking medicine at a certain time, taking cookies out of the oven before they burn, calling your mom before you go to bed) is known as prospective memory (see Chapter 6 for more discussion of prospective memory). Failures of prospective memory are normal (Have you ever completed a homework assignment on time and then forgotten to turn it in?) and are described by Schacter as an absentmindedness “sin” of memory that we all fall prey to from time to time.

Photo 7.3 Not remembering where you left your keys illustrates the memory “sin” of absentmindedness.

©iStockphoto.com/peepo

Error #3 Blocking

Schacter (2002) describes blocking as an experience of knowing that you know information but being unable to retrieve it. This is also sometimes called a “tip-of-the-tongue” experience. (Chapter 9 also provides a description of this phenomenon with some other explanations of tip-of-the-tongue phenomena.) Most people have had this experience when they know the name of something (e.g., an actor, the name of a book or movie, a specific word they want to use in their writing) and may be able to remember what letter it starts with or what it sounds like but cannot retrieve the full name or word. This experience can be particularly anxiety provoking when you are blocking on someone’s name that you know you know and are in a situation where you need to introduce that person to someone else. This may have even happened to you during an exam: You know that you know the answer to the question, but you just cannot pull it out of your memory. I recently had this experience in trying to remember the name of the fifth Backyardigan character with my son (I forgot Austin). Another example I frequently encounter is that I can remember all but one of the movies nominated each year for the Academy Award for Best Picture. I can typically list all but one but seem to have trouble coming up with the last item on the list. Blocking seems to occur more frequently with proper names and unusual words because the terms are somewhat arbitrary in their assignment: There is no meaning connection to help us associate the name Heather with the person we just met to help us remember her name in the future.

Error #4 Source Misattribution

When we remember something as from a different source than the one it was actually learned from, we suffer from source misattribution. For example, there are likely times when you have a thought or idea about something that you think is an original thought you generated, but in reality you read or heard about the idea somewhere else first. This can also happen when you think one person told someone something (e.g., you think your biology professor said there might be a pop quiz in class next week), but later you realize it was someone else who said it (e.g., it was actually your psychology professor who said there might be a pop quiz next week). In this case, you thought the source of this memory was an actual experience of talking to someone, but the reality is that the memory’s source is just your own thought. Source misattribution may have played a role in Jennifer Thompson’s case. When she identified Ronald Cotton in the police lineup of live suspects, she may have been remembering him from the photo lineup she had already completed instead of from the attack she experienced. Other eyewitness cases have been found to be incorrect due to the “sin” of source misattribution. In these cases, eyewitnesses have erroneously identified someone as having committed the crime that they encountered in another (more innocent) situation.

Error #5 Suggestibility

Suggestibility likely also played a role in Ronald Cotton’s case. Jennifer reported that the police confirmed her choice of Cotton as the suspect when she picked him out of the lineup, giving her more confidence that Cotton was the man who attacked her, which likely altered her memory of the attack to fit him as the attacker. As we describe later in this chapter, others’ suggestions and statements can alter our memories for events in ways we do not even realize. This can be done both in altering actual memories and creating false memories for events we have never experienced. Have you ever had a clear memory of an event only to later find out that it was your brother, sister, or friend who actually experienced the event? Hearing about and imagining an event multiple times can create a memory for the event that seems real to us as something we experienced. President George W. Bush reported seeing video of the first plane hitting the World Trade Center in the U.S. terrorist attacks of September 11, 2001. However, no video of the first plane was ever found or shown in the media. Thus, it is likely that after hearing reports of the planes hitting the towers of the Trade Center and seeing the video repeatedly of the second plane hitting the building, he unknowingly created a false memory of the first plane that was suggested from these later experiences.

Error #6 Bias

Bias is a similar memory failure to suggestibility. Bias occurs when our current experiences or knowledge alter our memory of a past experience. For example, after going through an unpleasant breakup with a romantic partner, you may remember a happy event you experienced with that partner as more negative than it actually was. This can easily occur when our impressions of people change. Have you ever learned something unpleasant about a friend and then “remembered” that you found that person odd or unlikeable when you first met them? This might have occurred through bias, where your memory of meeting that person has been biased by your later discovery of that person’s true personality. Some women later remember the pain of childbirth as less painful than when they were experiencing it because they currently are experiencing happy times with their child. In other words, our current experiences and knowledge affect or bias the way we remember past experiences.

Error #7 Persistence

Persistence is a memory “sin” that can be particularly problematic for us. Do you sometimes hear a song and then later that day hear that song in your mind over and over? This is persistence: experiencing unwanted memories over and over. This particular situation can be annoying but can become more serious and debilitating if the unwanted memory is of a traumatic event. These types of memories are sometimes experienced by soldiers who were in combat and victims of violent crimes and can interfere with an individual’s daily life (see Photo 7.4). The re-experiencing of these memories can cause extreme anxiety and sleeplessness that becomes debilitating. In extreme cases, these memories are a primary symptom of post-traumatic stress disorder (PTSD) and can require psychological treatment to decrease them.

Photo 7.4 Experiencing unwanted memories repeatedly (such as memories of combat) illustrates the persistence “sin” of memory.

BPTU/Shutterstock

Summary

Each of the seven “sins” Schacter (2002) described is a by-product of memory failure or error that results from the normal mechanisms under which memory operates in our daily lives. In many cases, memory functioning seems so effortless to us that we do not notice these errors at all. However, when these errors or failures arise (e.g., not remembering an important concept during an exam), we realize the limitations of our memory abilities. While these memory failures can be irritating to us and in some cases have devastating results (as in Ronald Cotton’s case and in cases of PTSD), they are actually adaptive to us in our memory functioning. Having the ability to alter or block our memories (even in cases where we do not intentionally alter or block them) keeps us from being overwhelmed by memories we do not need and allows us to quickly retrieve the memories we need through their reconstruction. In fact, the reconstructive nature of memory is an important property of memory functioning that has implications for how we retrieve our memories (e.g., how best to question eyewitnesses) and when we can rely on them for accuracy.

Stop and Think

· 7.1. Which memory “sin” is the simple forgetting of information from memory?

· 7.2. Which memory “sins” involve changing an existing memory?

· 7.3. Can you think of an experience you have had that illustrates the “sin” of blocking? Of source misattribution?

The Reconstructive Nature of Memory

Memory researchers have long known that memory is reconstructive. We do not record and store all aspects of our experiences together. Instead, we encode and store the pieces of an experience (e.g., sights, sounds, scents) and then attempt to put the correct pieces back together when we retrieve our memory of the experience. At times, some of those pieces may be missing or replaced with incorrect pieces of other experiences or from our imaginations. This process occurs automatically, without our awareness, making us feel as if the memories we retrieve are accurate. The study of such errors has revealed the way this process works and what factors can influence this process. In this section, we discuss some of the important studies that have revealed the reconstructive nature of memory and how the reconstruction takes place.

Bartlett’s Studies

Sir Frederick C. Bartlett (1932) conducted studies on subjects’ abilities to reproduce simple stories, passages, and figures. Bartlett was interested in the accuracy of reproduction of the text or figures over time and the types of errors subjects made. After asking subjects to study the text or figures, Bartlett asked subjects to reproduce them after increasing intervals of time, beginning with a delay of about fifteen minutes. One of the main texts he used was a Native Canadian folk story that involved a fishing trip for two young men and a battle up the river (see Table 7.1 for the text of this story). As one would expect, he found that subjects could reproduce only some of the text word for word, but they seemed to have remembered many of the main points of the story for long periods of time. However, when subjects made errors in the story, they tended to be consistent with the subjects’ cultural biases (the subjects were students in the United Kingdom). For example, “canoes” in the story became “boats” in the reproductions, and “paddling” became “rowing.” These errors showed that the subjects relied on their own experiences and knowledge to fill in the details based on their general memory of the events, instead of remembering the details of these events. Bartlett’s studies were some of the first to show how memories of experiences are remembered based on the general meaning of the events they want to remember with details filled in (sometimes incorrectly) from subjects’ general knowledge.

Let us consider another classic study showing the importance of one’s perspective in reducing memory errors. Bransford and Johnson (1972) gave subjects the following passage to read and remember. Read through it and then see how much of it you can recall by covering it up and writing down what you remember:

The procedure is actually quite simple. First you arrange things into different groups depending on their makeup. Of course, one pile may be sufficient depending on how much there is to do. If you have to go somewhere else due to lack of facilities that is the next step, otherwise you are pretty well set. It is important not to overdo any particular endeavor. That is, it is better to do too few things at once than too many. In the short run this may not seem important, but complications from doing too many can easily arise. A mistake can be expensive as well. The manipulation of the appropriate mechanisms should be self-explanatory, and we need not dwell on it here. At first the whole procedure will seem complicated. Soon however, it will become just another facet of life. It is difficult to foresee any end to the necessity for this task in the immediate future, but one never can tell. (p. 722)

How well did you remember the passage? Most people cannot remember much of the passage. Bransford and Johnson’s subjects remembered about 15 percent to 23 percent (across three experiments) of the ideas in the passage when no topic was given to them. Other subjects were told ahead of time that the passage was about doing laundry, and these subjects remembered from 32 percent to 40 percent of the ideas (in three experiments), significantly improving recall scores. Simply knowing the topic ahead of time allowed the subjects to apply their own knowledge and experience to the passage while they read it and increased their ability to recall the passage accurately. When the topic was given to the subjects after reading the passage (as you were), no improvement in recall was seen. Thus, the effects of subjects’ prior knowledge seemed to occur while the passage was being read the first time in interpreting the different parts of it. The subjects’ knowledge that the passage was about doing laundry provided them with a schema for the information they were reading.

Schemata and Scripts

A schema is a general knowledge structure for an event or situation. For example, after visiting some of your professors’ offices, you may have a schema for what a professor’s office looks like: books on shelves, a desk, a computer, chairs, a telephone. If you were to visit one of your professor’s offices and then try to recall the objects in that office a couple of days later, you might recall objects that fit your schema of a professor’s office but were not actually in your professor’s office (see Photo 7.5). It seems we rely on our schemata to reconstruct memories of events and experiences that have familiar elements. In fact, Brewer and Treyens (1981) showed that our memory relies on our schemata in an experiment with a similar situation to the professor office visit just described. The subjects in their experiment were asked to wait in the experimenter’s office while the experimenter checked that the last subject had finished. After a short time, the subject was taken into another room and asked to describe the office he or she waited in. Subjects could accurately recall many of the objects from the office they waited in, and their schema for a university office likely contributed to that accurate recall, but they also falsely recalled objects that were not in the office. Many of the objects falsely recalled were consistent with a schema of a university office (e.g., books, a filing cabinet). Thus, the office schema may have helped subjects recall objects that were actually there, but it also resulted in recall of objects consistent with the schema that were not present in the office they waited in.

Schema: the general knowledge structure for an event or situation

Like schemata, scripts provide a general structure for a familiar event, but they involve an ordered set of actions that one holds in memory for that event. For example, you likely have a script for going out to eat at a restaurant. Think about the sequence of actions that takes place in this scenario. When you enter the restaurant, you approach a desk or podium to be greeted by the host or hostess, where he or she checks your reservation or sees if a table is available for you. The host or hostess then takes you to your table with menus if there is no wait for your table. Someone then comes to take drink orders while you read the menu. You can imagine the rest of the scenario and perhaps additional actions that might occur (e.g., a pager given to you if there is a wait for your table, going to the bar for a drink to wait for your table). You likely have additional scripts for other familiar situations. Do you have a script for doing laundry? If so, see how well your script matches the one presented in Figure 7.2. Consider why yours might deviate from the one in the figure. What differences might exist between your laundry experiences and those of the authors of this text that can account for the differences in the scripts? Also consider how well your script matches the earlier passage from the Bransford and Johnson (1972) study. Do the sentences make more sense in the context of your laundry script? Our own experiences alter the scripts and schemata we develop (as seen in the Bartlett studies), and the context in which we encounter information (e.g., with or without the topic information as in the Bransford and Johnson study) will alter how we encode the information, which then affects whether we can retrieve the information later.

Photo 7.5 In the Brewer and Treyens (1981) study, participants remembered items from a professor’s office that fit their schema for an office, but were not present in the office.

Stop and Think

· 7.4. What is meant by the “reconstructive nature of memory”?

· 7.5. In what way did Bartlett’s studies show that memory is reconstructive?

· 7.6. How do schemata and scripts aid in reconstructing memories?

· 7.7. Consider a script or schema you have that many others do not (e.g., how a certain sport is played, how things work at your job). In what ways do you think this script or schema influences your memories or specific experiences you have had in those situations?

Memory Errors in the Laboratory

As seen in the Bartlett studies, the study of memory errors can teach us much about the way memory typically works. Thus, memory researchers have conducted studies on how memory errors are created and ways to reduce the errors in situations where accurate memory is important (e.g., eyewitness memory). Some clever procedures have been devised for creating memory errors in order to examine the factors that increase or decrease them and better understand why they occur. We begin our discussion of these studies with a popular method of creating false memories (in this case, having a memory for something that did not happen) based on general schemata.

Figure 7.2 Script for Doing Laundry

Source: Photo ©iStockphoto.com/stphillips.

The DRM Procedure

In 1995, Roediger and McDermott published a study on false memories with a new methodology based on a much older study by Deese (1950). From the initials of these three authors, the method has become known as the DRM procedure and has been used in numerous studies in the past two decades to study the creation of false memories. An example of this method is presented in Figure 7.3. Look at each word in the list in the figure, going down the columns, for a few seconds each. Then cover the words up or turn the page and count backward from 167 for thirty seconds. At the end of thirty seconds, try to write down all the words in the list without looking back at the list. When you are finished recalling the words, check your responses.

DRM procedure (Deese-Roediger-McDermott procedure): research methodology that experimentally creates false memories for theme items that are not presented as part of a list of related items

Did you include any words not on the list? In particular, did you recall sleep, chair, king, or cold? If so, then your memory is like most people’s in that you created false memories for these items. Now, let’s consider why that might have happened. Look back at the list of words. Do you notice something about the words? In fact, the words all relate to one of four “themes” that correspond to sleep, chair, king, or cold. For example, the words in the “bed, rest, awake, tired” list all relate to the theme (or schema) of sleep. Seeing the words for the sleep schema (the first fifteen words in Figure 7.3) likely activated that schema (and the others just listed) for you during your study of the words. Then when you tried to recall the words in the list, your memory relied on the schema (perhaps even unconsciously) to try to recall the words, inserting errors based on the theme words.

Figure 7.3 An Example of Study Lists From the DRM Procedure

In their study, Roediger and McDermott (1995) had subjects study lists as you did in this example. The theme words were not presented in the lists. They then tested the subjects’ memory for the lists using both recall (i.e., write down all the words you remember in the list) and recognition (i.e., decide if each word shown was in the list and indicate your confidence in your response) tests. False memories for the theme words were high in both types of tests. Figure 7.4 illustrates their results for these tests. Recall and recognition rates for theme items not presented in the lists were high. Notice that the recall data show the serial position curve, with higher recall for items at the beginning (primacy effect) and the end (recency effect) of the list (see Chapter 6 for further discussion of the serial position curve). The number of false memories for theme words was similar to the recall rates of list items in the middle of the list where no primacy and recency effects occur. This makes sense because the theme words not in the lists cannot benefit from list position effects. The graph in Panel (b) of Figure 7.4 shows the response rates for items that subjects were sure were “old” (studied) and sure were “new” (not studied). Subjects were sure the theme items were “old” almost 60 percent of the time.

Figure 7.4 Results From Roediger and McDermott’s (1995) Experiment 1

Source: Adapted from Figure 1, Roediger, H. L., III, & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 803—814.

Numerous studies have employed the DRM procedure to study false memories for the theme items. These studies have found that false memories for the theme items show remarkable similarities to accurate memories for the list items that subjects have studied. For example, subjects will identify a source for the theme items (e.g., read in a male or female voice) as they do for the list items that were read to them (Payne, Elie, Blackwell, & Neuschatz, 1996). One study also found that a study-test delay affects list and false memories similarly when delays are relatively short (Colbert & McBride, 2007). Studies have even shown that electrophysical brain activity is similar for true recognition of list items and false recognition of theme items (Düzel et al., 1997; see Chapter 2 for details of this study).

Why does the presentation of themed lists in the DRM procedure produce such strong false memories for the nonpresented theme words? Researchers (e.g., Gallo, 2010; Roediger & McDermott, 1995) have suggested that two important memory processes are at play in the creation of false memories in the DRM procedure. The first process is activation of related items in memory. In Chapters 5 and 6, we discussed the idea that long-term memory organizes concepts by associations between the concepts (see Figure 5.1). When concepts (e.g., words) are presented, those concepts become activated in the network organization in long-term memory. When a concept or schema becomes activated, that activation then spreads to other related concepts in the network. (See Chapter 10 for further discussion of spreading activation in concepts.) Thus, when words like dream, night, bed, and blanket are presented, these concepts or schemata are activated in memory along with the related concept of sleep, even though sleep is not presented in the list. This spread of activation then causes sleep to seem similar to the actual list items in memory. When one attempts to remember the list items, the second process of source monitoring further works against accurate identification of list items. When we attempt to recall or recognize items, we consider whether a generated (in recall) or presented (in recognition) item was actually studied in the list. In other words, we try to determine the source (previously studied versus encountered somewhere else) of the item to decide if it was studied or not. When we source monitor for the theme items that were not presented, source misattribution (one of the “sins” of memory) can occur, allowing us to believe the item was studied along with the related list items. After all, it was activated in memory like the list items so it seems to us like a list item when we attempt to retrieve the list items. Additional activation of the theme items can also occur at test when the related list items are encountered (e.g., Coane & McBride, 2006), further confusing the two types of items in memory. Thus, both activation and source monitoring work together to produce false memories in the DRM procedure. Therefore, this theory is called the activation-monitoring theory of false memory creation.

A related theory of false memories, called fuzzy trace theory, suggests that when the themed lists are presented for study in the DRM procedure, a gist for the list is created and stored in memory. The gist matches the theme items closely because the lists were created to correspond to that theme item. When items are retrieved in a later memory test, the gist for the list is easily available (like the main ideas of the story in the Bartlett studies), whereas the details of the specific items have been lost (like the details of the story in the Bartlett studies). Thus, the theme items are falsely remembered as the gist for the list. This description of false memory creation is known as fuzzy trace theory (e.g., Brainerd & Reyna, 1998). Both the activation-monitoring and fuzzy trace theories have been supported by research studies and show some similarities in the way they describe false memories. In fact, they have been difficult to separate in tests of their predictions (Gallo, 2010).

In summary, the DRM procedure was an important step in helping us better understand memory errors because it allows researchers to easily and harmlessly create false memories in the laboratory so the factors that influence their creation can be studied. However, one drawback to this methodology is how different it may be from real-world creation of false memories. Some of the processes are likely to be similar in the DRM procedure and real-world false memories like the Ronald Cotton case (e.g., source misattribution), but critics of this method argue that studying a list of related words under controlled conditions is not similar enough to real-world situations such as experiencing or witnessing a crime. Other methods that better model real-world situations are needed to address this criticism. We next turn our discussion of false memories in the laboratory to these more realistic methods of study.

Stop and Think

· 7.8. How does the DRM procedure create false memories?

· 7.9. In what way are the false memories created by the DRM procedure “reconstructive”?

· 7.10. In what ways are the false memories created by the DRM procedure similar to accurate memories?

· 7.11. Consider a situation where it might be easy to make a source misattribution error in your life. Can you think of anything you can do to help you prevent this error?

Eyewitness Memory Studies

One of the most important real-world applications of knowledge about memory errors is in judging the accuracy of eyewitness memory. Numerous criminal investigations and legal cases rely on statements from eyewitnesses. The accuracy of their memory can strongly influence whether the correct person is arrested for a crime and whether that person is convicted of that crime. To better understand how accurate eyewitness memory really is, memory researchers (for example, Elizabeth Loftus, see Photo 7.6) have conducted studies that examined the effects of various factors on eyewitness memory. One factor that has emerged as important in altering the accuracy of an eyewitness’ memory is what the witness is exposed to after he or she witnesses the event, termed postevent information (Loftus, 2005). When the postevent information is incorrect or misleading, it can result in memory errors from the witness.

Photo 7.6 Elizabeth Loftus is a key researcher in eyewitness memory.

Don Tormey/Contributor/Los Angeles Times/Getty Images

Figure 7.5 Results From the Loftus and Palmer (1974) Study Showing the Misinformation Effect When Subjects Were Shown Videos of Car Accidents

Source: Photo © Can Stock Photo Inc./rjcphoto.

In a classic study examining the effects of postevent information that might be given in questions asked of eyewitnesses by investigators, Elizabeth Loftus and John Palmer (1974) asked subjects to watch videos of car accidents. After viewing the films, subjects were asked to recall what happened and then asked some questions about what they had seen. One key question asked subjects “How fast were the cars going when they _____ each other?” with the blank filled in with a specific verb that suggested a particular description of the crash. The researchers used the verbs smashed, collided, bumped, hit, and contacted for different groups of subjects. They found that the speed estimate subjects gave depended on the verb they were given in the question, with higher estimates of speed given for more violent verbs (e.g., smashed). Figure 7.5 illustrates the method and results of this study. In a second experiment, subjects viewed a car accident video and then received the speed estimate question with either smashed or hit as the verb. Again, higher speed estimates were given for smashed than for hit. A week later, the subjects returned and were asked again about the car accident in the video. This time they were asked if they saw any broken glass in the video, another suggestive question about the nature of the crash. A larger percentage of people said they saw glass if they had been asked the speed question with the verb smashed (32 percent) than if they had been asked with the verb hit (14 percent). No broken glass appeared in the video; these reports were false memories about the accident influenced by the type of question subjects were asked about the video they saw. Such results are known as the misinformation effect because subjects are misled by suggestive information given (in statements or questions) after they have witnessed an event. This information changes their memory of the event to create memory errors. The misinformation effect provides another example of the memory “sin” of suggestibility.

Misinformation effect: a memory result where subjects have false memories for an event based on suggestive information provided by others

Witnesses are also vulnerable to the misinformation effect when exposed to incorrect postevent information about an event, such as when they hear other witnesses’ inaccurate accounts of the event. For example, Stark, Okado, and Loftus (2010) simulated witnessing a crime by having subjects view photos of a man stealing a woman’s wallet. The next day the subjects heard a description of the crime that contained inaccurate information (e.g., the description suggested that the man put the wallet in his pants pocket when the photos showed him putting it in his jacket pocket). They then answered a series of questions about the event depicted in the photos. When subjects heard inaccurate information about the crime in the postevent description of the crime, they were more likely to answer questions about those details incorrectly. Thus, subjects had more false memories for details of the crime when they were exposed to inaccurate information after the crime, as might occur if they heard others’ inaccurate descriptions of the crime. Studies also suggest that memory errors due to misinformation are long lasting (e.g., more than a year; Zu et al., 2002) such that they can affect eyewitnesses for the length of a criminal case.

Some of the same processes that create false memories in the DRM procedure are suggested as mechanisms of memory errors in eyewitnesses. For example, hearing incorrect information about an event one experiences can “activate” those details about the event, with a source misattribution later causing one to think they are part of his or her memory of the event instead of from another source (e.g., another witness). Stephen Lindsay’s (1990) study showed that such source misattributions occur for postevent misinformation. In this study, subjects viewed slides of a crime where a man steals items from an office (see Photo 7.7). The slides were shown along with a verbal narrative of the events in the slides presented in a female voice. Subjects then heard a postevent description of the crime (different from the narrative presented with the slides) that contained some incorrect information about the slides, as was done in the Stark et al. (2010) study. However, half of the subjects heard the postevent description in the same female voice as the original slide narrative, making it difficult for the subjects to discriminate between the two descriptions. The other subjects heard the postevent description in a male voice, allowing them to distinguish the two descriptions better in their memories of the descriptions. Subjects then answered questions about the crime depicted in the slides. The results are shown in Figure 7.6, along with misremembered information that was not presented in the postevent description. Subjects who heard the male voice in the postevent description were less likely to be influenced by the incorrect information in the description than subjects who heard the postevent description in the same female voice as the original slide narrative. These results showed that subjects make source misattributions when they attempt to remember the details of the crime they witnessed in the slides.

Photo 7.7 In Lindsay’s (1990) study, slides of a crime were shown with a narrative in a female voice. A postevent description of the crime was then presented in the same female voice or in a male voice.

©iStockphoto.com/AndreyPopov

Applications of Eyewitness Memory Research

Given what we now know about eyewitness memory and the factors that influence its accuracy, what can we do to make eyewitness memory errors less likely? One thing we can do is change the way eyewitnesses are questioned, and police units around the world are making these changes to reduce the chance that inaccurate eyewitness testimony contributes to wrongful convictions. The changes focus on preventing suggestibility or leading information from the administrators of suspect lineups. The research conducted by cognitive psychologists showing misinformation effects from different types of postevent information has directly led to these specific reforms in police procedure (Wells et al., 1998).

Figure 7.6 Results From Lindsay’s (1990) Study Showing Source Misattributions

For example, many police departments in the United States now require a double-blind suspect lineup, where the person who administers the lineup to the witness does not know which person is the suspect to avoid the possibility of biasing the witness to choose the suspect or confirming his or her choice in the lineup as the suspect. This type of confirmation bias occurred in the lineup in the Jennifer Thompson case described at the beginning of the chapter (where a double-blind lineup was not used) and may have contributed to the wrongful conviction of Ronald Cotton. Research has shown that this confirming feedback can increase a witness’ confidence in his or her choice, even if that choice is incorrect (e.g., Wells & Bradfield, 1998). In addition, a warning is often given to witnesses that the suspect may not be present in the lineup. This reduces the chance that the witness will assume the person who committed the crime is in the lineup and will choose someone in the lineup even if he or she is not sure the person in the lineup is the correct person. This instruction gives someone the option of saying that the person he or she remembers is not present in the lineup. Suggestibility is also reduced when lineups are created with similar-looking individuals to avoid the suspect standing out as the only person who looks like who the witness remembers. Higher suggestibility may have also occurred in Jennifer Thompson’s case because Ronald Cotton looked like the actual perpetrator. Finally, research (e.g., Steblay, Dysart, Fulero, & Lindsay, 2001) has shown that showing possible suspects to the witness one at a time, instead of all at once, decreases false identifications in lineups. Such sequential lineup procedures are replacing the traditional simultaneous lineup procedures in many police departments. Thus, results from research in eyewitness memory are helping to reduce the problem of suspect misidentification.

Photo 7.8 Police departments are changing the way they question witnesses to reduce suggestibility errors in suspect identification.

Zak Kaczmarek/Stringer/Getty Images News/Getty Images

Research is also helping police departments find ways to question witnesses that prevent memory errors through postevent misinformation. The development of the cognitive interview (e.g., Geiselman, Fisher, MacKinnon, & Holland, 1986) has helped police question witnesses in a way that limits suggestibility and misleading information. The interview relies on four techniques designed to enhance retrieval of the details of an event (Memon, Meissner, & Fraser, 2010). The techniques come from basic principles of memory processing (some of which are discussed in Chapter 6 of this text). In the cognitive interview, the witness is asked to conduct a detailed retrieval of the event he or she experienced such that (1) the original context is reinstated in the witness’ mind (e.g., encoding specificity; see Chapter 6), (2) the witness reports everything he or she remembers even if it is incomplete to allow for retrieval of information a witness may have less confidence in, (3) the witness takes different perspectives of the event in his or her retrieval (e.g., other witnesses’ views), and (4) the witness retrieves events in different temporal orders (e.g., forward in time, backward in time).

Numerous studies have found that the cognitive interview increases accurate witness retrieval of event details compared with typical police questioning procedures. In fact, Memon et al. (2010) conducted a statistical review (called a meta-analysis) of sixty-five experiments involving the cognitive interview and showed that across these experiments, the cognitive interview increases retrieval of correct details of events with only a small increase in the number of incorrect details retrieved. Further, the Memon et al. study showed that the increase in correct details was highest for older adults, meaning that the cognitive interview may be particularly useful for older eyewitnesses, who are typically more influenced by misleading information (e.g., Cohen & Faulkner, 1989) and prone to source monitoring errors (e.g., Hashtroudi, Johnson, & Chrosniak, 1990). Based on the research showing positive effects of the cognitive interview, in 1999 the National Institute of Justice distributed training manuals for the cognitive interview to all U.S. police departments. Campo, Gregory, and Fisher (2012) conducted a field study to determine if South Florida police officers were using the technique described in these training manuals in their questioning of witnesses. Unfortunately, they found that the interviews sampled did not successfully use the cognitive interview techniques. Thus, there is room for improvement in translating the results of psychological science to real-world situations in this area.

Summary and Conclusions

Laboratory research in memory errors is providing us with a better understanding of how memory errors occur and ways they can be reduced in real-world situations. From the results of these studies, it is clear that memory errors result from normal underlying memory processes (e.g., familiarity of recently encoded information due to activation, source misattributions) and are therefore by-products of efficient memory mechanisms that do not “record” events in their entirety. Instead, our memories are reconstructive, relying on our schemata of events, prior knowledge, and our biases to put the pieces of a past event back together into a coherent whole. Understanding these processes has helped researchers better understand the limits of eyewitness memory accuracy and how we can avoid some of the errors in suspect identification and detail retrieval that can occur when witnesses are questioned or asked to view a suspect lineup. The results of these studies have aided in the development and implementation of improved police procedures to increase the accuracy of eyewitness memory.

Stop and Think

· 7.12. In what ways has research in eyewitness memory modeled real-world eyewitness situations?

· 7.13. Based on the results from research in eyewitness memory, what factors seem to increase memory errors in a witness?

· 7.14. What recommendations for questioning witnesses and conducting suspect lineups have come from the research in this area?

· 7.15. Consider an event you witnessed where it was later important for you to remember the details of the event (e.g., witnessing an accident or crime, experiencing an accident or crime). What factors occurred during or after the event that may have decreased your memory accuracy for the details of the event?

Although many of the errors presented in this chapter seem to have negative consequences, there may be a positive side to the creation of some kinds of errors. In a number of studies, Loftus and colleagues (e.g., Thomas & Loftus, 2002) have shown that imagining an event can create a false memory for that event. However, if one imagines a negative event related to something he or she wishes to avoid, the false memory can work to aid in avoiding that item or situation in the future. As an example of a positive application of false memory through imagining events, Clifasefi, Bernstein, Mantonakis, and Loftus (2013) reported that subjects who had false memories created by suggestions from researchers of an earlier event when they got sick drinking vodka showed a decreased preference for drinking vodka in the future. Thus, false memories might provide a useful way to avoid negative stimuli (like drinking too much alcohol) for individuals who wish to do so.

Clinical Memory Failures—Amnesia

Up to this point in the chapter, we have been discussing typical memory failures in a normally functioning memory system. We now turn our discussion to nontypical memory failures in clinical cases. Such failures take two forms: (1) a fairly immediate and discrete memory failure, such as in amnesic cases where a brain lesion has occurred due to an accident or disease or (2) a progressive deterioration of memory that becomes worse over time.

Types of Amnesia

Chapter 5 began with the story of Clive Wearing, who suffers from extreme amnesia. After suffering from a form of encephalitis, he was no longer able to remember events that he experienced and had forgotten many of the events of his past. Such cases are atypical, but they can occur when one suffers damage in particular brain areas due to a disease or accident. In Chapter 2, we presented another well-known case of amnesia in a man known as H. M., whose name was revealed as Henry Molaison after his death in 2008. H. M. suffered from epilepsy as a child that was severe enough to disrupt his daily life. When he was eighteen, surgery was performed in an attempt to reduce the frequency and severity of his seizures. Unfortunately, the surgery had an even more debilitating side effect: H. M. lost his ability to explicitly retrieve events that occurred after his surgery. During the surgery, the area known as the hippocampus (see Figure 7.7) in the medial temporal lobe (MTL) was damaged in H. M.’s brain along with surrounding areas of his MTL, which caused his anterograde amnesia (see Figure 7.8). In other words, H. M. seemed to remember who he was, his family, and his life up until the surgery but could not remember people he met or events he experienced after the surgery.

Amnesia: a memory deficit due to a brain lesion or deterioration

Hippocampus: an area of the brain important for memory encoding and retrieval

Figure 7.7 Cases Like H. M.’s Have Shown That the Hippocampus Is an Important Brain Area for Explicitly Retrieving Memories

Figure 7.8 Retrograde and Anterograde Amnesia

The other type of amnesia is retrograde amnesia (see Figure 7.8), which involves loss of memory for events that occurred before the brain damage. This might be the form of amnesia you first thought about when reading the title of the section, as it is the one commonly portrayed in movies and TV shows. This type of amnesia is most common after a head injury (e.g., due to the swelling of brain tissue) but is typically short-lived (i.e., many of the memories are eventually recovered) and limited to the events that occurred shortly before the damage. However, extreme cases of retrograde amnesia have been documented. For example, Doug Bruce, depicted in the documentary film Unknown White Male, describes suddenly becoming conscious one day on a New York train with no memory of who he was or where he was headed. This film depicts the various effects of retrograde amnesia on one’s life, most especially the social issues that come with not remembering your family and friends and having to rebuild those relationships. Doctors who examined Doug diagnosed him with a severe case of retrograde amnesia, but the cause was not clear despite several medical tests and examinations. Less is known about this type of amnesia because it is rare unless extensive damage to the hippocampus has occurred. Because the hippocampus works over time to store memories as long-term memories with consolidation (see Chapter 6 where the effects of sleep on memory are discussed), retrograde amnesia can occur for memories in the time preceding damage of this area. The hippocampus also seems to play a role in retrieving memories. For example, H. M. (see Photo 7.9) showed retrograde amnesia for events in the year or so preceding his surgery, and further testing of H. M. revealed that he could report very few details of most events in his life before the surgery (Lemonick, 2016). He could tell you that an event had occurred, but could not “relive” the event as many of us can for important occasions in our lives. It was as if H. M.’s episodic memories from before his hippocampus was damaged had become semantic memories, suggesting that the hippocampus may be important for retrieving memories as well as storing them.

Anterograde amnesia: a memory deficit for information or experiences encountered after a brain lesion

Retrograde amnesia: a memory deficit for information learned or experiences encountered before a brain lesion

Photo 7.9 Henry Molaison

Wikimedia Commons

Amnesia and Implicit Memory

Studies of amnesics such as H. M. have revealed important distinctions between types of memories and the brain areas responsible for these memories. In Chapter 5, we described the difference between implicit and explicit forms of memory. Much of our discussion in Chapters 5 to 7 has focused on explicit forms of memory involving intentional retrieval of a previous episode. This is the type of memory that is generally a problem for the types of amnesias described earlier. Implicit memory, however, involves unintentional retrieval of memory. In some cases, implicit memory is involved in a task without us being aware that our memory is being used at all. Amnesics like H. M. have shown the ability to use implicit memory, as measured by improvement on skills tasks performed over a series of days or weeks that they had no memory of having performed in the past (although his improvement was not as great as that shown by non-amnesic controls, Lemonick, 2016). The fact that individuals like H. M. show evidence of implicit memory is important because it suggests that amnesics most likely can encode some new memories; they just cannot explicitly retrieve them.

The use of implicit-memory tasks by researchers wanting to measure memories that are not intentionally retrieved increased significantly in the 1970s and 1980s. This increase was due in part to findings from two researchers in the United Kingdom showing that amnesics who have little to no memory for studied items in intentional-retrieval tests (e.g., recall, recognition) exhibit normal memory performance on implicit-memory tasks, like identifying word fragments (Warrington & Weiskrantz, 1968, 1970, 1974). Figure 7.9 illustrates the results from one of these studies comparing amnesics with normal control subjects. The amnesic subjects showed lower performance on the free-recall test than the normal control subjects (the small amount of memory they showed on this test is likely due to guessing guided by implicit memory) but showed similar performance to normal control subjects on the fragment-completion test. In other words, when they were intentionally retrieving studied items, the amnesic subjects performed poorly, but when they were simply asked to complete a related task without any reference to the studied items, the amnesic subjects showed performance indicating typical implicit memory. These results suggest that amnesics such as H. M. have not lost the ability to make new memories as was once believed. Instead, it seems that amnesics may have lost the ability to intentionally retrieve memories. Thus, amnesics seem to have deficits in explicit memory but do not typically show deficits in implicit memory.

Figure 7.9 Results From Warrington and Weiskrantz’s (1970) Experiment 1

Amnesia in Alzheimer’s Disease

Unlike the cases of amnesia just described that occurred somewhat suddenly after an injury, memory abilities can also deteriorate over time. One of the more common causes of progressive amnesia is Alzheimer’s disease. It is believed that Alzheimer’s disease occurs when neuron (i.e., brain cell) function is disrupted by plaques and tangles. Plaques are bundles of protein (generally beta amyloid protein) that develop in the space between neurons known as the synapse (see Chapter 2 for further discussion of neurons and their functions), disrupting communication between neurons. As the plaques spread throughout the brain, neuron communication deteriorates causing more severe dementia. Tangles are protein fibers (tau amyloid protein) that develop in a neuron’s nucleus, decreasing its ability to function properly. As more tangles spread throughout the neurons in the brain, less cognitive functioning occurs, resulting in dementia. See Figure 7.10 for a depiction of plaques and tangles in neurons. Neuron functioning is disrupted by both plaques and tangles in Alzheimer’s patients. Over time, massive cell loss drastically reduces brain mass (see Photo 7.10). Neuron function disruption seems to begin in the hippocampus in the early stages of Alzheimer’s disease (Gosche, Mortimer, Smith, Markesbery, & Snowdon, 2002). Because the hippocampus is important in explicit-memory retrieval (as already described), this is likely the cause of memory problems that signal the beginning of the disease symptoms.

Plaques: bundles of protein that develop in the synapse, characteristic of Alzheimer’s disease

Tangles: protein fibers that develop in a neuron’s nucleus characteristic of Alzheimer’s disease

Figure 7.10 Neuronal Plaques and Tangles in Alzheimer’s Patients

The incidence of Alzheimer’s disease is expected to rise with an increased aging population. Thus, prevention of the disease is a key research area in neuroscience. Current research suggests that both physical and cognitive activity can help reduce the incidence of the disease. For example, Erickson et al. (2011) showed that aerobic exercise increased the size of the hippocampus, which led to memory improvements in elderly subjects. Belleville et al. (2011) also showed that in individuals with mild cognitive impairment (often a precursor to Alzheimer’s disease), memory training with a cognitive task increased brain activity in areas related to memory on a later task. Better understanding of the link between brain function and these activities will aid efforts to reduce Alzheimer’s disease in the elderly.

Recent research has shown that the hippocampus is one of the first brain areas to be affected by the progression of Alzheimer’s disease (Mu & Gage, 2011). In fact, the hippocampus is one of the few brain areas where new neurons are formed throughout adulthood. However, with the onset of Alzheimer’s disease, the degradation of hippocampal neurons occurs faster than new neurons can form (Mu & Gage, 2011) and problems with memory begin to emerge due to the damage to neurons in this area. Further complicating matters, the hippocampus and the surrounding entorhinal cortex have been shown to be involved in learning of new procedural knowledge and relational processing (making meaningful connections between sets of information; Moser, Kropff, & Moser, 2008; O’Keefe & Nadel, 1978), which are important processes for learning new tasks. Future research into how to slow the destruction of neurons in the hippocampus and surrounding regions may eventually lead to treatments that can slow Alzheimer’s disease progression in individuals who are showing early symptoms.

Photo 7.10 Comparison of Alzheimer’s disease—damaged and normal brains

Science Source

Amnesia in Childhood

Amnesia (childhood or infantile amnesia) has also been used to describe the phenomenon of a lack of memory of one’s life before the age of five (the age range can vary by individual). However, amnesia in this case does not mean a complete absence of memories for this time period. Many people can remember a few episodes from before this age, especially if they have strong emotional content, but far fewer memories exist for this age range than for later in one’s life (Richmond & Nelson, 2007). Can you remember any episodes from your life from age two or three? My family moved to California when I was almost five; thus, I have many memories of growing up in Southern California but very few memories of living near Philadelphia where we lived before we moved. One suggestion for the cause of this lack of early childhood memories is that the areas of the brain (e.g., the hippocampus and the surrounding medial temporal lobe) responsible for very long-term storage of memories are not yet fully developed. The lack of a fully developed knowledge structure may also contribute to this phenomenon because, as we have discussed, connections to current knowledge are important for memory encoding. However, this does not mean that children of this age do not store information in long-term memory. My son can recite most of the dialogue from the Pixar Cars movies and remembered going on the Buzz ride at Disney World after we got home from our trip there when he was three years old, showing that he was storing information in long-term memory at this age. However, as he has gotten older, he has not retained many memories of that trip to Disney World, as memories from this age tend not to be stored over a longer time range. In addition, childhood amnesia seems to be specific to episodic memories. Semantic and implicit memories do not seem to show the same types of deficits in young children. My son knows that he went to Disney World when he was three years old (a semantic memory), but he does not remember meeting his great aunts on that trip (an episodic memory).

Childhood amnesia (infantile amnesia): a phenomenon where many episodic memories of early childhood are inaccessible in later life

Stop and Think

· 7.16. Describe the two types of amnesia based on the types of events that are forgotten.

· 7.17. Describe the two ways that amnesia can develop in individuals.

· 7.18. Are anterograde amnesics able to encode new memories? How do you know?

· 7.19. What is the proposed cause of amnesia in Alzheimer’s patients?

· 7.20. Imagine someone who is becoming elderly in your family has come to you for advice based on your knowledge of cognitive psychology on how to keep his or her memory abilities strong as he or she ages. What advice would you give this person?

Thinking About Research

As you read the following summary of a research study in psychology, think about the following questions:

1. Describe the memory errors the subjects in this study made. What is the likely cause of the errors?

2. In what way(s) is the method of this study similar to the DRM procedure described in this chapter?

3. What type of research design are the researchers using in this study? (Hint: Review the Research Methodologies section of Chapter 1 for help in answering questions 3 and 4.)

4. What is the independent variable in this study? What is the dependent variable in this study?

5. What do the results of this study suggest about the purpose of human memory?

Figure 7.11 Results From the Castel et al. (2007) Study Showing Benefits and Detriments of Expertise on Memory

Source: Castel et al. (2007, figure 1).

Study Reference

Castel, A. D., McCabe, D. P., Roediger, H. L., III, & Heitman, J. L. (2007). The dark side of expertise: Domain-specific memory errors. Psychological Science, 18, 3—5.

Purpose of the study: The researchers were interested in the effects of memory for expertise-related information. Subjects who were experts in American football and nonexpert subjects were tested for their memory of animal names, where each animal name was also the name of an American football team. They hypothesized that American football experts would remember more of the animal words than nonexperts but that they would also have more false memories for animal team name words that were not presented.

Method of the study: Subjects were 40 college students. They were asked to study two lists of 11 words in a random order. One of the study lists contained 11 animal names that were also names of American football teams (e.g., falcons, broncos, colts, jaguars). The other study list contained 11 body part names (e.g., toes, arm, stomach, neck) and was used as a control comparison list. Three items of each type (animal/team words and body parts) were not presented in the lists. These items served as possible false-memory items in the memory test. The words were shown for 1 second each. After both lists had been presented, subjects were asked to complete a filler task for 10 minutes. They were then asked to recall the words from each study list for 4 minutes. After the memory test, subjects completed a questionnaire to assess American football knowledge. Scores on this questionnaire were used to divide the subjects into expert and nonexpert groups of equal size.

Results of the study: For the animal/team words, expert subjects recalled more words than the nonexperts but also falsely recalled more words than the nonexperts. No differences were found between the expert and nonexpert groups for the body part words. Figure 7.11 shows the mean recall results for each word type and group of subjects.

Conclusions of the study: The results supported the researchers’ hypothesis that expertise affects both accurate and false memory for information in the area of expertise. These results illustrate both beneficial and detrimental effects of expertise on memory.

Chapter Review

Summary

· Does memory work like a video camera, fully recording each experience? Why or why not?

Research has shown that memory is reconstructive, putting the pieces of our memories back together when we retrieve them. The memory errors seen in individuals support this idea, rather than a “video camera” mechanism of memory.

· In what ways does memory fail in normal individuals?

Schacter (2002) described seven “sins” of memory as normal memory failures: transience (normal loss of information over time), absentmindedness (forgetting due to lack of attention), blocking (forgetting due to interference from other information), source misattribution (memory errors due to misattribution of the source of information), suggestibility (memory errors due to suggestions from outside sources), bias (memory errors due to our own experiences after the information was originally encoded), and persistence (unwanted memories of information that persist).

· What factors contribute to memory inaccuracies?

In general, normal memory processes can contribute to memory errors. For example, use of schemata, scripts, and our previous knowledge of events and concepts to reconstruct memories can result in errors. In cases of eyewitness memory, exposure to misleading information or inaccurate suggestions can result in memory errors.

· How have researchers studied memory errors?

The DRM procedure has been used to study how memory errors occur and what influences their creation. In this procedure, themed lists are presented and subjects typically show false memories for the themes that are not presented. Researchers have also studied memory for events by presenting subjects with a video or slides of an event, questioning them about the event or exposing them to other accounts of the event, and then testing their memory for the event they saw. These studies have helped us understand the factors that influence witness memory accuracy.

· How can different types of brain damage or deterioration affect memory accuracy?

Amnesia can occur due to brain injury or disease. It can happen suddenly, caused by an accident or illness, or progressively, as in Alzheimer’s disease. Both retrograde amnesia (loss of memory for events before the injury) or anterograde amnesia (loss of memory for events after the injury) can occur.

Chapter Quiz

1. Which memory “sin” is primarily due to a lack of attention at encoding or retrieval?

1. absentmindedness

2. persistence

3. suggestibility

4. blocking

2. Which memory “sin” results in unwanted memories?

1. source misattribution

2. persistence

3. suggestibility

4. bias

3. Which memory “sin” is synonymous with normal forgetting over time?

1. bias

2. persistence

3. suggestibility

4. transience

4. Which type of amnesia results in an inability to explicitly retrieve memories from after the brain damage has occurred?

1. semantic amnesia

2. anterograde amnesia

3. cortical amnesia

4. retrograde amnesia

5. Loftus’s studies of eyewitness memory showed that ______________ can alter the memory for an event.

1. a person’s schema

2. postevent information or suggestions

3. thematic activation

4. lack of confidence

6. A script is

1. the general meaning or gist of the information.

2. a cause of amnesia.

3. a stored set of actions typical of an event.

4. a network of stored concepts.

7. I have a memory that I took my medicine this morning, but in reality, I only thought about taking my medicine. This type of memory error represents the ________ “sin” of memory.

1. suggestibility

2. bias

3. transience

4. source misattribution

8. I arranged to call my friend at 3:00 p.m. when she had a break in her schedule. However, during the day, I was busy with many tasks and forgot to call at the scheduled time. This type of memory error represents the ________ “sin” of memory.

1. source misattribution

2. blocking

3. transience

4. absentmindedness

9. Explain why memory is described as reconstructive.

10. How do we know that amnesics like H. M. can store new memories?

11. Describe the two types of neuron function disruptions that occur in Alzheimer’s disease.

12. How has research in eyewitness memory changed police procedures in some departments?

13. Describe a situation where you (or someone you imagine) experienced the memory “sin” of bias.

Key Terms

· Amnesia 183

· Anterograde amnesia 184

· Childhood amnesia (infantile amnesia) 188

· DRM procedure (Deese-Roediger-McDermott procedure) 174

· Hippocampus 183

· Misinformation effect 179

· Plaques 186

· Retrograde amnesia 184

· Schema 173

· Tangles 186

Stop and Think Answers

· 7.1. Which memory “sin” is the simple forgetting of information from memory?

Transience

· 7.2. Which memory “sins” involve changing an existing memory?

Source misattribution, bias, and suggestibility all involve changing an existing memory.

· 7.3. Can you think of an experience you have had that illustrates the “sin” of blocking? Of source misattribution?

Answers will vary, but blocking involves lack of retrieval of information you know due to competing information you are retrieving at the same time. Source misattribution involves incorrectly attributing the source of information, such as thinking you said something when someone else did.

· 7.4. What is meant by the “reconstructive nature of memory”?

Memory is not a recording process. Instead, pieces of experiences are stored and then put back together in the retrieval process. Missing pieces can be filled in based on our general knowledge, biases, or postevent suggestions, creating memory errors.

· 7.5. In what way did Bartlett’s studies show that memory is reconstructive?

Subjects in these studies recalled the details of a story based on their own schemata for the events in the story. Their existing knowledge for these events changed their memories of the story as they attempted to retrieve it, showing that the story was reconstructed with pieces filled in from preexisting schemata.

· 7.6. How do schemata and scripts aid in reconstructing memories?

They help us fit information into our existing knowledge structure at encoding and fill in pieces of the memory for an event based on this existing knowledge structure at retrieval.

Answers will vary.

· 7.8. How does the DRM procedure create false memories?

Themed lists are presented without the theme items, and then false memories for the presentation of the theme items are created based on activation of the theme from the list items and source misattribution for the source of the activation at retrieval.

· 7.9. In what way are the false memories created by the DRM procedure “reconstructive”?

In retrieving the list items, one “reconstructs” the lists based on their meaning and the theme items are erroneously retrieved due to this reconstruction.

· 7.10. In what ways are the false memories created by the DRM procedure similar to accurate memories?

Subjects report confidence and recollective experiences (i.e., they claim to “remember” seeing or hearing the theme items in the list) for the theme items just as they do for list items. General memory process (e.g., forgetting and brain function) also seem to be similar for false and accurate memories in the DRM procedure.

· 7.11. Consider a situation where it might be easy to make a source misattribution error in your life. Can you think of anything you can do to help you prevent this error?

Answers will vary, but being aware of the possibility of errors and paying attention to the source of information can help reduce the errors.

· 7.12. In what ways has research in eyewitness memory modeled real-world witness situations?

This research has used a method where subjects are exposed to an event and then questioned about their memory for the event, just as eyewitnesses are in real-world situations. Postevent information is also sometimes used as it is in real-world situations.

· 7.13. Based on the results from research in eyewitness memory, what factors seem to increase memory errors in a witness?

Suggestive questioning and exposure to inaccurate or misleading information can lead to memory errors in these situations.

· 7.14. What recommendations for questioning witnesses and conducting suspect lineups have come from the research in this area?

Using neutral questioning (such as in the cognitive interview technique), presenting lineups with the possibility that no suspect is present, avoiding confirmations of lineup responses, and avoiding pop-out lineups where the suspect is the only one who looks like the perpetrator description are all recommendations that have come from research in this area.

Answers will vary, but bias and postevent information can be factors in this situation.

· 7.16. Describe the two types of amnesia based on the types of events that are forgotten.

In anterograde amnesia, memories formed after the brain damage occurred cannot be retrieved. In retrograde amnesia, memories formed before the brain damage occurred cannot be retrieved.

· 7.17. Describe the two ways that amnesia can develop in individuals.

Amnesia can occur suddenly, such as from an accident or illness, or progressively, such as in Alzheimer’s disease.

· 7.18. Are anterograde amnesics able to encode new memories? How do you know?

Anterograde amnesics can form new memories that can be retrieved implicitly. This has been shown with research using implicit-memory tasks, where retrieval is not explicit (i.e., intentional).

· 7.19. What is the proposed cause of amnesia in Alzheimer’s patients?

The proposed cause of Alzheimer’s disease is the formation of plaques and tangles in the brain that disrupt neuron function and communication.

Answers will vary, but research has shown that engaging in aerobic exercise and cognitive tasks can prevent the type of dementia seen in Alzheimer’s patients.

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