6.1 An Introduction to Memory

memory

The Conductor In 1985 conductor Clive Wearing (pictured here with his wife Deborah) developed a brain infection—viral encephalitis—that nearly took his life. Clive recovered physically, but his memory was never the same.

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Millions of people carry herpes simplex virus type 1 (HSV-1). Usually, it causes unsightly cold sores on the mouth and face. (There is also HSV-2, more commonly associated with genital herpes.) But for a small minority of the adult population—as few as 1 in 500,000 annually—the virus invades the central nervous system and causes a life-threatening infection called encephalitis. Left untreated, herpes encephalitis causes death in over 70% of its victims. Most who survive have lasting neurological deficits (Sabah, Mulcahy, & Zeman, 2012; Whitley & Gnann, 2002).

Although Deborah saw to it that Clive received early medical attention, having two doctors visit the house day and night for nearly a week, these physicians mistook his condition for the flu with meningitis-like symptoms (Wilson & Wearing, 1995). Misdiagnosis is common with herpes encephalitis (even to this day), as its symptoms resemble those of other conditions, including the flu, meningitis, a stroke, and epilepsy (Sabah et al., 2012). When Clive and Deborah arrived at the hospital on the 6th day of his illness, they waited another 11 hours just to get a proper diagnosis (Wearing, 2005; Wilson & Wearing, 1995).

Clive and Deborah, In Their Own Words

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Note: Quotations attributed to Dorothea Seitz are personal communications.

Clive survived, but the damage to his brain was extensive and profound; the virus had destroyed a substantial amount of neural tissue. And though Clive could still sing and play the keyboard (and spent much of the day doing so), he was unable to continue working as a conductor and music producer (D. Wearing, personal communication, June 18, 2013; Wilson & Wearing, 1995). In fact, he could barely get through day-to-day life. In the early stages of recovery, simple activities like eating baffled him. He ate the menu and attempted to spread cottage cheese on his bread, apparently mistaking it for butter. He confused basic concepts such as “scarf” and “umbrella,” and shaved his eyebrows and nose (Wearing, 2005; Wilson et al., 1995).

In the months following his illness, Clive was overcome with the feeling of just awakening. His senses were functioning properly, but every sight, sound, odor, taste, and feeling registered for just a moment, and then vanished. As Deborah described it, Clive saw the world anew with every blink of his eye (Wearing, 2005). The world must have seemed like a whirlwind of sensations, always changing, never stable. Desperate to make sense of everything, Clive would pose the same questions time and again: “How long have I been ill?” he would ask Deborah and the hospital staff members looking after him. “How long’s it been?” (Wearing, 2005, p. 181). For much of the first decade following his illness, Clive repeated the same few phrases almost continuously in his conversations with people. “I haven’t heard anything, seen anything, touched anything, smelled anything,” he would say. “It’s just like being dead” (Wearing, 2005, p. 160).

The Diary Looking at a page from Clive’s diary, you can see the fragmented nature of his thought process. He writes an entry, forgets it within seconds, and then returns to the page to start over, often writing the same thing. Encephalitis destroyed areas of Clive’s brain that are crucial for learning and memory, so he can no longer recall what is happening from moment to moment.

Jiri Rezac/Polaris/Newscom

The depth of Clive’s impairment is revealed in his diary, where he wrote essentially the same entries all day long. On August 25, 1985, he wrote, “I woke at 8:50 a.m. and baught [sic] a copy of The Observer,” which is then crossed out and followed by “I woke at 9:00 a.m. I had already bought a copy of The Observer.” The next line reads, “This (officially) confirms that I awoke at 9:05 a.m. this morning” (Wearing, 2005, p. 182). Having forgotten all previous entries, Clive reported throughout the day that he had just become conscious. His recollection of writing in his journal—along with every experience in his life—came and went in a flash. The herpes virus had ravaged his memory system.

The story of Clive Wearing launches our journey through memory. This chapter will take us to the opposite ends of a continuum: from memory loss to exceptional memory. We will travel to the World Memory Championships, an annual competition where memory competitors from around the globe gather to see how many numbers, words, and images they can squeeze into their brains in 3 days. You will learn some of their tricks, which might help you remember material for exams and everyday life: terms, concepts, passwords, pin numbers, people’s names, and where you left your keys. You, too, can develop superior memorization skills; you just have to practice using memory aids. But beware: No matter how well you exercise your memory “muscle,” it does not always perform perfectly. Like anything human, memory is imperfect.

An Overview of Memory

Memory refers to information the brain collects, stores, and may retrieve for later use. Much of this process has gone wrong or “haywire” for Clive. You may be wondering why we chose to start this chapter with the story of a person whose memory system failed. When it comes to understanding complex cognitive processes like memory, sometimes it helps to examine what happens when elements of the system are not working. Although we don’t completely understand how a functioning memory system works, there is basic agreement on the general processes involved; that is, how memories are encoded, stored, and retrieved.

Memory: Encoding, Storage, and Retrieval

What is your earliest memory and how was it created? Do you know if it is accurate? And how can you recall it after so many years? Psychologists have been asking questions like these since the 1800s. Exactly how the brain absorbs information from the outside world and files it for later use is still not completely clear, but scientists have proposed many theories and models to explain how the brain processes, or works on, data on their way to becoming memories. As you learn about the various theories and models presented here, keep in mind that none of them are perfect. Rather than labeling one as right and another as wrong, most psychologists embrace a combination of approaches, taking into consideration their various strengths and weaknesses.

One often used model likens the brain’s memory system to a computer. Think about how a computer operates: It receives data from external sources, like your fingers typing on the keyboard, and that data must be converted into a code the computer can manipulate. Once this is accomplished, the information can be saved on the hard drive so you can open up the documents, mp3s, and other data files you need. The brain‘s memory system accomplishes similar tasks, but as you will learn in this chapter, it is very different from a computer. Communication among neurons in the brain is more complicated than signals running between electrical components in a circuit. And unlike a computer, which maintains your files exactly how you last saved them, memories are subject to modifications over time, and this means they may be somewhat different each time you access them. Finally, the brain has seemingly unlimited storage capabilities, and the ability to process many types of information simultaneously, both consciously and unconsciously. Despite these differences, the computer serves as a useful metaphor to explain memory processes, including the encoding, storage, and retrieval of information.

During the course of a day, we are bombarded with external information coming from all of our senses and internal data from thoughts and emotions. Some of this information we will remember, but the majority of it will not be retained for very long. What is the difference between what is kept and what is not? Most psychologists agree that it all starts with encoding, the process through which information enters our memory system. Think about what happens when you pay attention to an event unfolding before you; stimuli associated with that event (sights, sounds, smells) are taken in by your senses and then converted to neural activity that travels to the brain. Once in the brain, the neural activity continues, at which point the information takes one of two paths: Either it enters our memory system (it is encoded to be stored for a longer period of time) or it slips away. For Clive Wearing, much of this information slips away.

The next step for information that is successfully encoded is storage. Storage is exactly what it sounds like: preserving information for possible recollection in the future. Before Clive Wearing fell ill, his memory was excellent. His brain was able to encode and store a variety of events and learned abilities. Following his bout with encephalitis, however, his ability for long-term storage of new memories was destroyed—he could no longer retain new information for more than seconds at a time.

After information is stored, how do we access it? Perhaps you still have a memory of your first-grade teacher’s face, but can you remember his/her name? This process of coming up with the name is called retrieval. Sometimes information is encoded and stored in memory, but it cannot be accessed, or retrieved. Have you ever felt that a person’s name or a certain vocabulary word was just sitting “on the tip of your tongue”? Chances are you were struggling from a retrieval failure, which we will discuss later in this chapter.

Before taking a closer look at the three processes of memory—encoding, storage, and retrieval—let‘s see what the memory system can do when it’s functioning at an optimal level. Welcome to the world of memory sport.

MEET THE MEMORY ATHLETES

The 18th Annual World Memory Championships had officially kicked off. Dorothea Seitz felt her heart pound as she flipped over her memorization sheet. The page was filled with row upon row of black-and-gray “abstract images” that any ordinary person would see as meaningless blobs, distinguishable only by subtle differences in shape, shade, and texture. But to Dorothea, these blobs were rabbits leaping off the page, fish splashing in water, or bizarre human faces—anything her mind could conjure up. Because one of the keys to memorization, most any memory champion will tell you, is a lively imagination. She had 15 minutes to memorize as many images as possible, a maximum of 330, in the order given.

Encephalitis The red area in this computerized axial tomography (CAT or CT) scan reveals inflammation in the temporal lobe. The cause of this swelling is herpes simplex virus, the same virus responsible for Clive’s illness. Many people carry this virus (it causes cold sores), but herpes encephalitis is extremely rare, affecting as few as 1 in 500,000 people annually (Sabah et al., 2012). Even with early treatment, this brain infection frequently leaves its victims with cognitive damage (Kennedy & Chaudhuri, 2002).

Airelle-Joubert/Science Source

Dorothea was the reigning junior champion, and she had come to defend her title. Sitting in that same London conference room with her were 73 other contestants from all over the world, including most of the hotshots in memory sport.

Silence saturated the room as contestants studied their memorization sheets. Many of them wore large ear plugs or earmuffs to cancel out any noises that might derail their train of thought—a sneeze, a pen hitting the floor, even the sound of someone breathing. Others wore dark glasses with tiny holes cut out of their centers, or side blinders like the kind racehorses wear—anything to keep their eyes from wandering from the task at hand.

When the 15 minutes was up, contest supervisors circulated the room collecting memorization sheets and distributing “recall sheets”—pieces of paper with the same images arranged in a different order. The contestants had only 30 minutes to unscramble them. Speeding through the recall phase of the event, Dorothea managed to remember 214 images. That put her in fourth place overall—not bad for a 17-year-old high school student competing against adults.

Dorothea had started the competition strong, but there were still nine events to go. The competitors would spend the next 3 days memorizing meaningless strings of numbers, random lists of words, imaginary historic dates, and other pieces of contrived “information.”

Memory Jocks Germany’s child memory champion Katharina Bunk studies a memorization sheet at a competition in Bad Wörishofen, Germany. In this “Names and Faces” event, the goal is to memorize as many name–face combinations as possible during the allotted time. Many competitors wear earmuffs and other devices to block out background noises that might interfere with their concentration.

Karl-Josef Hildenbrand/picturealliance/dpa/AP Images

The brains of memory champions are not wired in a special way; these are regular people who have trained themselves to excel in memory. Just ask eight-time World Memory Champion Dominic O’Brien if he thinks anyone can acquire an exceptional memory, and he will tell you there’s no doubt about it. When O’Brien first began to train his memory at age 30, he could remember no more than 6 or 7 playing cards in a row. Eventually, he was able to memorize 2,808 cards (54 decks) after looking at each card only once. “I transformed my memory power very quickly as a result of applying simple techniques and practicing regularly,” Dominic says. “If I can become a memory champion then anybody can” (D. O’Brien, personal communication, January 10, 2010). Just like a gymnast or a wrestler, a memory athlete prepares, trains, and practices. A powerful memory takes work!

2,808 Cards Memory master Dominic O’Brien took 54 decks of playing cards and memorized their correct order after flipping through them just once. By practicing memory techniques, Dominic went from being a person with an average memory to an eight-time World Memory Champion.

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One small study actually compared memory competitors to “normal” people and found nothing extraordinary about their intelligence or brain structure. What they did find was heightened activity in specific brain areas (particularly in regions used for spatial memory). This activity seemed to be associated with the use of a method for remembering items by associating them with an imagined “journey” (Maguire, Valentine, Wilding, & Kapur, 2003). As it turns out, memory champions like Dorothea and Dominic rely heavily on this type of imagined journey, which is rich with visual images. We will learn about this memory aid later in the chapter when we discuss memory improvement, but first we must get a grasp of how the entire system works. What exactly happens to data flowing into the memory system?

The Information-Processing Model of Memory

Psychologists employ several models that offer plausible explanations for how the memory system is organized. Among the most influential is the information-processing model, which suggests that memory operates in a series of stages (Figure 6.1). This model, first developed by Atkinson and Shiffrin, suggests that these stages represent a flow of information (Anderson, 1971; Atkinson & Shiffrin, 1968; Wood & Pennington, 1973).

FIGURE 6.1The Information-Processing Model of Memory

According to the information-processing model, the brain has three types of memory storage, each associated with a stage of memory: Sensory memorycan hold vast amounts of sensory stimuli for a sliver of time, short-term memory can temporarily maintain and process limited information for a longer stretch, and long-term memory has essentially unlimited capacity and stores enduring information about facts and experiences. In the upcoming pages, you will read much more about these stages of memory and how they relate to Clive Wearing, whose short- and long-term memory are severely impaired.

The information-processing model is a valuable tool for learning about and researching memory, but like any scientific model, it has flaws. Some critics contend that sensory memory is really a primary component of perception. Others doubt that a clear boundary exists between short-term and long-term memories (Baddeley, 1995). And still others argue that this “pipeline” model is a simplistic representation because information does not necessarily flow through the memory system in a straight-line path (Cowan, 1988). Despite its weaknesses, the information-processing model remains an essential tool for explaining how memory works.

Levels of Processing

Another way to conceptualize memory is from a processing standpoint. To what degree does information entering the memory system get worked on? According to the levels of processing framework, there is a “hierarchy of processing stages” that corresponds to different depths of information processing (Craik & Lockhart, 1972). Thus, processing can occur along a continuum from shallow to deep (Figure 6.2). Shallow-level processing is primarily concerned with physical features—characteristics like the brightness or shape of an object, for instance. Deeper-level processing relies on characteristics related to patterns and meaning, and generally results in longer-lasting and easier to retrieve memories. So when you pay only a little attention to data entering your sensory system, shallow processing occurs, resulting in more transient memories. If you really contemplate incoming information and relate it to memories you already have, deeper processing occurs, and the new memories are more likely to persist (Craik & Tulving, 1975; Francis & Gutiérrez, 2012; Newell & Andrews, 2004).

FIGURE 6.2The Levels of Processing Framework of MemoryInformation can be processed along a continuum from shallow to deep, affecting the probability of recall. Shallow processing, in which only certain details like the physical appearance of a word might be noticed, results in brief memories that may not be recalled later. We are better able to recall information we process at a deep level, thinking about meaning and tying it to memories we already have.

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Suppose you are trying to learn and remember the names of the three processes involved in memory: encoding, storage, and retrieval. You could try to memorize the words based on a shallow characteristic (storage has 7 letters, encoding has 8 letters, and retrieval has 9 letters), or you could think about the words on a deeper level, connecting them to concepts already stored in your memory system. Memory champion Dominic O’Brien came up with this one: Encoding makes him think of codes and secret agents, so he imagines a James Bond character going into a huge warehouse (storage facility) and seeing a golden retriever (retrieval) run out the door (D. O’Brien, personal communication, December 7, 2009). The more deeply you think about incoming information, considering its meaning or personal relevance, the greater success you will have learning and remembering it.

Fergus Craik and Endel Tulving explored levels of processing in their 1975 classic study. After presenting college students with various words, the researchers asked them yes or no questions, prompting them to think about and encode the words at three different levels: shallow, intermediate, and deep. The shallow questions required the students to study the appearance of the word: “Is the word in capital letters?” The intermediate-level questions related to the sound of the word: “Does the word rhyme with ‘weight’?” And finally, the deep questions challenged the students to consider the word’s meaning: “Is the word a type of fish?” When the researchers surprised the students with a test to see which words they remembered best, without any cues or clues, the students were best able to remember those words whose meaning they had thought about (Craik & Tulving, 1975). The take-home message: Deep thinking leads to firm memories (Foos & Goolkasian, 2008), particularly if you are trying to remember information with no cues for retrieval. Ask several people to do the following Try This and see if a deeper level of processing leads to better encoding and stronger memories, depending on which one of the three instructions you give them.

Most people have the greatest success with (3), but the impact of depth of processing depends somewhat on how you are prompted to retrieve information. For example, if someone asks you to remember any words that rhyme with “dive daring,” the name “Clive Wearing” will probably pop into your head regardless of whether you used deep processing.

Can you guess how deep thinking might help you succeed in school? Let’s find out how testing, which often requires you to connect new and old information, can improve your memory.

Who knew that testing actually could improve memory? Will this change your approach to studying for exams? A recent review strongly supports the finding that “testing improves learning,” as long as the stakes are low (Dunlosky, Rawson, Marsh, Nathan, & Willingham, 2013). The Show What You Know and Test Prep resources in this textbook are designed for just this purpose. Repeated testing, or the testing effect, results in a variety of benefits: better information retention; identification of areas needing more study; and increased self-motivated studying (Roediger, Putnam, & Smith, 2011; TABLE 6.1).

We have now introduced the information-processing model, which suggests that data travel through various memory stages: sensory, short-term, and long-term. We have also addressed the way in which levels of processing (shallow, intermediate, and deep) can influence our ability to retrieve information. In the next section, we will flesh out the concepts of sensory, short-term, and long-term memory, which are incorporated in most memory models. We will also examine a model that offers a more dynamic alternative to short-term memory.