Our Two-Track Memory System

As we have seen throughout this text, our mind operates on two tracks. This theme appears again in the way we process memories:

Our two-track mind, then, helps us encode, retain, and recall information through both automatic and effortful tracks. Let’s begin by seeing how automatic processing assists the formation of implicit memories.

Your implicit memories include automatic skills (such as how to ride a bike) and classically conditioned associations. If attacked by a dog in childhood, years later you may, without recalling the conditioned association, automatically tense up as a dog approaches.

Without conscious effort, you also automatically process information about

Your two-track mind processes information efficiently. As one track automatically tucks away routine details, the other track focuses on conscious, effortful processing. This division of labor illustrates the parallel processing we’ve also seen in Chapter 2 and Chapter 5. Mental feats such as thinking, vision, and memory may seem to be single abilities, but they are not. Rather, your brain assigns different subtasks to separate areas for simultaneous processing.

Automatic processing happens effortlessly. When you see words in your native language, you can’t help but register their meaning. Learning to read was not automatic. You at first worked hard to pick out letters and connect them to certain sounds. But with experience and practice, your reading became automatic. Imagine now learning to read sentences in reverse:

.citamotua emoceb nac gnissecorp luftroffE

At first, this requires effort, but with practice it becomes more automatic. We develop many skills in this way: driving, texting, and speaking a new language. With practice, these tasks become automatic.

Sensory Memory

Sensory memory (recall FIGURE 7.1) is the first stage in forming explicit memories. A memory-to-be enters by way of the senses, feeding very brief images of scenes, or echoes of sounds, into our working memory. But sensory memory, like a lightning flash, is fleeting. How fleeting? In one experiment, people viewed three rows of three letters each for only one-twentieth of a second (FIGURE 7.2). Then the nine letters disappeared. How many letters could people recall? Only about half of them.

Was it because they had too little time to see them? No—the researcher demonstrated that people actually had seen, and could recall, all the letters, but only briefly (Sperling, 1960). He sounded a tone immediately after flashing the nine letters. A high tone directed people to report the top row of letters; a medium tone, the middle row; a low tone, the bottom row. With these cues, they rarely missed a letter, showing that all nine were briefly available for recall.

This fleeting sensory memory of the flashed letters was an iconic memory. For a few tenths of a second, our eyes retain a picture-image memory of a scene. Then our visual field clears quickly, and new images replace old ones. We also have a fleeting sensory memory of sounds. It’s called echoic memory, because the sound echoes in our mind for 3 or 4 seconds.

Short-Term Memory Capacity

Recall that short-term memory refers to what we can briefly retain. The related idea of working memory also includes our active processing, as our brain makes sense of incoming information and links it with stored memories. What are the limits of what we can hold in this middle short-term stage?

Memory researcher George Miller (1956) proposed that we can store about seven bits of information (give or take two) in this middle stage. Miller’s Magical Number Seven is psychology’s contribution to the list of magical sevens—the seven wonders of the world, the seven seas, the seven deadly sins, the seven primary colors, the seven musical scale notes, the seven days of the week—seven magical sevens. After Miller’s 2012 death, his daughter recalled his best moment of golf: “He made the one and only hole-in-one of his life at the age of 77, on the seventh green . . . with a seven iron. He loved that” (quoted by Vitello, 2012).

Other researchers have confirmed that we can, if nothing distracts us, recall about seven digits, or about six letters or five words (Baddeley et al., 1975). How quickly do our short-term memories disappear? To find out how quickly, researchers asked people to remember groups of three consonants, such as CHJ (Peterson & Peterson, 1959). To prevent rehearsal, they distracted them (asking them, for example, to start at 100 and count backward by threes). Without active processing, people’s short-term memories of the consonants disappeared. After 3 seconds, they recalled the letters only about half the time. After 12 seconds, they seldom recalled them at all (FIGURE 7.3).

Working-memory capacity varies, depending on age and other factors. Compared with children and older adults, young adults have more working-memory capacity. Having a large working-memory capacity—the ability to juggle multiple items while processing information—tends to help them retain more information after sleep and to solve problems more creatively (De Dreu et al., 2012; Fenn & Hambrick, 2012; Wiley & Jarosz, 2012). Even so, whatever our age, our work is better and more efficient when we focus on one task at a time, without distractions. The bottom line: It’s probably a bad idea to try to watch TV, text your friends, and write a psychology paper all at the same time (Willingham, 2010)!

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Effortful Processing Strategies

Let’s recap. To form an explicit memory (a lasting memory of a fact or an experience) it helps to focus our attention and make a conscious effort to remember. But our working-memory desktop has limited space, and images, sounds, and other distractions compete for our attention.

We can boost our ability to form new explicit memories by using specific effortful processing strategies, such as chunking and mnemonics.

Memory whizzes understand the power of such systems. Star performers in the World Memory Championships do not usually have exceptional intelligence. Rather, they are superior at using mnemonic strategies (Maguire et al., 2003). Frustrated by his ordinary memory, science writer Joshua Foer wanted to see how much he could improve it. After a year of intense practice, he won the U.S. Memory Championship by memorizing a pack of 52 playing cards in under two minutes. How did Foer do it? He added vivid new details to memories of a familiar place—his childhood home. Each card, presented in any order, could then match up with the clear picture in his head. As the test subject of his own wild memory experiment, he learned that “you don’t have to be memorizing packs of playing cards to benefit from a little bit of insight into how your mind works” (Foer, 2011a,b).

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Effortful processing requires closer attention and effort, and chunking and mnemonics help us form meaningful and accessible memories. But memory researchers have also discovered other important influences on how we capture information and hold it in memory.

Spaced Study and Self-Assessment

We retain information better when our encoding is spread over time. Psychologists call this the spacing effect, and more than 300 experiments have confirmed that distributed practice produces better long-term recall (Cepeda et al., 2006). Massed practice (cramming) can produce speedy short-term learning and feelings of confidence. But to paraphrase pioneering memory researcher Hermann Ebbinghaus (1850–1909), those who learn quickly also forget quickly. You’ll retain material better if, rather than cramming, you space your study, with reviewing time later. How much later? If you need to remember something 10 days from now, practice it again tomorrow. If you need to remember something 6 months from now, practice it again a month from now (Cepeda et al., 2008). The spacing effect is one of psychology’s most reliable findings, and it extends to motor skills and online game performance (Stafford & Dewar, 2014). Memory researcher Henry Roediger (2013) sums it up: “Hundreds of studies have shown that distributed practice leads to more durable learning.” Distributing your learning over several months, rather than over a shorter term, can help you retain information for a lifetime.

One effective way to distribute practice is repeated self-testing, often called the testing effect (Roediger & Karpicke, 2006). Testing does more than assess learning; it improves it (Brown et al., 2014). In this text, for example, the Retrieve + Remember questions and Chapter Tests offer self-testing opportunities. Better to practice retrieval (as any exam will demand) than to merely reread material (which may lull you into a false sense of mastery). Happily, “retrieval practice (or testing) is [a] powerful and general strategy for learning” (Roediger, 2013). No wonder daily online quizzing improves introductory psychology students’ course performance (Pennebaker et al., 2013).

The point to remember: Spaced study and self-assessment beat cramming and rereading. Practice may not make perfect, but smart practice—occasional rehearsal with self-testing—makes for lasting memories.

Making New Information Meaningful

Spaced practice helps, but if new information is not meaningful or related to your experience, you will have trouble processing it. Imagine being asked to remember this passage (Bransford & Johnson, 1972):

The procedure is actually quite simple. First you arrange things into different groups. Of course, one pile may be sufficient depending on how much there is to do. . . . After the procedure is completed one arranges the materials into different groups again. Then they can be put into their appropriate places. Eventually they will be used once more and the whole cycle will then have to be repeated. However, that is part of life.

When some students heard the paragraph you just read, without a meaningful context, they remembered little of it. Others were told the paragraph described doing laundry (something meaningful to them). They remembered much more of it—as you probably could now after rereading it.

Can you repeat the sentence about the angry rioter (from this chapter’s opening section)?

Was the sentence “The angry rioter threw the rock through the window” or “The angry rioter threw the rock at the window”? If the first looks more correct, you—like the participants in the original study—may have recalled the meaning you encoded, not the words that were written (Brewer, 1977). In making such mistakes, our minds are like theater directors who, given a raw script, imagine a finished stage production (Bower & Morrow, 1990).

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We can avoid some encoding errors by translating what we see and hear into personally meaningful terms. From his experiments on himself, Hermann Ebbinghaus estimated that, compared with learning nonsense material, learning meaningful material required one-tenth the effort. As another memory researcher noted, “The time you spend thinking about material you are reading and relating it to previously stored material is about the most useful thing you can do in learning any new subject matter” (Wickelgren, 1977, p. 346).

The point to remember: You can profit from taking time to find personal meaning in what you are studying.