The Effects of Distinctive Processing and Sleep Deprivation on False Memory

SLEEP, FALSE MEMORY, AND DISTINCTIVE PROCESSING

1

The Effects of Distinctive Processing and Sleep Deprivation on False Memory

Marissa Bell, Zac Shaiken, and Riah Sorn-ampai

Whitman College


2

Abstract

The present study explores the relationship between sleep deprivation and false

recognition. Sixty-three participants were administered the original Deese-Roediger McDermott

(DRM) procedure, or a modified DRM procedure in which each word was presented in a

distinctive font. Additionally, participants’ sleep data was collected using an actigraphy watch,

along with other sleep measures in order to determine their level of sleep deprivation. The

current study found that participants in the distinctive font condition falsely recognized

significantly fewer critical lures than participants in the normal font condition. While previous

research indicates that sleep deprivation correlates with higher rates of false recognition, the

current study found no significant differences in the rates of false recognition between sleep

deprived and non-sleep deprived individuals. These results suggest that distinctive processing

may be an effective psychological tool for augmenting memory. Additional research needs to be

done to further understand the relationship between sleep deprivation and false memory.

Keywords: sleep deprivation, false recognition, distinctive processing, memory, DRM


3

The Effects of Distinctive Processing and Sleep Deprivation on False Memory

Chronic sleep loss is a widespread problem in today’s society (Strine & Chapman, 2005).

According to the Center for Disease Control, more than one third of adults report that they

regularly receive inadequate sleep, which has psychological and physiological consequences

(Liu et al., 2016). For example, feelings of anger, sadness and anxiety have shown to be

associated with poor sleep quality (Thomsen, Mehlsen, Christensen & Zachariae, 2003).

Insufficient sleep has also been found to coexist with heart disease, kidney disease, high blood

pressure, and obesity (Prince & Abel, 2013). In addition to these negative effects of sleep

deprivation, a large body of literature has shown that a lack of sleep impairs cognitive functions.

More specifically, executive functions related to decision-making and attention is impaired with

sleep deprivation, promoting the creation of false memories (Killgore, 2010).

Before reporting on our experiment, we will first discuss how sleep and memory are

connected. This paper will then focus on how sleep is important for cognitive processes,

followed by an explanation on how a lack of sleep may result in inaccurate representations of

memory. Finally, we will discuss how distinctive processing may help in reducing false memory.

Role of Sleep in Memory

Psychologists have classified human memory into two distinct categories: procedural (or

implicit) and declarative (or explicit) memory. Declarative memory refers to memories of facts

and events that can be consciously recalled (Ullman, 2004). When people encode something

new, this novel information becomes meaningful, solidifying and sticking in our brains through a

process known as memory consolidation (McGaugh & Hertz, 1972). Memories can be

understood as webs of neural connections (Medina, 2009). During consolidation, more entry

points to these webs of connections are created, allowing for easier access to memories. These


4

webs of connections, made up of neural pathways, are also strengthened during sleep through a

process called myelination (McGaugh, 2000). During this process, an insulating sheath of myelin

is created around neuronal fibers, making activations of neural pathways easier and quicker

(Medina, 2009). In the past, researchers believed that memory consolidation took place with the

mere passage of time, however more recent findings suggest that the time spent in sleep also

plays a key role in preserving memory (McGaugh, 2000).

Some of the first evidence for sleep contributing to consolidation came from studies

reporting that sleep deprivation altered the consolidation of declarative memories. In a

pioneering study, participants were able to remember nonsense syllables and short stories much

better after intervals filled with sleep compared to intervals of wakefulness (Jenkins &

Dallenbach, 1924).

Gais and Born (2004) suggested that declarative memory benefits from sleep that is

dominated by periods of slow wave sleep (SWS). Retention of information in declarative

memory has been positively linked to sleep spindles, which occur during SWS. Sleep spindles

are thalamocortical bursts that occur roughly every three to ten seconds during non-REM sleep,

and last for around one to three seconds. Although the precise function of sleep spindles is

unknown, studies suggest that the function of sleep spindles is to preserve sleep by inhibiting

sensory input (Schabus et al., 2004; Yamadori, 1971). This suggestion is supported by Schabus

et al.’s study (2004) which involved giving participants a list of word pairs to memorize and

asking them to recall the pairs after sleep. Participants who had more sleep spindles tended to

recall the paired words better than participants who had fewer sleep spindles. Another study

examined the relationship between declarative memory and SWS by asking participants to watch

a movie and then answer some questions about the film the next morning. The researchers found


5

that sleep spindle density in SWS was strongly and positively correlated to declarative memory

recall (Cox, Hoffman & Talamini, 2012). In other words, participants who experienced dense

sleep spindles in SWS after watching the movie were more likely to retain information and

correctly answer questions about the film the following day compared to participants who did not

experience dense sleep spindles in SWS. These findings imply that a positive correlation exists

between sleep spindles and declarative memory consolidation. However, it remains unknown

whether sleep spindles are a result of thalamocortical encoding and consolidation, or if they are

the catalyst.

More specifically, verbal memory retention has been shown to be connected to sleep

spindle activity, whereas declarative memory for more complex materials seems to depend on

other sleep mechanisms (Clemens, Fabo, & Halasz, 2005). In one study, participants were asked

to study a number of faces with corresponding names. The next morning, they were asked to

recall this information by completing a facial recognition and name recall task. Name recall was

positively correlated with the number of sleep spindles during SWS, whereas facial recognition

was positively correlated to the duration of non-REM sleep (Clemens et al., 2005).

In summary, sleep is vital to the encoding and recall of memory. During sleep, memory

consolidation is enhanced through myelination of neural pathways. Additionally, the generation

of sleep spindles during SWS has been positively correlated to strengthening declarative

memory. Sleep deprivation, then, is thought to negatively affect or inhibit these processes,

potentially resulting in the creation of false memories.

Sleep Deprivation and the Physiology of Cognition

Lack of sleep interferes with the functioning of certain regions in the brain that underlie

cognition. Specifically, sleep deprivation affects parts of the brain responsible for storing


6

memories. Neuroimaging studies have found that activity within the prefrontal cortex declines

following sleep deprivation (Killgore, 2010). The prefrontal cortex supports memory

consolidation by storing memories that are encoded by the hippocampus during sleep (Euston,

Gruber, & McNaughton, 2012). These results affirm what is called the prefrontal vulnerability

hypothesis.

The prefrontal cortex, responsible for executive functioning, creativity and language, is

especially dependent on sleep (Muzur, Pace-Schott, & Hobson, 2002). The prefrontal

vulnerability hypothesis suggests that sleep deprivation significantly impairs cognitive

performance that depends on the prefrontal cortex (Horne, 1993). In order to perform optimally,

the frontal regions of the brain need time to rest during sleep (Muzur et al., 2002). Studies that

examine brain activity during sleep have found that the transition from a wakeful state into non-

REM sleep is characterized by frontal deactivation. With the deepening of non-REM sleep, the

deactivation of the prefrontal cortices deepens (Muzur et al., 2002). This finding suggests that

without sleep, the prefrontal cortex may become overworked, resulting in an impairment of the

cognitive capabilities supported by this region of the brain.

Sleep deprivation also affects the cognitive and physiological processes involved in

memory, such as decreasing working memory capacity (Frenda, Patihis, Loftus, Lewis, & Fenn,

2014). According to Bonnet and Arand (2003), sleep deprivation is associated with unique

patterns of cortisol and noradrenaline secretion. Secretion of both of these hormones is

dependent on rhythmic circadian cues. During sleep deprived or sleep fragmented states, the

secretion patterns of these hormones are disturbed.

Noradrenaline is particularly important to memory consolidation and retrieval processes

(Kim et al., 2015; Prokopová, 2010; Uematsu, Tan, & Johansen, 2015). Specifically,


7

noradrenaline modulates memories and is central in consolidating long-term memories (Gibbs,

Hutchinson, & Summers, 2010). Cortisol helps to encode memories and normal cortisol

secretions have been shown to assist in the encoding of memories (Ackermann, Hartmann,

Papassotiropoulos, de Quervain, & Rasch, 2013). However, elevated cortisol levels interfere with

memory retrieval mechanisms and result in decreased performance on memory tasks

(Ackermann et al., 2013).

Sleep Deprivation and False Memory

A false memory is a distortion of an existing memory, resulting in an erroneous or

confabulated memory representation (Kopelman, 1999). False memories can be measured or

revealed through recall and recognition. False recall is a type of memory distortion whereby an

individual freely recalls information, lacking any prompts or cues, that he or she believes has

been previously presented but was never actually present (Roediger & McDermott, 1995). False

recognition is a type of memory distortion where an individual is presented with a completely

novel stimulus (i.e. unstudied or unlearned) and incorrectly claims that he or she has seen or

encountered it before (Abe et al., 2013). There are two types of false recognition: unrelated and

related false recognition. For example, related false recognition occurs when an individual

falsely recognizes a stimulus that is semantically or visually similar, but not identical, to the

original stimuli. Unrelated false recognition refers to falsely recognizing completely novel

stimuli (Garoff-Eaton, Slotnick, & Schacter., 2006).

Sleep deprivation may also contribute to the creation of false memories by affecting the

ways in which memories are encoded. As described earlier, sleep loss impairs executive

functioning, working memory, problem solving, decision-making and attention, and has been

shown to negatively affect declarative learning and memory (Durmer & Dinges, 2005; Curcio,


8

Ferrara, & De Gennaro, 2006). Specifically, when individuals are sleep deprived they have

decreased attention, impaired working memory and weakened problem solving skills which may

lead difficulties in focusing and selectively processing information (Fougnie, 2008). Therefore,

sleep deprivation at encoding may result in the creation of inaccurate memories that do not

actually represent experienced events. In this way, false memories are created.

Sleep deprivation may promote the creation of false memories at a chemical level.

Learning information increases cAMP chemicals; these chemicals bind to proteins that are

responsible for converting easily altered memories into long-term memories (Prince & Abel,

2013). According to Prince and Abel (2013), there are critical periods of chemical uptake;

inhibiting cAMP uptake during these critical periods can impair memory consolidation. One of

these critical periods occurs during the first few hours of sleep. Thus, if sleep deprivation

overlaps with one of these critical periods, it may promote the creation of false memories by

impairing memory consolidation.

Psychologists have examined false memory in many ways, one of which is by using the

Deese-Roediger-McDermott (DRM) procedure (Roediger & McDermott, 1995). The DRM

procedure creates false memories by presenting participants with a short list of words, all relating

to a specific theme, and participants are asked to remember as many words as possible. The

DRM procedure utilizes both unrelated and related false recognition. All words on the list are

semantically associated with a non-presented word, known as the “critical lure.” Semantically-

related items are intended to encourage participants to falsely recognize the critical lure, whereas

the unrelated distractor items are designed to elicit unrelated false recognition. Typically in both

recognition and recall tests, participants will claim to remember the critical lure just as much as

the words they were actually asked to study (Hunt, Smith, & Dunlap, 2011). When participants


9

are asked to recognize or recall words from the list, individuals who are sleep deprived often

falsely recall the critical lure (Roediger & McDermott, 1995)

The DRM procedure has been used to study the effects of sleep deprivation on false

recall. In one experiment, participants were divided into two groups and administered the DRM

procedure (Diekelmann, Landolt, Lahl, Born & Wagner, 2008). Participants first studied multiple

lists of semantically-related words. After the study phase, one group slept while the other group

remained awake all night. The following morning, both groups recalled words that they

remembered studying on the list. The group that was deprived of sleep had a higher rate of false

recall than the group that slept, suggesting that sleep deprivation at retrieval is associated with

more instances of false recall (Diekelmann et al., 2008).

Role of Distinctive Processing in False Memory

One mechanism that can assist in memory retrieval is distinctive processing at the time of

encoding. Distinctive processing is defined as the processing of differences within the context of

similarity (Hunt et al., 2011). Distinctive processing consists of two different components: item-

specific processing and relational processing. Relational processing can be understood as the

processing of similarities. Relational processing occurs when participants notice a semantic

relationship between words in DRM lists, because all words within the presented list are related

to the same theme. Relational processing leads to the encoding of semantically associated items

being grouped together in memory instead of as individual, distinct items. In contrast, item-

specific processing refers to processing distinctions between items grouped together in memory.

This form of processing involves focusing on differences between the studied words in the DRM

procedure that could allow the participant to better distinguish between studied words and non-


10

studied words. Together, relational processing and item-specific processing constitute distinctive

processing.

Arndt and Reder (2003) carried out a study examining the effects of distinctive

processing on memory using the DRM procedure. Each of the twelve semantically associated

words that participants were asked to study were presented in a separate, unique font.

Researchers believed that presenting each word in a unique font would increase distinctiveness

by enhancing the differences between each studied item, consequently decreasing the

participant’s level of false recognition by improving the ability to differentiate studied from

unstudied test items. The results confirmed that when words were presented in a unique font,

individuals were more likely to recognize presented words, and less likely to falsely recognize a

critical lure, compared to individuals who were asked to study words that appeared in the same

font.

Another study examined the effects of distinctive processing on false memory using the

DRM procedure (Hunt et al., 2011). Participants were randomly assigned to either an intentional

memory study task, or one of two orienting tasks: pleasantness rating or vowel counting. The

participants were then presented six lists of words from the DRM procedure. Participants in the

intentional memory group were instructed to pay attention to the presented words and try to

remember them. Individuals in the pleasantness rating group were asked to rate the pleasantness

of each word using a numerical scale. Those in the vowel counting group were asked to count the

number of vowels within each word. Orienting tasks encourage an association between a word

and a specific type of processing (such as a rank of pleasantness), which is thought to increase

distinctive processing by increasing the perceived differences between the words, and therefore

decrease false recognition. Participants who completed an orienting task for each word had less


11

false recognition of critical lures than individuals in the intentional memory group (Hunt et al.,

2011). Additionally, Hunt et al.’s (2011) study found that the orienting task condition also

increases hits of studied items; the pleasantness rating orienting task elicited higher rates of hits

than individuals in the intentional memory group. These results are consistent with Arndt and

Reder’s findings.

The results from both Arndt and Reder’s (2003) font study and Hunt et al.’s (2011)

orienting task study may be explained by the presence of distinctive processing. It is possible that

the manipulation of font and the presence of an orienting task in each respective study

encouraged participants’ item-specific processing and discouraged relational processing. The

idea that enhancing item specific processing reduces false memory is supported by a study

conducted by McCabe and colleagues (2004), who asked participants to study a word list using

an item-specific strategy to enhance the differences between words. Specifically, participants

were asked to think of the unique characteristics of each word—the characteristics that

differentiate the words from one another. Participants who used item-specific strategies

recognized significantly fewer critical lures than a control group who completed the DRM

procedure without using an item-specific strategy (McCabe, Presmanes, Robertson, & Smith,

2004). These results suggest that unique, item-specific details that are encoded with each word

can augment discrimination between studied items and critical lures.

The Present Study

The present study is concerned with examining the effect of sleep deprivation on

distinctive processing. As discussed earlier, sleep deprivation at retrieval increases potential for

false memory. However, as previously described, visual distinctive processing has been shown to

reduce false recognition. Therefore, we hypothesize that, (a) relative to a non-sleep deprived


12

group, a sleep deprived group will have higher rates of false recognition in a standard DRM

procedure that does not contain distinctive visual information, (b) a non-sleep deprived group

will have lower rates of false recognition in a modified DRM procedure compared to a non-sleep

deprived group that receives the standard DRM procedure, and that (c) a sleep deprived group

who receives the modified DRM procedure will receive similar scores to a non-sleep deprived

group that receives the standard DRM procedure.

Method

Participants

We recruited 67 participants from Whitman College in Walla Walla, Washington.

Participants were recruited by word of mouth, email, and through introductory psychology

classes. After exclusionary screening, data from four participants were discarded due to either

missing information from their sleep log, or errors that occurred during the study and test

portions of the experiment. We used data from the remaining 63 participants. We asked

participants to report their age, preferred gender, ethnicity, how often they drink coffee, and

whether they had taken anything within the past three days that could interfere with sleep (either

by inducing or preventing it, including drinking to intoxication). Participants were between 18

and 24 years old. 48 females and 15 males participated in our study. Of these participants,

65.08% were Caucasian, 9.52% were Asian, 9.52% were Caucasian-Asian, 4.76% were

Hispanic, 1.59% were Caucasian-Hispanic, 1.59% were African American, and 7.94% chose not

to provide their race.

Materials and Measures

Original Deese-Roediger-McDermott Procedure Study List


13

The Deese-Roediger-McDermott (DRM) procedure is designed to measure false memory

of words from a word list. Each list in the DRM procedure contains fifteen words, all

semantically related to an unpresented word known as the critical lure. Examples of words

include snow, ice, and freeze, relating to the critical lure cold. We selected twelve DRM word

lists that were found to be the most effective in eliciting false recognition (Stadler, Roediger, &

McDermott, 1999). We divided our twelve word lists into two sets of six lists (see Appendix C).

Each participant was assigned to study one set of six lists; the remaining set of six lists were used

as unstudied words on the recognition test. The assignment of sets to study conditions was

counterbalanced across participants. Participants were shown the set of words all in the same

font, and were then given a recognition test in which they are asked to indicate which words they

remembered learning (Roediger & McDermott, 1995).

Modified Deese Roediger-McDermott Procedure Study List

The modified DRM procedure follows the original DRM procedure, except each item on

the word list will be presented in a unique font at study. During the recognition test, when

participants are asked to indicate whether they remember or do not remember the word being

presented, each item will appear as it did in the studied word list, in its unique font. The fonts

chosen for this experiment are unusual and unlikely to have been previously encountered. By

selecting unique fonts that do not resemble what one typically sees in everyday life, the items are

made more distinct (Arndt & Reder, 2003).

Recognition Test List

Two separate recognition tests were created for the original DRM study list and the

modified DRM study list, containing the words in distinctive fonts. The recognition test included

the first and seventh word from the six studied lists, the first and seventh word from the six


14

unstudied lists, and the critical lures from both the studied and unstudied lists. In total,

participants were shown 36 words rather than 192 words on the recognition test due to concerns

regarding the length of the experiment.

Epworth Sleepiness Scale

The Epworth Sleepiness Scale (ESS) is a measure of daytime sleepiness (Appendix A).

The ESS is an 8-item self-response questionnaire. Each item asks participants to rate their

chances of falling asleep in different situations on a scale between 0 and 3, with 0 being would

never doze and 3 being high chance of dozing. Situations include sitting and talking to someone,

in a car while stopped for a few minutes in traffic, and watching television. The scores for each

response are added together to yield a final ESS score between 0, indicating no daytime

sleepiness, and 24, indicating a high level of daytime sleepiness (Johns, 1991). The internal

reliability of this test is high, with a Cronbach alpha of 0.88, as cited in Johns’ study (1992).

Pittsburgh Sleep Quality Index

The Pittsburgh Sleep Quality Index (PSQI) is a measure of sleep quality (Appendix B). It

is a 9-item self-response questionnaire that measures sleep quality during the past month.

Questions are divided into seven subscales, which are summed to yield a global PSQI score

between 0 and 21. A global score of 21 indicates the poorest quality sleep and 0 indicates the

best quality sleep. Responses to each item are made on a scale ranging from 0 and 3, where 0 is

not during the past month and 3 is three or more times a week. Items include during the past

month, how often have you taken medicine to help you sleep? and during the past month, how

often have you had trouble sleeping because you cannot get to sleep within 30 minutes? (Buysse,

Reynolds, Monk, Berman, & Kupfer, 1988). Internal reliability of the PSQI is high with a

Cronbach alpha of .80, as cited by Carpenter and Andrykowski (1998).


15

Actigraphy Watch

We used watches that collect actigraphy data to measure the amount of sleep per night

that each participant received over the duration of the study (Core C410 Activity and Sleep

watch; LifeTrak, Newark, CA). The watch uses accelerometers to measure movement which

ceases during sleep. A metastudy combining the results from 70 studies found consistently high

levels of agreement (over 80 percent) between sleep data collected through actigraphy watches

and sleep data formally collected using polysomnography in a monitored sleep lab, confirming

the validity of the watch (Morgenthaler et al., 2007).

Procedure

Data collection for each participant lasted four days, however the total time of active

participant engagement lasted approximately 45-60 minutes (Figure 1). On the first day of the

study, participants were asked to read an informed consent form and sign the document if they

chose to participate in the study. Next, they were given an actigraphy watch and a sleep log

(Figure 2). Participants were encouraged to wear the watch all day, but were told that it was only

necessary to wear the watch when they slept. Participants were asked to also manually record the

time that they woke up and went to bed in a sleep log for each day of the study, acting as

confirmation to the actigraphy watch sleep data. Participants were also asked to record the times

of any naps they took during the day, and number of cups of caffeine they consumed. On the

evening of day Day 3, participants met the experimenter in a Maxey Hall classroom and were

randomly assigned to study either the normal DRM, or a modified version of the DRM

procedure. Both DRM sets contained six word lists, each comprised of 15 semantically related

items, totaling 90 words. Each list was prefaced with text stating “list #1” or “list #2. ” A blank

screen appeared for three seconds at the start and the end of each word list. Items in each list


16

were shown on a computer screen for three seconds. A blank screen appeared for a half of a

second between each word. Participants were asked to say each word aloud, confirming that each

item was processed.

On the morning of Day 4, participants completed the recognition portion of the DRM

procedure. Words appeared on the screen until the participant indicated either remembering or

not remembering the word. This response triggered the appearance of the next word. Participants

pressed the slash (/) key, covered by a green sticker, to indicate they remembered studying the

word, or pressed the z key, covered by a red sticker, to indicate they did not remember studying

the word. For the modified DRM procedure, words were presented at test in the same font in

which they were studied. If the word was new, a new font was used. The data from these

questionnaires were used to further confirm a participant as either sleep deprived or non-sleep

deprived. Lastly, participants completed the completed the ESS questionnaire, the PSQI, and a

demographics questionnaire, and returned their actigraphy watches and sleep logs.

Results

Participants were categorized as either sleep deprived or non-sleep deprived using their

actigraphy watch data, and scores from the Epworth Sleepiness Scale and Pittsburgh Sleep

Quality Index. Participants whose actigraphy data indicated that they had slept less than an

average of 8 hours per night met our first criteria of sleep deprivation. A second criterion we

used for categorizing participants was the Epworth Sleepiness Scale. According to the scoring

instructions of the ESS, participants who scored 10 or above were considerably sleepy.

According to the scoring instructions of the PSQI, participants who scored 5 or above were

considered to have poor sleep quality. To be placed in the sleep deprived category, the

participant’s data had to meet two out of three of these criteria. The memory tests measured how


17

many times a participant falsely recalled critical lures related to the studied words, falsely

recalled unstudied words and critical lures, and correctly identified studied words.

First, we considered whether sleep was different among the groups. An independent-

samples t-test was conducted to compare average hours of sleep in sleep deprived (N=27) and

non-sleep deprived (N=38) conditions. There was a significant difference between the average

hours of sleep in sleep deprived (M = 7.40, SD = 1.03) and non-sleep deprived (M = 8.24, SD =

0.55) participants, t(63) = 4.30, p = .01. A second independent-samples t-test was conducted to

compare ESS scores in sleep deprived and non-sleep deprived conditions. There was a

significant difference between ESS scores in sleep deprived (M = 8.85, SD = 3.30) and non-sleep

deprived (M = 5.62, SD = 2.28) groups, t(63) = 4.64, p = .01. An independent-samples t-test was

also conducted to compare PSQI scores in sleep deprived and non-sleep deprived conditions.

There was a significant difference between PSQI scores in sleep deprived (M = 6.00, SD = 1.51)

and non-sleep deprived (M = 4.00, SD = 1.70) groups, t(63) = 4.90, p = .01.

Data from this study were analyzed using 2 (font) x 2 (sleep condition) ANOVAs. We

analyzed false alarms first because false recognition of critical lures differed significantly

between distinctive font (M = 0.62, SD = 0.30) and normal font (M = 0.80, SD = 0.28) groups, as

indicated by a main effect of font, F(1, 61) = 5.95, MSE = 0.09, p = .02, =.09. These

findings replicate those found by Arndt and Reder (2003). However, false recognition of critical

lures did not differ significantly between sleep deprived (M = 0.71, SD = 0.35) and non-sleep

deprived (M = 0.71, SD = 0.27) groups, F(1, 61) = 0.01, MSE = 0.09, p = .93, = .01. There

was also no significant interaction between sleep category and font condition, F(1, 61) = 0.93,

MSE = 0.09, p = .34, = .02.


18

To determine whether this reduction of false recognition extended to other word types,

we analyzed false alarms of non-studied words that were not critical lures and found that they did

not differ significantly between distinctive font (M = .16, SD = 0.13) and normal font (M = 0.21,

SD = 0.15) conditions, F(1, 61) = 2.14, MSE = 0.02, p = .15, = .03. False alarms of non-

studied words also did not differ significantly between sleep deprived (M = 0.18, SD = 0.15) and

non-sleep deprived (M = 0.19, SD = 0.14) groups, F(1, 61) = 0.08, MSE = 0.02, p = .78, =

.01. There was no significant interaction between sleep category and font condition, F(1, 61) =

0.30, MSE = 0.02, p = .58, = .01.

Turning to hits, hits for the first word studied within each list did not differ significantly

between distinctive font (M = 0.87, SD = 0.14) and normal font (M = 0.88, SD = 0.17) groups,

F(1, 61) = 0.03, MSE = 0.03, p = .86, = .01. Hits for first words also did not differ

significantly between sleep deprived (M = 0.88, SD = 0.20) and non-sleep deprived (M = 0.87,

SD = 0.12) groups, F(1, 61) = 0.01, MSE = 0.03, p = .96, = .01. There was also no significant

interaction between sleep category and font condition, F(1, 61) = 0.25, MSE = 0.03, p = .62, =

.01.

Similarly, hits for the seventh word studied within each list did not differ significantly

between font (M = 0.79, SD = 0.24) and normal font (M = 0.74, SD = 0.19) conditions, F(1, 61)

= 0.71, MSE = 0.05, p = .40, = .01. Hits for seventh studied words also did not differ

significantly between sleep deprived (M = 0.77, SD = 0.22) and non-sleep deprived (M = 0.76,

SD = 0.21) groups, F(1, 61) = 0.02, MSE = 0.05, p = .88, = .01. Finally, there was no


19

significant interaction between sleep category and font condition, F(1, 61) = 0.20, MSE = 0.05, p

= .66, = .01.

Discussion

In conducting this study, we hoped to examine the interaction between sleep deprivation,

distinctive processing and false memory. We examined these three factors by monitoring

participants’ total hours of sleep, sleep quality, sleepiness levels, and administering the DRM

procedure in which participants were asked to study lists of words and then complete a

recognition test. We hypothesized that sleep deprivation would increase false recognition, and

that distinctive processing would decrease false recognition. In addition, we hypothesized that

the increase in false memory attributed to sleep deprivation would be attenuated by distinctive

processing. Our results partially confirm our hypotheses. Distinctive fonts significantly reduced

false recognition. Individuals who were shown words in distinctive fonts were less likely to

falsely recognize the semantically associated critical lure. This finding suggests that distinctive

processing is effective in reducing false recognition. Sleep had no significant effect on false

recognition. Sleep deprived and non-sleep deprived participants did not differ significantly in

correctly rejecting the critical lure.

Although much research indicates that sleep deprivation promotes false memories, some

studies have also found that sleep may enhance false memories (Diekelmann et al., 2008);

Diekelmann et al., 2009). When we sleep, memories are consolidated and organized. During

consolidation, these memories can be qualitatively changed, resulting in false memory (Payne et

al., 2009). In a study performed by Diekelmann, Born, and Wagner (2009), participants were

presented with a list of words to study. After studying the list, they either slept (non-sleep

deprived), stayed awake during the night (sleep deprived), or were awake during the day


20

(daytime wakefulness). Both the non-sleep deprived and the sleep deprived group falsely

recalled significantly more critical lures than the daytime wakefulness group. In addition,

participants who were non-sleep deprived recalled more critical lures than both of the sleep

deprived and daytime wakefulness groups.

These findings suggest that memories also become distorted during the memory

consolidation process that occurs during sleep, thereby promoting the creation of false memories.

These seemingly contradictory findings might also be explained through procedural differences.

In the study explained above, Diekelmann et al. (2009) examined false memory through recall

rather than recognition. In addition, sleep was manipulated after learning the lists. In our study,

participants were given a recognition test, rather than a recall test where one must freely recall a

word without any prompting. In order to classify participants as either sleep deprived or non-

sleep deprived, we examined individuals’ average sleep data from three days before the encoding

test up until the morning of the recognition test. In contrast, the Diekelmann study considered

sleep only during the night after encoding and before the recall test. These differences in

procedure may explain why our results differ. Timing of sleep deprivation could affect false

memory. An individual who is sleep deprived during both encoding and retrieval may be

affected differently compared to someone who only experiences sleep deprivation during the

retrieval stage. The amount of sleep deprivation that an person experiences could also affect false

memory.

Limitations

There were several limitations to our study. Individual differences in the amount of sleep

that a person needs per night makes sleep deprivation difficult to quantify (Mercer, Merrit, &

Cowell, 1998). Some participants may have felt well rested after sleeping for six hours, whereas


21

others may have required nine hours of sleep in order to feel well rested. Additional research is

needed to better quantify sleep deprivation (Van Dongen, Vitellaro, & Dinges, 2005). We

attempted to account for this difficulty by using a sleepiness scale and sleep quality index in

addition to actigraphy data. Future research could improve upon this by replacing actigraphy data

with EEG data and controlling for caffeine intake.

Initially, we intended to exclude participants depending on their levels of caffeine intake.

However, we ultimately decided that excluding their data would significantly reduce our sample

size, thereby reducing the statistical power of our analyses. As a result, overlooking that

information could have led us to wrongly categorize a participant as sleep deprived or non-sleep

deprived.

Samples selected on college campuses are generally not representative of the larger

population, as students generally differ in age, socioeconomic status, education, and ethnicity

(Okazaki & Sue, 1995). All of the data from our research was collected from a majority of

Caucasian students attending an expensive liberal arts college in the Pacific Northwest. As a

result, our data does not truly reflect the general population. With our narrow, skewed sample

size it is difficult to determine the external validity of our results.

Strengths

Our results indicate that distinctive processing plays a significant role in reducing false

memory. Individuals who received semantically similar word lists in which the words were

presented in a unique font were more likely to correctly reject the critical lure. Participants who

were presented with words in normal fonts were more likely to falsely identify the critical lure as

a previously studied word. Our results replicate research conducted by Arndt and Reder (2003),

which indicate that distinctive fonts reduce false recognition.


22

Even though we were unable to implement a more rigorous sleep study and measure

participants’ sleep activity more precisely through an electroencephalogram, we included ample

sleep measures. In addition to collecting a total number of hours slept through an actigraphy

watch, we also administered one scale measuring participants’ level of sleepiness and another

examining their sleep quality. Together, these three measures examined sleep deprivation in a

holistic, comprehensive way.

Despite the time commitment and length of our study, we were able to recruit a fairly

large number of students to participate. Our study required a large number of participants in

order to have relatively equal numbers of participants in each condition. As we were able to

recruit 63 participants, a sufficient number of individuals fell into the sleep deprived and non-

sleep deprived, and font and distinctive font groups, allowing us to adequately analyze our data.

Future Research

Our study supported previous findings suggesting that presenting DRM words in

distinctive fonts elicits lower rates of false recognition than words presented in similar fonts

(Arndt & Reder, 2003). Future research could examine the effect of distinctive processing on an

auditory version of the DRM procedure. Instead of having each word presented in the same

voice, each word could be presented in a unique voice to assess whether an auditory version of

distinctive processing would be effective in reducing false recognition in auditory memories.

Additionally, our study examined the role of distinctive processing in enhancing

declarative memory. Future research on false memory could shift the focus towards examining

whether distinctive processing can impact implicit memory as well. Potential experiments could

examine whether presenting unique stimuli during a procedural learning task had an impact on

later performance. For example, participants could be asked to perform a series of movements


23

(run, jump, walk, etc.). Half of the participants would only be asked to perform the series of

movements, while the other half would be told the series of movements and exposed to a unique

sound for each movement. Analyses could compare the number of errors at testing between the

two groups, and the time it takes each group to complete the series of movements.

Our study concluded that sleep played no significant role in false recognition. Although

our literature review mainly focused on research supporting the claim that sleep deprivation

increases an individual’s susceptibility to false memory, other research has led to different

conclusions. Future research could attempt to further elucidate why some studies indicate that

sleep promotes the creation of false memories, while other studies suggest that sleep deprivation

promotes the creation of false memories.

References

Abe, N., Fujii, T., Suzuki, M., Ueno, A., Shigemune, Y., Mugikura, S., & Mori, E.

(2013). Encoding- and retrieval-related brain activity underlying false


24

recognition. Neuroscience Research, 76, 240-250.

Ackermann, S., Hartmann, F., Papassotiropoulos, A., de Quervain, D., & Rasch, B.

(2013). Associations between basal cortisol levels and memory retrieval in

healthy young individuals. Journal of Cognitive Neuroscience, 11, 1896-1907.

Arndt, J., & Reder, L. (2003). The effect of distinctive visual formation on false

recognition. Journal of Memory and Language, 48, 1-15.

Bonnet, M., & Arand, D. (2003). Clinical effects of sleep fragmentation versus sleep

deprivation. Sleep Medicine Reviews, 7, 297-310.

Buysse, D., Reynolds III, C., Monk, T., Berman, S., & Kupfer, D. (1988). The Pittsburgh

sleep quality index: A new instrument for psychiatric practice and research. Psychiatry

Research, 28, 193-213.

Carpenter, J. S. & Andrykowski, M. A. (1998). Psychometric evaluation of the pittsburgh sleep

quality index. Journal of Psychosomatic Research, 45:1, 5-13.

Clemens, Z., Fabo, D., & Halasz, P. (2005). Overnight verbal memory retention

correlates with the number of sleep spindles. Neuroscience, 132, 529-535.

Cox, R., Hofman, W. F., & Talamini, L. M. (2012). Involvement of spindles in memory

consolidation is slow wave sleep-specific. Learning and Memory, 19. 264-267.

Curcio, G., Ferrara, M., & De Gennaro, L. (2006). Sleep loss, learning capacity, and

academic performance. Sleep Medicine Reviews, 10, 323-337.

Diekelmann, S., Born, J., & Wagner, U. (2009). Sleep enhances false memories depending

on general memory performance. Behavioural Brain Research, 208, 245-249.

Diekelmann, S., Landolt, H-P., Lahl, O., Born, J., & Wagner, U. (2008). Sleep loss

produces false memories. Plos One, 3, 1-9.


25

Durmer, J., & Dinges, D. (2005). Neurocognitive consequences of sleep. Seminars in

Neurology, 25(1), 117-129.

Euston, D. R., Gruber, A. J., & McNaughton, B. L. (2012). The role of medial prefrontal

cortex in memory and decision making. Neuron, 76, 1057-1070.

Frenda, S. J., Patihis, L., Loftus, E. F., Lewis, H. C., & Fenn, K. M. (2014). Sleep

deprivation and false memories. Psychological Science, 25(9), 1674-1681.

Fougnie, D. (2008). The relationship between attention and working memory. In N.

Johansen (Ed.). New research on short-term memory (pp. 1-45). Nova Science

Publishes, Inc.

Gais, S., & Born, J. (2004). Declarative memory consolidation: Mechanisms acting

during human sleep. Learning and Memory, 11(6), 679-685.

Garoff-Eaton, R., Slotnick, S., & Schacter, D. (2006). Not all false memories are created

equal: The neural basis of false recognition. Cerebral Cortex, 16, 1645-1652.

Gibbs, M. E., Hutchinson, D. S., & Summers, R. J. (2010). Noradrenaline release in the

locus coeruleus modulates memory formation and consolidation: Roles for α- and

β-adrenergic receptors. Neuroscience, 170, 1209-1222.

Horne, J. A. (1993). Human sleep, sleep loss and behavior: Implications for the prefrontal

cortex and psychiatric disorder. British Journal of Psychiatry, 162, 413-419.

Hunt, R., Smith, R., & Dunlap, K. (2011). How does distinctive processing reduce false

recall? Journal of Memory and Language, 65(4), 378-389.

Jenkins, J. G., & Dallenbach, K. M. (1924). Obliviscence during sleep and waking.

American Journal of Psychology, 35(4), 605-612.

Johns, M. (1991). A new method for measuring daytime sleepiness: The Epworth


26

Sleepiness Scale. Sleep, 14, 540-545.

Johns, M. (1992). Reliability and factor analysis of the Epworth Sleepiness Scale. Sleep,

15:4, 376-381.

Kim, Y., Elemenhorst, D., Weisshaupt, A., Wedekind, F., Kroll, T., McCarley, R.,

Strecker, R., & Bauer, A. (2015). Chronic sleep restriction includes long-lasting

changes in adenosine and noradrenaline receptor density in the rat brain. Journal

of Sleep Research, 4, 549-558.

Killgore, W. D. (2010). Effects of sleep deprivation on cognition. Progress in Brain

Research, 185, 105-129.

Kopelman, M. D. (1999). Varieties of false memory. Cognitive Neuropsychology, 16,

197-214.

Liu, Y., Wheaton, A. G., Chapman, D. P., Cunningham, T. J., Lu, H., Croft, J. B. (2016).

Prevalence of healthy sleep duration among adults. Morbidity and Mortality

Weekly Report, 65:6, 137-141.

McCabe, D., Presmanes, A., Robertson, C., & Smith, A. (2004). Item-specific processing

reduces false memories. Psychonomic Bulletin & Review, 11, 1074-1079.

McGaugh, J. L. (2000). Memory- A century of consolidation. Science, 287, 248-

251.

McGaugh, J. L., & Hertz, M. J. (1972). Memory consolidation. San Francisco: Albion.

Medina, J. (2009). Brain rules: 12 principles for surviving and thriving at work, home

and school. Seattle, WA: Pear Press.

Mercer, P., Merritt, S., & Cowell, J. (1998). Differences in reported sleep need among

adolescents. Journal of Adolescent Health, 23, 259-263.


27

Morgenthaler, T., Alessi, C., Friedman, L., Owens, J., Kapur, V., Boehlecke, B., &

Swick, T. (2007). Practice parameters for the use of actigraphy in the assessment

of sleep and sleep disorders: An update for 2007. Sleep, 30, 519-529.

Muzur, A., Pace-Schott, E. F., & Hobson, J. A. (2002). The prefrontal cortex in sleep.

Trends in Cognitive Sciences, 6, 475-481.

Okazaki, S. & Sue, Stanley. (1995). Methodological issues in assessment research with

ethnic minorities. Psychological Assessment, 7:3, 367-375.

Payne, J., Schacter, D., Propper, R., Huang, L., Wamsley, E., Tucker, M., Walker, M., &

Stickgold, R. (2009). The role of sleep in false memory formation. Neurobiology

of Learning and Memory, 92, 327-334.

Prokopová, I. (2010). [Noradrenaline and behavior]. Cesk Fysiol, 59, 51-58.

Prince, T., & Abel, T. (2013). The impact of sleep loss on hippocampal function.

Learning and Memory, 20, 558-569.

Roediger, H. L., & McDermott, K. B. (1995). Creating false memories: Remembering

words not presented in lists. Journal of Experimental Psychology: Learning,

Memory, and Cognition, 21, 803–814.

Schabus, M., Gruber, G., Parapatics, S., Sauter, C., Klösch, G., Anderer, P., &Zeithofer,

J. (2004). Sleep spindles and their significance for declarative memory consolidation.

Sleep, 27, 1479-1485.

Stadler, M., Roediger, H., & McDermott, K. (1999). Norms for word lists that create

false memories. Memory and Cognition, 27(3), 494-500.

Strine, T. W., & Chapman, D. P. (2005). Associations of frequent sleep insufficiency

with health-related quality of life and health behaviors. Sleep Medicine, 6, 23-27.


28

Thomsen, D. K., Mehlsen, M. Y., Christensen, S., & Zachariae, R. (2003). Rumination:

Relationship with negative mood and sleep quality. Personality and Individual

Differences, 34, 1293-1301.

Uematsu, A., Tan, B., & Johansen, J. (2015). Projection specificity in heterogeneous

locus coeruleus cell populations: Implications for learning and memory. Cold

Spring Harbor Laboratory Press, 22, 444-451.

Ullman, M. (2004). Contribution of memory circuits to language: The

declarative/procedural model. Cognition, 92, 231-270.

Van Dongen, H., Vitellaro, K., & Dinges, D. (2005). Individual differences in adult

human sleep and wakefulness: Leitmotif for a research agenda. Sleep, 28,

479-496.

Yamadori, A. (1971). Role of the spindles in the onset of sleep. Kobe Journal of Medical

Sciences, 17, 97-111.

Documents

The Effects of Distinctive Processing and Sleep Deprivation on False Memory