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work was really hers. Another strategy is to connect the source with the information
always, even if you are putting that source’s information into your own words. An
explanation for an idea can be interpreted in many ways, but the idea itself—no
matter how it is phrased—still has to be connected to its originator. Abramson also
admitted to not giving credit to the proper sources when she rephrased their original
ideas (Malooley, 2019). She gave Malooley a personal apology, but the damage had
already been done. So, if a highly skilled writer can use these simple strategies to
avoid plagiarism, you can too.
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LEARNING CHECK
Partial Recall
It’s harder to recall information without external cues than it is to select a
remembered item from a list of alternatives. Bear that in mind as you ponder these
questions about long-term memory.
(Answers: 1. free recall; 2. b; 3. context-dependent; 4. c; 5. elaborative
rehearsal.)
Forgetting
Before we celebrate the virtues of memory and outline the techniques we can use
to improve it, let’s stop and ponder the wisdom of William James (1890), who said, “If
we remembered everything, we should on most occasions be as ill off as if we
remembered nothing” (p. 680). James was right. Many years ago, Russian
psychologist Alexander Luria (1968) described his observations of Solomon
Shereshevskii, a man he called S., who had a truly exceptional memory. After one
presentation, S. would remember lists containing dozens of items, recite them
forward or backward, and still retain the information 15 years later. But there was a
drawback: No matter how hard S. tried, he could not forget. Images of letters,
numbers, and other items of trivia were so distracting that he had to quit his job and
support himself by entertaining audiences with his feats of memory. Sometimes it is
better to forget—which is why some psychologists have suggested, and
neuroscience supports, the paradoxical conclusion that forgetting is an adaptive,
economical aspect of human memory (Bjork & Bjork, 1996; Schacter, 1999; Wimber,
Alink, Charest, Kriegeskorte, & Anderson, 2015).
The Forgetting Curve
Memory failure is a common experience in everyday life (see Table 6.2). If we
could all get paid $1 for each item we forgot, we would be wealthy. To measure the
rate at which information is forgotten, Ebbinghaus (1885/1913) tested his own
memory for nonsense syllables after intervals ranging from 20 minutes to 31 days. As
shown in the forgetting curve plotted in Figure 6.18, Ebbinghaus found that there
was a steep loss of retention within the first hour, that he forgot more than 60 percent
of the items within 9 hours, and that the rate of forgetting leveled off after that. How
quickly we forget.
forgetting curve. A consistent pattern in which the rate of memory loss for input
is steepest right after input is received and levels off over time.
Table 6.2
Note: Subjects responded on the following scale: 1 = never in the last six
months, 2 = once in six months, 4 = once a month, 5 = more than once a month,...
9 = more than once a day.
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Description
Figure 6.18 The Ebbinghaus Forgetting Curve Sources: Adapted from
Ebbinghaus (1897, 1908).
The Ebbinghaus forgetting curve shows a rapid loss of memory for meaningless
nonsense syllables. Does it apply to real-life memories as well? Bahrick (1984) tested
nearly 800 English-speaking adults who took Spanish in high school. Depending on
the subject, the interval between learning and being tested ranged from 0 to 50 years.
Compared to students who had just taken the course, those who were tested two to
three years later had forgotten much of what they learned. After that, however, scores
on vocabulary, grammar, and reading-comprehension tests stabilized—even among
people who had not used Spanish for 40 or 50 years (illustrated in Figure 6.19). A
similar pattern was also found for the retention, for up to 12 years, of material learned
in a college psychology course (Conway, Cohen, & Stanhope, 1991). In one study,
Dutch researchers found that people remembered the street names from their
elementary school neighborhoods up to 71 years later (Schmidt, Peeck, Paas, & van
Breukelen, 2000). These kinds of impressive results have led Bahrick to argue that
such knowledge may enter a permastore—a term he coined to describe permanent,
very-long-term memory for well-learned material.
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Description
Figure 6.19 Long-Term Forgetting Curve Source: Bahrick, H. P. (1984). Semantic
memory content in permastore: Fifty years of memory for Spanish learned in school.
Journal of Experimental Psychology: General, 113(1), 1–29.
It’s interesting that although this very-long-term curve is not identical to that
reported by Ebbinghaus, there are similarities. Based on a summary analysis of 210
post-Ebbinghaus studies, David Rubin and Amy Wenzel (1996) concluded that his
classic forgetting curve describes a consistent and lawful pattern of human retention
and forgetting. They also raise the possibility that we may have several long-term
memory stores corresponding to different periods of time (Rubin, Hinton, & Wenzel,
1999).
What’s Your Prediction?
Do you remember the study discussed earlier about the college students who
used encoding strategies to increase their recalled digit span from 7 items to 80?
Dario Donatelli was one of the students in this famous experiment, and 30 years later,
Donatelli was assessed again for how many digits he could remember (Yoon,
Ericsson, & Donatelli, 2018). Make a prediction about how many digits Donatelli could
remember on the first try. Now, reflect on why you chose that number. Next, make a
prediction about how many digits he could recall after three days of practice. Again,
reflect on why you chose that number. The results? On the first day of testing, he
could recall 10 digits but on the third day of testing, Donatelli could recall 19 digits.
Not bad, considering that the typical number of items we can retain in working
memory is seven plus or minus two! What encoding strategies did he use as a 50something-year-old participant? Donatelli used chunking and rehearsal, just as he
was taught to use as a 20-something-year-old participant. Donatelli demonstrated
“retention of different aspects of exceptional memory skill” (Yoon et al., 2018, p. 895)
but wasn’t even close to his former glory of 80 digits. The published study, which
included Donatelli as an author (Yoon et al., 2018), paid homage to Ebbinghaus by
stating that Donatelli’s results support the learning curve: as expected, “acquired
memory associations decrease[d] over the time of disuse” (p. 898). Without
consistent practice, the exceptional memory skills that Donatelli learned 30 years
earlier were no longer refined.
Why Do People Forget?
Knowing the rate at which information is lost is just the first step. The next
important question is: Why? Do memory traces fade with time? Are they displaced by
newer memories? Or do memories get buried, perhaps blocked by unconscious
forces? As we’ll see, forgetting can result from one of four processes: a lack of
encoding, decay, interference, or repression. In the first two, the forgotten information
is simply not in long-term-memory storage. In the second two, the memory may exist,
but it is difficult, if not impossible, to retrieve.
Lack of Encoding.
Do you know what an American penny looks like? Would you recognize one if you
saw it? If you were born in the United States, you have looked at, held, and counted
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thousands of pennies in your life. Yet many people cannot accurately draw one from
memory, name its features, or distinguish between a real penny and a fake. Look at
the coins in Figure 6.20. Do you know which is the real one? Raymond Nickerson
and Marilyn Adams (1979) presented this task to college students and found that 58
percent did not identify the right coin. The reason for this result is not that the
subjects forgot what a penny looks like—it’s that the features were never encoded
into long-term memory in the first place. And why should they be? So long as you can
tell the difference between pennies and other coins, there is no need to attend to the
fine details. The penny is not the only common, everyday object whose features we
fail to notice. People also have difficulty recalling the features of a dollar bill, a
computer keyboard, and the letters associated with each number on a phone keypad
—objects we look at and use all the time (Rinck, 1999).
Description
Figure 6.20 Can You Recognize a Penny?
Source: Raymond S. Nickerson, Marilyn Jager Adams, Long-term
memory for a common object, Cognitive Psychology, Volume 11, Issue 3,
1979, Pages 287-307.
When it comes to encoding information, people can be so profoundly absentminded that they exhibit “change blindness,” a failure to detect changes that take
place in their presence. In an astonishing demonstration of this phenomenon, Daniel
Simons and Daniel Levin (1998) had a research assistant approach people on a
college campus and ask for directions. While they were talking, two men walked
between them holding a door that concealed a second assistant. With the subject
screened from view, the two assistants switched places so that when the men
carrying the door passed, subjects found themselves talking to a different person. Did
subjects notice the switch? Would you have noticed it? Remarkably, out of 15
subjects who were tested, only 7 noticed the change. Other studies, too, have shown
this type of visual forgetting from a lack of attention (Simons, 2000), which is why
some researchers refer to this phenomenon as “inattentional blindness.”
Decay.
The oldest theory of forgetting is that memory traces erode with the passage of
time. But there are two problems with this simple explanation. One is that there is no
physiological evidence of decay that corresponds to the fading of memory. The
second is that time alone is not the most critical factor. As we saw earlier, memory for
newly learned nonsense syllables fades in a matter of hours, but a foreign language
learned in high school is retained for many years.
The key blow to the decay theory of forgetting was landed in 1924 by John
Jenkins and Karl Dallenbach. Day after day, these researchers presented nonsense
syllables to two subjects and then tested their memory after 1, 2, 4, or 8 hours. On
some days, the subjects went to sleep between learning and testing; on other days,
they stayed awake and kept busy. The subjects recalled more items after they had
slept than when they were awake and involved in other activities. Jenkins and
Dallenbach (1924) concluded that “forgetting is not so much a matter of the decay of
old impressions and associations as it is a matter of interference, inhibition, or
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obliteration of the old by the new” (p. 612). To minimize forgetting, students may find
it helpful to go to sleep shortly after studying, thus avoiding “new information” (Fowler,
Sullivan, & Ekstrand, 1973).
The correctly drawn penny is shown in (A).
Interference.
By showing that memory loss may be caused by mental activity that takes place
when we are awake, Jenkins and Dallenbach’s study suggested a third explanation of
forgetting—that something learned may be forgotten due to interference from other
information. As summarized in Figure 6.21, there are two kinds of interference. In
proactive interference, prior information inhibits our ability to recall something new.
If you try to learn a set of names, formulas, phone numbers, or glossary terms, you
will find it more difficult if you had earlier studied a similar set of items. Many years
ago, Underwood (1957) found that the more nonsense-syllable experiments subjects
had taken part in, the more forgetting they exhibited in a brand new study.
proactive interference. The tendency for previously learned material to disrupt
the recall of new information.
Description
Figure 6.21 Interference and Forgetting iStock.com/YinYang;
iStock.com/georgeclerk
A related problem is retroactive interference, whereby new material disrupts
memory for previously learned information. Thus, subjects in various experiments are
at least temporarily less likely to recognize previously seen pictures of nature scenes,
faces, and common objects if they are then exposed to similar photographs before
being tested (Chandler, 1991; Wheeler, 1995; Windschitl, 1996). One learning
experience can displace—or at least inhibit—the retrieval of another. That is why
Mercer (2014) and Schlichting and Bäuml (2017) suggest people take a break before
participating in a task that could interfere with newly learned material. In Mercer’s
(2014) study, English-speaking individuals trying to learn Icelandic words were given
or not given the opportunity to take such a break. Those who did take a break had a
reduced chance of forgetting the words, compared to those who did not. Schlichting
and Bäuml (2017) found similar results in memory performance for people who spent
some “passive” time with neutral stimuli—music and pictures—after learning. This
type of forgetting is biologically supported in animal models by the previously
discussed Cai and colleagues (2016) research on CA 1 neurons.
retroactive interference. The tendency for new information to disrupt the
memory of previously learned material.
Repression.
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More than 100 years ago, Sigmund Freud, the founder of psychoanalysis,
observed that his patients often could not recall unpleasant past events from their
own lives. In fact, he observed, they would sometimes stop, pull back, and lose their
train of thought just as they seemed on the brink of an insight. Freud called this
repression, and he said it was an unconscious defense mechanism that keeps painful
personal memories under lock and key—and out of awareness. When we discuss
psychological disorders, we will learn that people who suffer childhood traumas such
as war, abuse, and rape sometimes develop dissociative disorders characterized by
apparent gaps in explicit memory. Repression has never been demonstrated in a
laboratory setting, but psychotherapy case studies suggest that memories can be
repressed for long periods of time and recovered in therapy. As we’ll learn later in this
chapter, however, it is difficult in actual cases to distinguish between dormant
memories of true events and falsely constructed memories of experiences that never
occurred (Baioui, Ambach, Walter, & Vaitl, 2012; Loftus, 1993a; Read & Lindsay,
1997). Although Baioui and colleagues (2012) found that false memories can be
detected with physiological feedback via skin conductance recordings, the findings
should be considered with caution, especially given that similar physiological
measurements to help differentiate between true and false statements—such as a lie
detector test—have failed in the past.
LEARNING CHECK
Forget Me Knots
Let’s see what you remember about forgetting. Match each phenomenon in the
left column with the cause or description most closely associated with it.
(Answers: 1. d; 2. b; 3. e; 4. a; 5. g; 6. f; 7. c.)
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Yanjaa Wintersoul is a Mongolian-Swedish memory athlete. As one of the world’s
best, Yanjaa has frequently demonstrated her memory prowess for large audiences.
One demonstration was for the furniture company Ikea. In the span of one week,
Yanjaa memorized all 328 pages of the Ikea catalogue, down to the color of the
model’s glasses and names of the books on the shelves!
AP Photo/Albin Lohr-Jones
Reconstruction
Up to now, we have likened human memory to a computer that faithfully encodes,
stores, and retrieves information from the recent and distant past. Clearly, however,
there is more to the story. As we’ll see, remembering is an active process in which we
reconstruct memories according to our beliefs, wishes, needs, and information
received from outside sources.
In 1932, Frederick Bartlett asked British college students to recall a story taken
from the folklore of a Native American culture. He found that although they correctly
recalled the gist of this story, they changed, exaggerated, added, and omitted certain
details—resulting in a narrative that was more coherent to them. Without realizing it,
subjects reconstructed the material to fit their own schemas, a term that Bartlett used
to describe the preconceptions that people have about persons and situations. Other
researchers have replicated this result more recently using the same Native
American story (Bergman & Roediger, 1999) and lists of words (Roediger, Meade,
Gallo, & Olson, 2014).
schemas. In Piaget’s theory, mental representations of the world that guide the
processes of assimilation and accommodation.
It’s now clear that schemas distort memory, often by leading us to fill in missing
pieces. Research by Helene Intraub and others (1998) illustrates the point. In a series
of studies, they showed people close-up photographs of various scenes—such as a
telephone booth on a street corner, a basketball on a gym floor, and a lawn chair on a
grassy field. Consistently, subjects who were later asked to recall these scenes
mentally extended the borders by reporting or drawing details that were not in the
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pictures but might plausibly have existed outside the camera’s field of view (illustrated
in Figure 6.22). Why? It appears that the scenes activated perceptual schemas that
led subjects over time to insert new details into memory.
Figure 6.22 Perceptual Schemas Source: Intraub, H., Gottesman, C. V., & Bills,
A. J. (1998). Effects of perceiving and imagining scenes on memory for pictures.
Journal of Experimental Psychology: Learning, Memory, and Cognition, 24(1), 186–
201. https://doi.org/10.1037/0278-7393.24.1.186
iStock.com/lakshmiprasad S
There are many other examples of how schemas influence memory. In one study,
subjects were left waiting alone in a small cluttered room that the experimenter called
an “office.” After 35 seconds, subjects were taken out and asked to recall what was in
the room. What happened? Nearly everyone remembered the desk, chair, and
shelves, objects typically found in an office. But many of the subjects also mistakenly
recalled seeing books—items that fit the setting but were not actually present (Brewer
& Treyens, 1981). Our schemas are sometimes so strong that an object that does not
belong becomes particularly memorable. After spending time in an office, people are
more likely to remember the presence of toy trucks, blocks, and finger paints than of
textbooks, a laptop, and a coffee mug. But they are also more likely to imagine the
existence of office objects that fit the setting but were not present (Lampinen,
Copeland, & Neuschatz, 2001; Pezdek, Whetstone, Reynolds, Askari, & Dougherty,
1989). Neuroscientists have wondered what parts of the brain are activated when
people are tasked to reconstruct a memory using schemas (Kurkela & Dennis, 2016).
Webb and colleagues (2016) found that the visual cortex and hippocampus were
more active during schematic recollection.
The Misinformation Effect
Memory is an active construction of the past—a construction that alters reality in
ways that are consistent not only with prior expectations but also with postevent
information. Consider the plight of those who witness crimes. Afterward, they talk to
each other, read about it on Twitter, and sometimes even watch coverage via social
media. By the time these witnesses are questioned by authorities, one wonders if
their original memory is still “pure,” uncontaminated by postevent information. How
good are people at preventing postevent contamination? How can a person be a
good eyewitness to a crime?
According to Elizabeth Loftus (1979), for most eyewitnesses, their memories are
probably contaminated. Using her studies of eyewitness testimony, Loftus proposed a
theory of reconstructive memory. After people observe an event, she said, later
information about the event—whether it’s true or not—becomes integrated into the
fabric of their memory.
A classic study by Loftus and colleagues (1978) illustrates what has been called
the misinformation effect. In that study, they presented subjects with a slide show in
which a red car hits a pedestrian after turning at an intersection. Subjects saw either
a STOP sign or a YIELD sign in the slides (illustrated in Figure 6.23), but then
embedded in a series of questions they were asked was one that implied the
presence of the other sign (“Did another car pass the Datsun as it reached the ___
sign?”). The result: The number of subjects who later “recognized” the slide with the
wrong traffic sign increased from 25 percent to 59 percent. Other studies soon
confirmed the effect. Researchers thus misled subjects into recalling hammers as
screwdrivers, Coke cans as cans of peanuts, breakfast cereal as eggs, green objects
as yellow, a clean-shaven man as having a mustache, and a bare-handed man as
wearing gloves. To make matters worse, these subjects are often quick to respond
and confident in the accuracy of these false memories (Loftus, Donders, Hoffman, &
Schooler, 1989).
misinformation effect. The tendency to incorporate false postevent information
into one’s memory of the event itself.
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Figure 6.23 Misinformation Effect iStock.com/Brilt; iStock.com/Brilt
This provocative theory has aroused controversy. Does misinformation
permanently impair a witness’s real memory, never to be retrieved again (Belli,
Lindsay, Gales, & McCarthy, 1994; Weingardt, Loftus, & Lindsay, 1995)? Or do
subjects merely follow the experimenter’s “suggestion,” leaving a true memory intact
for retrieval under other conditions (Dodson & Reisberg, 1991; McCloskey &
Zaragoza, 1985)? Either way, an important practical lesson remains: Whether
witnesses’ memories are truly altered or not, their reports of what they remember are
at risk for bias by postevent information. But research by Hoscheidt and colleagues
(2014) gives us hope. This group of psychologists randomly assigned participants to
either a stressful and negative situation, or a control and negative situation, and then
measured their memory performance. Participants under stress had significantly
better memory performance than control subjects. Specifically, participants who
reported high arousal during the stressful condition were less likely to endorse false
information.
Does this mean that if you are subjected to high levels of stress during an
aversive event, your memory is protected from misinformation? Not necessarily.
Other research on stress and the misinformation effect has produced findings in the
opposite direction (Moran, Southwick, Steffian, Hazlett, & Loftus, 2013). Why the
inconsistencies? Shields and colleagues (2017) desired to complete a thorough
review to provide an answer. Their conclusion was that the timing and context of the
lab-induced stress affected whether or not memory was helped or hindered. For
example, in studies where stress occurred during retrieval, memory was hindered. If
the study tasks were directly related to the stressor, and there was not much of a
delay between the stressor and encoding, memory was helped. Furthermore,
hormonal contraceptives seemed to play a protective role in women’s memory
performance when under stress.
This review by Shields and colleagues (2017) suggests that many factors
influence the role stress plays in encoding and retrieval. Mind you, these participants
were stressed and exposed to negative stimuli in a laboratory setting. They were not
victims of a crime. Cases like that of Ronald Cotton and Jennifer Thompson provide
clear examples of memory gone awry due to postevent information. Jennifer falsely
identified Ronald as her rapist from a series of photographs and a lineup, even
though she purposefully focused her attention on her rapist’s face and characteristics
during the assault (Innocence Project, 2017). When presented in court with the face
of her actual rapist, Bobby Poole, Jennifer still misidentified Ronald as her rapist. She
also believed she had never seen Bobby before. DNA evidence exonerated Ronald
Cotton 10 years later, and Bobby Poole was convicted of the rape, demonstrating that
the misinformation effect is real, is not perfectly protected by stress, and can have
devastating results.
The Creation of Illusory Memories
The misinformation effect led cognitive psychologists to discover that people
sometimes create memories that are completely false. At the start of this chapter, we
learned that people who heard a list of sleep-related words (e.g., bed, yawn) or
music-related words (e.g., jazz, instrument) were often convinced just minutes later
that they had also heard sleep and music—words that fit their schemas but were not
actually on the lists (Roediger & McDermott, 1995). But recalling words from a list is a
low-stakes issue. What about planting false memories like one can plant false
evidence? Strange and colleagues (2008), Wade and colleagues (2002), and
Conway (2013) presented experimental evidence of how easy it can be to mislead
adults about their own childhood experiences. In almost 40 percent of participants in
the Strange and colleagues (2008) study, false childhood memories were
successfully implanted.
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