Psychology Themes and Variations (6th Canadian Edition) - PDF

CHAPTER 7 THEMES...

CHAPTER 7 THEMES IN THIS CHAPTER Theoretical Diversity Multifactorial Causation Subjectivity of Experience © Debbie Steel, Trent University Human Memory © Rebecca Atkins, York University Encoding: Getting Information into Memory 255 Storage: Maintaining Information in Memory 259 Retrieval: Getting Information Out of Memory 265 Forgetting: When Memory Lapses 268 In Search of the Memory Trace: The Physiology of Memory 276 Systems and Types of Memory 280 Putting It in Perspective: Themes 2, 4, and 7 284 PERSONAL APPLICATION Improving Everyday Memory 286 CRITICAL THINKING APPLICATION Understanding the Fallibility of Eyewitness Accounts 289 Concept Chart 291 253 02940_ch07_ptg01.indd 253 08/01/21 9:21 PM  H ave you ever thought about the possibility the present is clear. So, what does memory have to do of travelling through time? If you are like with time travel? most people, you have likely imagined Time travel itself, while clearly fascinating, isn’t how useful it might be in some situations. Time as rare as you might think; in fact, most of us can do travel would allow you to accomplish more—for it—and if you think carefully about it, it shouldn’t example, to take those extra classes that you are so surprise you to know that such time travel is inti- interested in, allowing you to complete your degree mately linked with the nature of our cognition and sooner than is ordinarily possible. The concept of memory systems (Ainslie, 2007; Cole & Kvavilashvili, time travel is fascinating and has been the subject 2019; Schacter & Addis, 2007a, 2007b). It is the of many books and movies. Can you remember nature of our cognitive and memory processes that any books you have read or movies you have seen allows us all to travel through time (Devitt & Addis, in the past couple of years in which time travel 2016; Michaelin, 2016; Miloyan et al., 2019; Schacter plays an important role? Of course, there are many et al., 2017; Tulving, 2005). We can go backward to well-known novels, including Charles Dickens’s remember specific events that happened to us, such A Christmas Carol (1843), H. G. Wells’s The Time as watching The Prisoner of Azkaban and the people Machine (1895), Robert Heinlein’s All You Zombies with whom we watched the movie. Other memories (1959), Kurt Vonnegut’s Slaughterhouse-Five (1969), are not tied to us personally but may relate more to Douglas Adams’s The Restaurant at the End of the general knowledge, such as what the word prisoner Universe (1980), Stephen King’s 11/22/63 (2011), means or what kind of animal a hippogriff is. Neal Stephenson and Nicole Gallant’s The Rise and These two kinds of memory—memory for general Fall of D.O.D.O. (2017), and Michael Crichton’s information and memory for personal events—were Timeline (1999). By the way, there was another labelled semantic and episodic memory, respectively, famous book published in 1999 that involved time by psychologist Endel Tulving (1972). Tulving’s well- travel. If you are like most others of your age (any known patient referred to as K.C. gives a dramatic age really, both of this textbook’s authors are fans), example of the distinction between these types of you have probably read the book or seen the movie memories (Rosenbaum et al., 2005). K.C. suffered of the same name that was released in 2004. Do you serious brain damage in 1981 after a motorcycle acci- remember the name of the book now? As a hint, dent. But you might never realize it if you restricted we can tell you that the author was J. K. Rowling. yourself to asking him questions such as “Who Harry Potter and the Prisoner of Azkaban is the answer. wrote The Time Machine?” After the accident, K.C.’s That was too easy! Let’s test your Harry Potter trivia semantic memory for facts was unimpaired. He was knowledge again. Do you remember the name of not distinguishable from anyone else and frequently the object that allowed Hermione to time travel? (If outperformed “normal” undergraduates at the not, you can find the answer at the end of this sec- University of Toronto, where Tulving conducted his tion). This might be more difficult—take a moment. work, on various cognitive/perceptual tasks. What If you can’t answer right away, it might seem that is impaired, however, is his episodic memory: No you almost know, that the answer is, well, on the tip matter how hard he tried, he could not remember of your tongue. Memory is a fascinating topic and anything that has ever happened to him (Tulving, process. While you are trying to remember, reflect 2001). He depended on a personal digital assistant a little on how you might describe to someone else to remind him to eat. K.C. admits that without the how you are able to remember such things or, per- device “I would get hungry but wouldn’t remember haps, why you cannot. These processes, including to eat. I wouldn’t know what time to go for lunch” remembering, forgetting, the tip-of-the-tongue phe- (Branswell & Hall, 2007, p. A6). nomenon, and much more, constitute the subject K.C. has been important in terms of our under- matter of this chapter on human memory. standing of memory (Rosenbaum et al., 2005). Our memory is something that helps define who Research with K.C. has contributed to, among other we are and our sense of self (Costabile & Austin, things, our knowledge about the distinction between 2020; Prebble et al., 2013), and it is intimately tied semantic and episodic memory, the distinction to our ability to function effectively and efficiently between implicit and explicit memory, and new in the immediate moment in both social (Anzellotti learning in amnesia (Kwan et al., 2012; Rosenbaum & Young, 2020; Hirst & Echterhoff, 2012) and non- et al., 2005; Rosenbaum et al., 2011). social contexts. In order to get to school on time, you In this chapter we focus on the nature of our have to remember where you left your room keys so memory systems. As the preceding discussion sug- you can lock the door before you leave. The impor- gests, memory involves more than taking informa- tance of memory in our ability to orient ourselves in tion in and storing it in some mental compartment. 254 CHAPTER 7 02940_ch07_ptg01.indd 254 08/01/21 9:21 PM  In fact, psychologists probing the workings of forget. Just as memory involves more than storage, memory have had to grapple with three enduring forgetting involves more than “losing” something questions: from the memory store. Forgetting may be due to deficiencies in any of the three key processes in 1. How does information get into memory? memory—encoding, storage, or retrieval. After our 2. How is information maintained in memory? discussion of forgetting, we will take a brief look at 3. How is information pulled back out of memory? the physiological bases of memory. Finally, we will These three questions correspond to the three key discuss the theoretical controversy about whether processes involved in memory: encoding (getting there are separate memory systems for different types information in), storage (maintaining it), and retrieval of information. The chapter’s Personal Application (getting it out). provides some practical advice on how to improve Encoding involves forming a memory code. For your memory. The Critical Thinking Application dis- example, when you form a memory code for a word, cusses some reasons why memory is less reliable than you might emphasize how it looks, how it sounds, or people assume it to be. what it means. Encoding usually requires attention. We began this introductory section discussing Storage involves maintaining encoded information the concept of time travel. It is of interest to psy- in memory over time. Psychologists have focused chologists not only because it seems to be tied up much of their memory research on trying to identify with our memory system, but also because it has just what factors help or hinder memory storage. been suggested that the ability to imagine oneself in Information storage isn’t enough to guarantee the future gives us an adaptive advantage in terms that you’ll remember something. You need to be able of our flexibility in dealing with novel situations to get information out of storage. Retrieval involves (Quoidbach et al., 2009; Suddendorf & Corballis, recovering information from memory stores. 2007). It has also been found that specific types Research issues concerned with retrieval include the of future mental time travel may help increase our study of how people search memory and why some happiness and reduce our stress (Quoidbach et al., retrieval strategies are more effective than others. 2009). Oh yes, we almost forgot: Hermione used a Most of this chapter is devoted to an examina- Time Turner in order to be able to attend more classes tion of memory encoding, storage, and retrieval. than she had time for. The use of the Time Turner also As you’ll see, these basic processes help explain the allowed for the rescue of Sirius Black and Buckbeak ultimate puzzle in the study of memory: why people (a hippogriff). Encoding: Getting Information into Memory Have you ever tried to remember an event or scene attention were distributed equally among all stim- that you had experienced (Zacks, 2020), or been ulus inputs, life would be utter chaos. You need to KEY LEARNING GOALS introduced to someone and then realized only 30 screen out most of the potential stimulation around Clarify the role of seconds into your interaction that you had already you in order to read a book, converse with a friend, attention and depth of forgotten their name? More often than not, this or even carry on a coherent train of thought. processing in memory. familiar kind of forgetting results from a failure to Attention is often likened to a filter that screens Explain how elabora- tion, visual imagery, form a memory code for the name. Active encoding out most potential stimuli while allowing a select few and motivation to is a crucial process in memory. In this section, we dis- to pass through into conscious awareness. However, remember can enrich cuss the role of attention in encoding, various types a great deal of debate has been devoted to where the encoding. of encoding, and the ways to enrich this process. filter is located in the information-processing system. The key issue in this debate is whether stimuli are The Role of Attention screened out early, during sensory input, or late, after You generally need to pay attention to information the brain has processed the meaning or significance if you intend to remember it (Lachter et al., 2004; of the input (see Figure 7.1). Mulligan, 1998). For example, if you sit through a Evidence on the “cocktail party phenomenon” class lecture but pay little attention to it, you’re suggests the latter. For example, imagine a young unlikely to remember much of what the professor woman named Tamara at a crowded party where had to say. Attention involves focusing awareness many conversations are taking place. Tamara is on a narrowed range of stimuli or events. Selective paying attention to her conversation with a friend attention is critical to everyday functioning. If your and filtering out the other conversations. However, Human Memory 255 02940_ch07_ptg01.indd 255 08/01/21 9:21 PM  Early-selection Late-selection memory performance are seen (Naveh-Benjamin models place models place et al., 2014). the filter here the filter here Although people tend to believe that they can multitask with no deterioration in performance (Dindar & Akbulut, 2016), research suggests that the Stimulus Sensory Recognition Response Response human brain can effectively handle only one atten- detection of meaning selection tion-consuming task at a time (Lien et al., 2006). When people multitask, they are really switching their attention back and forth among tasks, rather Recent evidence suggests that we may be able to move the than processing them simultaneously. That may be filter back and forth, placing fine in many circumstances, but the cost of divided it between these extremes attention does have profound implications for the Figure 7.1 Models of selective attention. Early-selection models propose that input is filtered before meaning advisability of driving while conversing on a cell- is processed. Late-selection models hold that filtering occurs after the processing of meaning. There is phone, for example. Carefully controlled research evidence to support early, late, and intermediate selection, suggesting that the location of the atten- clearly demonstrates that cellphone conversations tional filter may not be fixed. (Based on data from MacMillan et al., 1997) undermine people’s driving performance, even when Source: From Weiten, Psychology, 9e. Cengage Learning Inc. Reproduced by permission. www.cengage.com/permissions hands-free phones are used (Chen & Yan, 2013; Li et al., 2016; Strayer et al., 2006). if someone in another conversation mentions her Unfortunately, the distractions of cellphone con- name, Tamara may notice it, even though she has versations also reduce individuals’ appreciation of been ignoring that conversation. In experimental how poorly they are driving (Sanbonmatsu et al., simulations of this situation, about 35 percent of 2016). Many people rationalize their cellphone use participants report hearing their own name (Wood while driving by asserting that it enhances their & Cowan, 1995). If selection is early, how can these productivity, but research indicates that their multi- people register input they’ve been blocking out? This tasking undermines not only their driving, but cocktail party phenomenon suggests that attention also their recall of their auto-based conversations, involves late selection, based on the meaning of input. leading to memory errors that may actually decrease Which view is supported by the weight of sci- productivity (Watson et al., 2016). As distracting as entific evidence—early selection or late selection? cellphone conversations are, research indicates that Studies have found ample evidence for both as well texting while driving is even more dangerous (Caird as for intermediate selection (Cowan, 1988; Treisman et al., 2014; Rumschlag et al., 2015). 2009). These findings have led some theorists to con- There is some variability in how well people can clude that the location of the attention filter may be juggle multiple tasks. However, people generally flexible rather than fixed (Shiffrin, 1988). are not very accurate in predicting the degree to The importance of attention to memory is which multitasking will impair their performance apparent when participants are asked to focus (Calderwood et al., 2016). And those who report their attention on two or more inputs simultane- that they engage in more multitasking tend to be ously. Studies indicate that when participants are those who are least able to juggle multiple tasks forced to divide their attention between memory (Sanbonmatsu et al., 2013). As you might guess, encoding and some other task, large reductions in the data on multitasking and academic perfor- mance are not encouraging, as high levels of chronic multitasking have been linked to poor performance on classroom tests (Patterson, 2017), as well as stan- dardized achievement tests in math and English (Cain et al., 2016). Levels of Processing Solid photos/Shutterstock.com Attention is critical to the encoding of memories. But not all attention is created equal. You can attend to things in different ways, focusing on different aspects of the stimulus input. According to some the- orists, differences in how people attend to informa- tion are the main factors influencing how much they People think they can do several things simultaneously, but in reality they are switching their attention back and forth remember. Fergus Craik and Robert Lockhart (1972), among various tasks. both at the University of Toronto, proposed an 256 CHAPTER 7 02940_ch07_ptg01.indd 256 08/01/21 9:21 PM  important model in this area. In their formulation, Level of Type of Example of questions used to they argue that different rates of forgetting occur processing encoding elicit appropriate encoding because some methods of encoding create more Shallow Structural encoding: Is the word written in capital letters? durable memory codes than others (Craik, 2020). processing emphasizes the Craik and Lockhart propose that incoming infor- physical structure mation can be processed at different levels. For of the stimulus instance, they maintain that in dealing with verbal Depth of processing information, people engage in three progressively Intermediate Phonemic encoding: Does the word rhyme with weight? deeper levels of processing: structural, phonemic, and processing emphasizes what a semantic encoding (see Figure 7.2). Structural encoding word sounds like is relatively shallow processing that emphasizes the physical structure of the stimulus. For example, if Deep Semantic encoding: Would the word fit in the sentence: words are flashed on a screen, structural encoding processing emphasizes the “He met a _____________on the registers such matters as how they were printed (cap- meaning of verbal street”? ital letters, lowercase, and so on) or the length of the input words (how many letters). Further analysis may result in phonemic encoding, which emphasizes what a word Figure 7.2 Levels-of-processing theory. According to Craik (2002), Craik and Lockhart (1972), and Lockhart and sounds like. Phonemic encoding involves naming or Craik (1990), structural, phonemic, and semantic encoding—which can be elicited by questions such saying (perhaps silently) the words. Finally, semantic as those shown on the right—involve progressively deeper levels of processing, which should result in encoding emphasizes the meaning of verbal input; it more durable memories. involves thinking about the objects and actions the words represent. Levels-of-processing theory proposes that deeper levels of processing result in longer- memory codes. There are other dimensions to lasting memory codes. encoding, dimensions that can enrich the encoding In one experimental test of levels-of-processing process and thereby improve memory (Nairne et al., theory, Craik and Tulving (1975) compared the 2008): elaboration, visual imagery, and self-referent durability of structural, phonemic, and semantic coding. encoding. They directed participants’ attention to particular aspects of briefly presented stimulus words ELABORATION by asking them questions about various character- Semantic encoding can often be enhanced through istics of the words (see Figure 7.2). The questions a process called elaboration. Elaboration is linking were designed to engage the participants in different a stimulus to other information at the time of levels of processing. The key hypothesis was that encoding. For example, let’s say you read that pho- retention of the stimulus words would increase as bias are often caused by classical conditioning, and participants moved from structural to phonemic to you apply this idea to your own fear of spiders. In semantic encoding. After responding to 60 words, doing so, you are engaging in elaboration. The addi- the participants received an unexpected test of tional associations created by elaboration usually their memory for the words. As predicted, the par- help people to remember information. Differences ticipants’ recall was low after structural encoding, notably better after phonemic encoding, and highest after semantic encoding (see Figure 7.3). While the 100 Figure 7.3 theory is not without its critics, the hypothesis that Retention at three levels of deeper processing leads to enhanced memory has processing. In accordance been replicated in many studies (Baddeley & Hitch, 80 with levels-of-processing Words recognized (%) 2017; Craik, 2002; Lockhart & Craik, 1990). Levels- theory, Craik and Tulving of-processing theory has been enormously influen- 60 (1975) found that structural, phonemic, and semantic tial; it has shown that memory involves more than encoding, which involve pro- just storage and has inspired a great deal of research 40 gressively deeper levels of pro- on how processing considerations affect memory cessing, led to progressively better retention. (Data from (Arkes, 2016; Craik, 2020; Nunoi & Yoshikawa, 2016; Craik & Tulving, 1975). 20 Roediger et al., 2002). Enriching Encoding 0 Structural Phonemic Semantic Structural, phonemic, and semantic encoding do encoding encoding encoding not exhaust the options when it comes to forming Depth of processing Human Memory 257 02940_ch07_ptg01.indd 257 08/01/21 9:21 PM  in elaboration can help explain why different 12 approaches to semantic processing result in varied amounts of retention (Craik & Tulving, 1975). 10 VISUAL IMAGERY Average number of pairs recalled Imagery—the creation of visual images to represent 8 the words to be remembered—can also be used to enrich encoding. Of course, some words are easier to create images for than others. If you were asked 6 to remember the word juggler, you could readily form an image of someone juggling balls. However, 4 if you were asked to remember the word truth, you would probably have more difficulty forming a suit- able image. The difference is that juggler refers to a 2 concrete object, whereas truth refers to an abstract concept. Allan Paivio (1969, 2007) points out that it is easier to form images of concrete objects than of 0 High/ High/ Low/ Low/ abstract concepts. He believes that this ease of image high low high low formation affects memory. Imagery potential The beneficial effect of imagery on memory was Figure 7.4 demonstrated in a study by Paivio, Smythe, and Yuille The effect of visual imagery on retention. Participants given (1968). They asked participants to learn a list of 16 pairs of words to remember showed better recall for high-imagery pairs of words. They manipulated whether the words pairings than for low-imagery pairings, demonstrating that visual imagery can enrich encoding. (Data from Paivio, Smythe, & Yuille, were concrete, high-imagery words, or abstract, 1968) low-imagery words. In terms of imagery potential, the list contained four types of pairings: high– high (juggler–dress), high–low (letter–effort), low– and Kirker (1977). Like Craik and Tulving (1975), high (duty–hotel), and low–low (quality–necessity). these researchers manipulated encoding by asking Figure 7.4 shows the recall for each type of pairing. the participants certain kinds of questions. To induce The impact of imagery is quite evident. The best self-referent encoding, participants were asked recall was of high–high pairings, and the worst recall to decide whether adjectives flashed on a screen was of low–low pairings, showing that high-imagery applied to them personally. The results showed words are easier to remember than low-imagery that self-referent encoding led to improved recall words. Similar results were observed in another of the adjectives. Self-referent encoding appears to study that controlled for additional confounding enhance recall by promoting additional elaboration factors (Paivio et al., 2000). and better organization of information (Symons & According to Paivio (1986), imagery facili- Johnson, 1997). The implications of self-referent tates memory because it provides a second kind of encoding for understanding autism are explored in memory code, and two codes are better than one. His our first Featured Study. dual-coding theory holds that memory is enhanced by forming semantic and visual codes, since either can lead to recall. Although some aspects of dual- coding theory have been questioned, it’s clear that FEATURED STUDY the use of mental imagery can enhance memory in many situations (Marschark, 1992; McCauley et al., The self-reference effect in autism 1996). Description In this research, the authors examine whether the SELF-REFERENT ENCODING self-reference effect is shown by individuals with autism and its relevance for understanding some Making material personally relevant can also enrich aspects of memory processing in persons. encoding (Hamami et al., 2011). Self-referent Investigators encoding involves deciding how or whether infor- Lind, S. E., Williams, D. M., Nicholson, T., Grainger, C., & mation is personally relevant. This approach to Carruthers, P. (2020). Journal of Abnormal Psychology, encoding was compared to structural, phonemic, 129(2), 224–236. and semantic encoding in a study by Rogers, Kuiper, 258 CHAPTER 7 02940_ch07_ptg01.indd 258 08/01/21 9:21 PM  Storage: Maintaining Information in Memory In their efforts to understand memory storage, theo- Sensory Memory KEY LEARNING GOALS rists have historically related it to the technologies of The sensory memory preserves information in its their age (Roediger, 1980). One of the earliest models Describe the sensory original sensory form for a brief time, usually only used to explain memory storage was the wax tablet. store in memory, and a fraction of a second. Sensory memory allows the Both Aristotle and Plato compared memory to a discuss the durability sensation of a visual pattern, sound, or touch to linger and capacity of short- block of wax that differed in size and hardness for term memory. for a brief moment after the sensory stimulation is various individuals. Remembering, according to this Describe Baddeley’s over. In effect, people can react to the stimulus for a analogy, was like stamping an impression into the model of working brief period of time as if the stimulus was still present memory, and discuss wax. As long as the image remained in the wax, the (McBurney & Collings, 1984). In the case of vision, research on working memory would remain intact. memory capacity. people really perceive an afterimage rather than the Modern theories of memory reflect the techno- Evaluate the perma- actual stimulus. You can demonstrate the existence of logical advances of the 20th century. For example, nence of long-term afterimages for yourself by rapidly moving a lighted memory, and discuss many theories formulated at the dawn of the com- sparkler or flashlight in circles in the dark. If you move how knowledge is rep- puter age drew an analogy between information resented in memory. a sparkler fast enough, you should see a complete circle storage by computers and information storage in even though the light source is only a single point. human memory (Atkinson & Shiffrin, 1968, 1971; The sensory memory preserves the sensory image long Broadbent, 1958; Waugh & Norman, 1965). The enough for you to perceive a continuous circle rather main contribution of these information-processing than separate points of light. The memory is brief but theories was to subdivide memory into three separate can be extremely useful in reacting to changing situ- memory stores (Estes, 1999; Pashler & Carrier, 1996). ations. For visual information, this brief memory is The names for these stores and their exact charac- referred to as iconic memory. The parallel memory for teristics varied some from one theory to the next. acoustic information is referred to as echoic memory. For purposes of simplicity, we’ll organize our discus- In each case, the memory is a brief representation of a sion around the model devised by Richard Atkinson visual sensory or acoustic sensory stimulus. and Richard Shiffrin, which proved to be the most The brief preservation of sensations in sensory influential of the information-processing theories memory gives you additional time to try to recognize (e.g., Lehman & Malmberg, 2013). According to their stimuli. However, you’d better take advantage of sen- model, incoming information passes through two sory storage immediately because it doesn’t last long. temporary storage buffers—the sensory store and This fact was demonstrated in a classic experiment short-term store—before it is transferred into a long- by George Sperling (1960). The participants saw term store (see Figure 7.5). Like the wax tablet before three rows of letters flashed on a screen for just 1/20 it, the information-processing model of memory is a of a second. A tone following the exposure signalled metaphor; the three memory stores are not viewed as anatomical structures in the brain, but rather as functionally distinct types of memory. Sensory memory Short-term memory Long-term memory hearsal Re Storage Sensory input Attention Retrieval Wayne Weiten Figure 7.5 The Atkinson and Shiffrin model of memory storage. Atkinson and Shiffrin (1971) proposed that memory is made up of three information stores. Sensory memory can hold a large amount of information just long enough (a fraction of a second) for a small portion of it to be selected for longer Because the image of the sparkler persists briefly in sen- storage. Short-term memory has a limited capacity, and unless aided by rehearsal, its storage duration sory memory, when the sparkler is moved fast enough, the is brief. Long-term memory can store an apparently unlimited amount of information for indeterminate blending of afterimages causes people to see a continuous periods. stream of light instead of a succession of individual points. Human Memory 259 02940_ch07_ptg01.indd 259 08/01/21 9:21 PM  Figure 7.6 Fixation Display Tone Report Sperling’s (1960) study 1/20 second Tone occurs either of sensory memory. After before the display the participants had fixated goes off or at a delay on the cross, the letters were of 0.15, 0.30, 0.50, or flashed on the screen just long enough to create a visual 1 second afterimage. High, medium, G T F B High and low tones signalled Q Z C R Medium which row of letters to report. “G,T, F, B” Because participants had K P S N to rely on the afterimage to Low report the letters, Sperling was Pitch of tone able to measure how rapidly signals which row the afterimage disappeared to report by varying the delay between the display and the signal to report. Time (fractions of seconds) which row of letters the participant should report to DURABILITY OF STORAGE the experimenter (see Figure 7.6). Participants were Without rehearsal, information in short-term fairly accurate when the signal occurred immedi- memory is lost in less than 20 seconds (Nairne, 2003; ately. However, their accuracy steadily declined as Wickens, 1999). This rapid loss was demonstrated the delay of the tone increased to one second. Why? in a study by Peterson and Peterson (1959). They Because the memory trace in the visual sensory store measured how long undergraduates could remember decays in about 1/4 of a second. Memory traces in three consonants if they couldn’t rehearse them. To the auditory sensory store also appear to last less prevent rehearsal, the Petersons required the stu- than a second (Massaro & Loftus, 1996). While very dents to count backward by threes from the time brief, these sensory memories are clearly important the consonants were presented until they saw a light affecting, among other things, the richness of our that signalled the recall test (see Figure 7.7). Their visual perception, the accuracy of our construal of our results showed that participants’ recall accuracy was world, and the decisions we make (Vandenbrouke et pretty dismal (about 10 percent) after only 15 sec- al., 2014; Vlassova & Pearson, 2013). onds. Other approaches to the issue have suggested that the typical duration of STM storage may even be Short-Term Memory shorter (Baddeley, 1986). Short-term memory (STM) is a limited-capacity store that can maintain unrehearsed information for up CAPACITY OF STORAGE to about 20 seconds. In contrast, information stored Short-term memory is also limited in the number in long-term memory may last weeks, months, or of items it can hold. The small capacity of STM was years. However, there is a way that you can maintain pointed out by George Miller (1956) in a famous paper information in your short-term store indefinitely. called “The Magical Number Seven, Plus or Minus How? Primarily, by engaging in rehearsal—the pro- Two: Some Limits on Our Capacity for Processing cess of repetitively verbalizing or thinking about Information.” Miller noticed that people could recall the information. Cognitive psychologists often dis- only about seven items in tasks that required them to tinguish between maintenance rehearsal and more remember unfamiliar material. The common thread elaborative rehearsal or processing (e.g., Craik & in these tasks, Miller argued, was that they required Lockhart, 1972). In using maintenance rehearsal the use of STM. The limited capacity of STM con- you are simply maintaining the information in con- strains people’s ability to perform tasks in which they sciousness, whereas in more elaborative processing, need to mentally juggle various pieces of informa- you are increasing the probability that you will retain tion (Baddeley & Hitch, 1974). the information in the future (Brown & Craik, 2000) The capacity of short-term memory may even by, for example, focusing on the meaning of the be less than widely assumed. Nelson Cowan (2005, words in the list you are trying to remember. 2010) cites evidence indicating that the capacity of 260 CHAPTER 7 02940_ch07_ptg01.indd 260 08/01/21 9:21 PM  Warning Stimulus presentation Retention interval Recall signal and report Figure 7.7 Green signal 3 letters and a 3-digit Subject counts backward Red signal light: Peterson and Peterson’s light: trial about number by threes for intervals recall letters (1959) study of short-term to begin of 3 to 18 seconds memory. After a warning light was flashed, the participants were given three consonants to remember. The researchers 547… prevented rehearsal by giving 544… the participants a three-digit 541… number at the same time 538… and telling them to count. 535… “CJL 547”. “CJL ?” backward by three from that number until given the signal to recall the letters. By varying the amount of time between stimulus presentation and recall, Peterson and Peterson © Red Images, LLC/Alamy Stock Photo (1959) were able to measure how quickly information is lost from short-term memory. Time (seconds) letter separately because there are no obvious groups REALITY CHECK or chunks. But a string of 14 letters is too long for STM, so errors are likely. Now present the same string Misconception of letters to another person, but place the pauses in The capacity of short-term memory is seven plus or the following locations: minus two. ESPN - NETFLIX - IBM Reality Courtesy of George Miller Calling this assertion a misconception is a little harsh, The letters now form three familiar chunks that as it has been the conventional wisdom since the should occupy only three slots in STM, resulting in 1950s and there is room for argument on the matter. successful recall (Bower & Springston, 1970). However, in the last decade or so, researchers using To successfully chunk the letters N E T F L I X, more sophisticated methods have been chipping one must first recognize these letters as a familiar away at this maxim. The consensus among memory experts has shifted toward the belief that the capacity unit. This familiarity has to be stored somewhere in GEORGE MILLER of STM is four plus or minus one. long-term memory. In one recent study, participants’ “The Magical Number familiarity with various chunks—pairs of Chinese Seven, Plus or Minus Two.” characters—was manipulated to explore the effects STM might be even lower—four plus or minus one. of high versus low familiarity (Reder et al., 2016). The consensus on the capacity of STM seems to be Participants were asked to memorize associations moving toward this smaller estimate (Cowan, 2014, between pairs of Chinese characters (differing in 2015; Lustig et al., 2009). According to Cowan, the familiarity due to pretraining) and arbitrary English capacity of STM has historically been overestimated words and then took several weekly recall tests. because researchers have often failed to take steps to Participants exhibited better memory for associa- prevent covert rehearsal or chunking by participants. tions built on more familiar chunks. The researchers It has long been known that you can increase the conclude that familiar chunks consume less of the capacity of your short-term memory by combining limited capacity of STM than unfamiliar chunks. stimuli into larger, possibly higher-order units, called This finding is consistent with a new line of thought chunks (Simon, 1974). A chunk is a group of familiar asserting that the storage capacity of STM may be stimuli stored as a single unit. You can demonstrate somewhat flexible rather than fixed, depending on the effect of chunking by asking someone to recall a the familiarity and complexity of the stimuli (Brady sequence of 12 letters grouped in the following way: et al., 2016; Ma et al., 2014; Taylor et al., 2017). Individuals who are experts in specific areas have ES - PNNE - TFL - IXIB - M been shown to process and remember informa- As you read the letters aloud, pause at the hyphens. tion related to that expertise differently than non- Your subject will probably attempt to remember each experts (e.g., Guida & Campitelli, 2019). This was Human Memory 261 02940_ch07_ptg01.indd 261 08/01/21 9:21 PM  Figure 7.8 Working memory phone number. Baddeley (2003; Repovš & Baddeley, Short-term memory as r e h ea r s n ce 2006) believes that the phonological loop evolved working memory. This al i n t en a diagram depicts the revised to facilitate the acquisition of language. The second model of the short-term store component in working memory is a visuospatial Ma proposed by Alan Baddeley. sketchpad that permits people to temporarily hold According to Baddeley (2001), Phonological Central loop executive and manipulate visual images. This element is at working memory includes four components: a phonological work when you try to mentally rearrange the furni- rehearsal loop, a visuospatial ture in your bedroom or map out a complicated route sketchpad, a central executive that you need to follow to travel somewhere. system, and an episodic buffer. The third component is a central executive system. It controls the deployment of attention, switching the Visuospatial Episodic sketchpad buffer LTM focus of attention and dividing attention as needed (e.g., dividing your attention between a message you are trying to text to your friend during a lecture and what your professor told the class about next week’s exam, “What was that? Which chapters are on next week’s exam?”). The central executive also coordi- demonstrated by William Chase and the 1978 Nobel nates the actions of the other modules. The fourth Prize winner Herbert Simon, when they studied how component is the episodic buffer, a temporary, limited- expert and novice chess players remembered the capacity store that allows the various components positions of chess pieces on a chessboard after having of working memory to integrate information and a chance to look at the board for only a few seconds that serves as an interface between working memory (Chase & Simon, 1973). Chase and Simon (1973) sug- and long-term memory. The two key characteristics gested that the experts “chunked” the information that originally defined short-term memory—limited differently and more effectively. But this advantage capacity and storage duration—are still present in the holds only when the chess pieces appear in mean- concept of working memory, but Baddeley’s model ingful and familiar patterns. In this case, the expert’s accounts for evidence that STM handles a greater advantage lies in the ability to “encode the position variety of functions than previously thought. into larger perceptual chunks, each consisting of a Baddeley’s model of working memory has gen- familiar subconfiguration of pieces” (p. 80). erated an enormous volume of research (Courtney, 2004; Theeuwes et al., 2009). For example, one SHORT-TERM MEMORY AS line of research has shown that people vary in how “WORKING MEMORY” well they can juggle information in their working Research eventually suggested that short-term memory memory while fending off distractions (Engle, 2001). involves more than a simple rehearsal buffer, as origi- Working memory capacity (WMC) refers to one’s nally envisioned. To make sense of such findings, Alan ability to hold and manipulate information in Baddeley (1986, 1989, 1992) proposed a more complex, conscious attention. Working memory capacity is a modularized model of short-term memory that charac- stable personal trait (Unsworth, 2016) that appears terizes it as “working memory.” According to Baddeley to be influenced to a considerable degree by heredity (2003), working memory is a limited capacity storage (Kremen et al., 2007). That said, working memory system that temporarily maintains and stores infor- capacity can be temporarily reduced by situational mation by providing an interface between percep- factors, such as pressure to perform or rumination tion, memory, and action. Since its introduction, the (Curci et al., 2013; Moran, 2016). concept of “working memory” has proven invaluable Variations in working memory capacity correlate in our attempts to understand human behaviour and positively with measures of high-level cognitive experience (e.g., Baddeley, 2012; Bae & Flombaum, abilities, such as reading comprehension, com- 2013; Biderman et al., 2019; Camos, 2015; Rose et al., plex reasoning, and even intelligence (Logie, 2011; 2012; Sims et al., 2012). While the term was first used Chuderski, 2015). This finding has led some theorists by Miller, Galanter, and Pribaum (1960), it is Baddeley’s to conclude that working memory capacity is critical model that has been most influential. to complex cognition (Lepine et al., 2005). Baddeley’s model of working memory consists of four components (see Figure 7.8). The first compo- Long-Term Memory nent is the phonological loop that represented all of Long-term memory (LTM) is an unlimited capacity STM in earlier models. This component is at work store that can hold information over lengthy when you use recitation to temporarily remember a periods of time. Unlike sensory and short-term 262 CHAPTER 7 02940_ch07_ptg01.indd 262 08/01/21 9:21 PM  memory, which have very brief storage durations, York City and Washington, DC; or the first death in LTM can store information indefinitely. In fact, one their community related to the COVID-19 pandemic point of view is that all information stored in long- in 2020 (Government of Canada, 2020a). Although term memory is stored there permanently. According flashbulb memories have mostly been studied in rela- to this view, forgetting occurs only because people tion to negative events, people also report flashbulb sometimes cannot retrieve needed information from memories of positive events (Kraha & Boals, 2014). LTM. For example, Tinti and colleagues (2014) studied The notion that LTM storage may be permanent is flashbulb memories in Italian citizens after Italy won certainly intriguing. A couple of interesting lines of the World Cup in 2006. research have seemed to provide compelling evidence Does the evidence on flashbulb memories provide of permanent storage. However, each line of research adequate support for the idea that long-term memory turns out to be less compelling than it appears at first storage is permanent? No, research eventually showed glance. The first line of research consisted of some that flashbulb memories are perhaps neither as accu- landmark studies conducted by neuroscientist Wilder rate nor as special as once believed (Hirst & Phelps, Penfield at McGill University. He reported triggering 2016; Hirst et al., 2009; Schmolck et al., 2000). Like long-lost memories through electrical stimulation other memories, they become less detailed and com- of the brain (ESB) during brain surgeries (Penfield & plete with time and are often inaccurate (Talarico & Perot, 1963). When Penfield used ESB to map brain Rubin, 2009). That said, a ten-year follow-up on indi- function in patients undergoing surgery for epilepsy, viduals’ flashbulb memories for their learning about he found that stimulation of the temporal lobe some- the 9/11 attacks found little erosion of memory after times elicited vivid descriptions of events long past. the first three years (Hirst et al., 2015). Still, the data Patients would describe events that apparently came yielded estimates that people’s flashbulb memories from their childhood—such as “being in a lumber- were only about 60 percent accurate. Research sug- yard” or “watching Mom make a phone call”—as gests that it is not extraordinary accuracy or lon- if they were there once again. Penfield and others gevity that distinguish flashbulb memories. Rather, inferred that these descriptions were exact playbacks what makes them special is that people subjectively of long-lost memories unearthed by electrical stimu- feel that these memories are so exceptionally vivid lation of the brain. that they have exceptional confidence (albeit mis- The existence of flashbulb memories is one piece of placed) in their memories’ accuracy, and that more evidence that has been cited to support the notion emotional intensity is attached to these recollections that long-term memory storage may be perma- (Hirst & Phelps, 2016; Talarico & Rubin, 2003, 2007). nent. At first glance, flashbulb memories, which are We know that factors such as emotion can dramati- thought to be unusually vivid and detailed recollec- cally facilitate memory (Kensinger & Ford, 2020). So, tions of momentous events, provide striking exam- perhaps flashbulb memories are “special” but not in ples of seemingly permanent storage (Brown & Kulik, the way originally envisioned. 1977). Many adults, for instance, can remember Returning to the question at hand, the research exactly where they were, what they were doing, findings on flashbulb memories conflict with the Dan Howell/Shutterstock.com and how they felt when they learned of the death hypothesis that memory storage is permanent. of a favourite celebrity such as musicians Prince or Although the possibility cannot be ruled out com- David Bowie, both in 2016; or traumatic events such pletely, there is still no convincing evidence that as the 2001 terrorist attacks that took place in New memories are stored away permanently and that Flashbulb memories are CONCEPT CHECK 7.1 vivid and detailed recol- lections of momentous Comparing the Memory Stores events. For example, many people will long remember Check your understanding of the three memory stores by filling in the blanks in the table below. The answers can be exactly where they were found near the back of the book in Appendix A. and how they felt when they learned about the ter- Sensory Short-term Long-term rorist attacks on the World Feature memory memory memory Trade Center. Main encoding format copy of input Largely semantic Storage capacity Limited Storage duration up to 20 seconds Human Memory 263 02940_ch07_ptg01.indd 263 08/01/21 9:21 PM  Level memory storage: How is knowledge represented 1 Minerals and organized in memory? In other words, what forms do our mental representations of information take? Most theorists seem to agree that our mental 2 Metals Stones representations probably take a variety of forms, depending on the nature of the material that needs to be tucked away in memory. Most of the theorizing 3 Rare Common Alloys Precious Masonry to date has focused on how factual information may be represented in memory. In this section, we’ll look 4 Platinum Aluminum Bronze Sapphire Limestone at a small sample of the organizational structures Silver Copper Steel Emerald Granite Gold Lead Brass Diamond Marble that have been proposed for semantic information. Iron Ruby Slate CATEGORIES AND CONCEPTUAL Figure 7.9 HIERARCHIES Conceptual hierarchies and long-term memory. Some types of information can be organized into a multilevel hierarchy of concepts, like the one shown here, which was studied by Bower and others People spontaneously organize information into (1969). They found that participants remember more information when they organize it into a concep- categories for storage in memory. This reality was tual hierarchy. apparent in a study by Bousfield (1953), who asked Source: Reprinted from Cognitive Psychology, 1(1), Gordon H. Bower, Organizational factors in memory, pp. 18–46. Copyright © 1970, with permission from Elsevier. participants to memorize a list of 60 words. Although presented in a scrambled order, each of the words forgetting is all a matter of retrieval failure (Payne & in the list fits into one of four categories: animals, Blackwell, 1998; Schacter, 1996). men’s names, vegetables, or professions. Bousfield showed that participants recalling this list engage How Is Knowledge Represented and in clustering—the tendency to remember similar or Organized in Memory? related items in groups. Even though the words were Over the years, memory researchers have wrestled not presented in organized groups, participants tended endlessly with another major question relating to to remember them in bunches that belonged in the