SCIENTIA
2006
The Journal of the Honors Program
About the Author
Mary Benn er is receiving a Bachelor of Science in Psychology with a minor in English.
Following graduation, Mary plans to pursue an occupation in her field of study to help her
narrow which program to pursue in graduate school. Mary plans to attend graduate school in
the fall of 2007 and eventually pursue a doctoral degree in mental health counseling. Mary
has presented research at the 2006 Eastern Psychological Association Conference. She is a
founding member and officer of the Peers On Wellness Peer Education group based out of the
Counseling/Student Development Center. Mary is also a member of Delta Epsilon Sigma and
Psi Chi National Honor Societies and Vice President of the Psychology Club. Mary elected to
pursue a Citation in Honors as an extra challenge to enhance her undergraduate learning
experience. Writing an honor’s thesis provided her with an opportunity to extend the
exciting implications of the research she conducted in her psychology courses. Mary would
like to especially thank her reader Christopher Moy for providing insights into her research
that she could not have gained elsewhere. Mary would also like to extend her gratitude to her
thesis director and research advisor, Dr. Crawley, for his endless encouragement and for
sharing his expertise throughout the process. Also, thanks are to be given to all members of
the Undergraduate Psychology faculty for sharing their wisdom and guidance and inspiring a
passion for psychology. Finally, Mary would like to thank her friends and family for their
direction and endless support when it was most needed.
5
Effects of Chewing Gum on Memory of Studied Words
Mary T. Benner
Abstract
The present study investigated the effects of gum chewing on cognitive performance and
memory. In experiment 1, participants completed a battery of cognitive tasks while chewing
sugared gum, sugar-free gum, or no gum (control group). Consistent with previous research,
chewing sugar-free gum led to increased performance on immediate word recall and visual
memory of studied material. Experiment 2 examined the effects of gum chewing during the
execution of serial-position recall tasks to investigate the effects of gum chewing on LTM and
STM. Forty-one students participated in a 2 (gum, no gum) x 2 (immediate recall, delayed
recall) between subjects comparison. Results indicate that chewing gum creates a significant
extension of the primacy effect among the first quarter of the serial position curve. This
evidence suggests that chewing gum during presentation and recall of a series of items improves
LTM.
Current trends in today’s society have created an obsession with improving memory and
a desire to ensure that memory remains effective despite aging. Considering the availability of
over-the-counter and herbal remedies, there are now many techniques that claim to effectively
enhance memory. Now more than ever, medical science has developed increasingly advanced
methods of improving natural human functions, including memory (Davidson & Conner, 2000).
However, improving some aspects of memory may not require such advanced medical
procedures and practices.
The experimental literature suggests that certain environmental factors possess the ability
to boost learning and memory capacity. For example, productive learning environments may be
created using certain lighting, wall colors, and scents. Cool and pale colors, such as mild blues
and greens, induce tranquil moods and have been used in educational institutions to create calm
spaces that are conducive to learning (Niedzwetzki, 1991; “Using Colors,” 1993). In addition to
focusing on the physical learning environment, some researchers have proposed that intellectual
ability can be improved by fragrances (e.g., McVeigh, 2004; Moss et al., 2003) or certain music
(i.e., the Mozart Effect).
For example, Shaw (Grandin, Shaw, & Peterson, 1998; Holden,
6
1999) and his colleagues have demonstrated that exposure to music, specifically Mozart,
increases spatial skills. Although there exists an abundance of research that has investigated the
effects of external stimuli on brain function, there are also chemical based catalysts that improve
cognitive performance.
Considering the relationship between food and cognition, Kanarek and Swinney (1990)
proposed that consumption of a calorie rich snack verses a low calorie snack would improve
cognitive performance on tasks involving sustained attention. Results of their study show that
consumption of a calorie rich snack significantly improved scores on backward digit span recall.
Compared to scores of the low calorie snack group, those in the calorie rich group also showed
improvements in arithmetic reasoning and attention. Thus, perhaps specific nutritional
components actually function to increase intellectual abilities.
Previous research has demonstrated that food can improve aspects of cognitive functions
after eating; however few studies have considered the possible effects on brain function during
eating. Using chewing gum as an independent variable, Wilkinson et al. (2002) proposed that
the act of chewing gum during cognitive tests would improve mental performance. Participants
were randomly assigned to free chewing, sham chewing, and quiet control groups, and cognitive
performance was assessed with the Cognitive Drug Research computerized battery. Results
revealed that participants in the free chewing group experienced a significant increase in
accuracy on immediate and delayed word recall as well as on spatial and numeric working
memory tasks. The results of the Wilkinson et al. (2002) study provide the first evidence that
gum chewing can, at least temporarily, improve intellectual functioning, but their conclusions are
limited by several factors and inspire an interesting research question. Specifically, perhaps it is
the act of mastication that improves certain cognitive functions and not caloric or nutritional
value.
Wilkinson et al. (2002) stated that the act of sham-chewing is unnatural and may have
taken concentration away from the CDR Tasks. Thus, sham-chewing may have led to a decrease
in performance relative to the free chewing condition. Second, Wilkinson et al. (2002) only used
sugar-free chewing gum in their study. In considering the findings of Kanarek and Swinney
(1990), the current study questioned whether chewing sugared gum that contains more calories
than sugar-free gum would even further enhance brain functioning. Furthermore, experiment 1
7
of the current study hoped a comparison of the effects of sugar-free and sugared gum might
provide insight into the notion that chewing alone increases functioning.
While Wilkinson et al. (2002) were unwaveringly certain that chewing gum improves
memory of studied objects, they were much less certain of the reasoning behind gum’s
effectiveness. Wilkinson et al. (2002) speculated that gum improves memory because the act of
mastication improves blood flow in regions of the brain that are known to mediate memory
functioning (Sesay, Tanaka, Ueno, Lecaroz, & De Beaufort, 2000). However, the results of their
own experiment suggest this is not a possible explanation. Participants in the sham-chewing
group of the Wilkinson et al. (2002) study did not experience the same increase of memory, as
did participants in the free-chewing condition.
Wilkinson et al. (2002) also speculated that their results reflected the ability of glucose to
cause a stimulant arousal that improved participant alertness, consequently improving memory.
Stephens and Tunney (2004) replicated the work of Wilkinson et al. (2002) and incorporated an
experimental design to investigate the role of glucose on memory. In a 2 x 2 between subjects
design, participants in the experimental group were administered 25 g of glucose powder
dissolved into 250 ml of water. Participants in the control group drank 250 ml of plain water.
The second condition of the experiment was chewing gum verses sucking on a sugar-free mint.
Participants in each of the four groups completed a battery of eight neuropsychological tests with
tasks similar to those in the CDR used by Wilkinson et al. (2002). Results of the Stephens and
Tunney (2004) study well replicated those of Wilkinson et al. (2002). Specifically, Stephens and
Tunney (2004) discovered that chewing gum enhanced episodic long-term memory and working
memory, and that in terms of delayed recall, the “enhancement due to chewing gum was not
paralleled by glucose enhancement.” In considering their results, Stephens and Tunney (2004)
suggest that there must be another mechanism that more completely explains gum’s
effectiveness.
A second replication of the Wilkinson et al. (2002) study argued that gum’s effectiveness
on memory is related to context dependent effects (Baker, Bezance, Zellaby, & Aggleton, 2004).
Research has shown that there is a benefit in learning or rehearsing material in a similar, or in the
exact environment where the recall testing is administered (Golden & Baddeley, 1975; Tulving
& Thompson, 1973). Since an improvement in memory of studied words was one of the main
findings of Wilkinson et al. (2002), Baker et al. (2004) focused specifically on memory of a list
8
of fifteen studied words. Baker el al. tested the context dependency of gum chewing using a 2 x
2 between subjects design that included chewing or no chewing during the presentation of a
word list and during recall. Each subject of the four groups was tested for recall accuracy in
immediate and twenty-four hour delay conditions. While, revealing an effect of gum chewing,
the results provided mixed support for the context-dependency hypothesis.
The results of the Baker et al. (2004) study revealed that, in both immediate and twentyfour hour delayed recall, participants who chewed gum during word presentation and recall
remembered significantly more words than participants in the other three groups. In contrast,
with the context dependency hypothesis, the group that did not chew gum at either phase of the
study performed poorer than both groups that chewed gum during one phase. Results of the
twenty-four hour delayed recall support the context dependency hypothesis. Participants in the
consistent chewing or non-chewing groups both recalled more words than those in inconsistent
chewing groups. Thus, although the results of the Baker et al. (2004) study showed evidence
that chewing gum during both presentation and recall of words increased memory, their results
do not reliably suggest that this phenomenon occurs because of context effects. That is, if gum’s
effects were purely context dependent, one would expect that the gum-gum and no gum-no gum
groups would have increased memory over inconsistent chewing in both immediate and delayed
recall.
The results of Baker et al. (2004) indicate a further possible explanation of gum’s
effectiveness on memory. In particular, although participants in the gum-gum group recalled
significantly more words than participants in the other three groups, recall improved by only
three words more than participants of the other groups during the immediate recall. Recall
results were much more distinctive in the twenty-four hour delayed recall, in which participants
in the gum-gum group recalled up to five more words than participants in other groups. Since
immediate and delayed recalls reflect the operations of short-term and long-term memory
respectively, gum’s effect on memory may be more strongly related to long-term memory
processes rather that short-term memory processes.
Generally, information must be made specific and distinctive from the rest of the material
presented to the human mind for that information to be transferred from short-term memory to
long-term memory. Thus, perhaps chewing gum while studying a group of presented objects
allows those objects to become distinctive, transferring them to long-term memory and
9
increasing the ability to remember them. To test this hypothesis the current study employed a
serial position recall as a technique to provide greater insight into memory processes than the
free recall tasks used in previous experiments investigating gum chewing. In the second
experiment, the effects of chewing gum during the execution of serial-position recall tests were
investigated to understand the effects of gum chewing on short-term and long-term processes of
memory.
Unlike ordinary free recall, serial position recall measures both short-term and long-term
memory through primacy and recency effects (Bjork & Whitten, 1974). Recency effects occur
when an individual is able to recall the most recent items presented, or the items at the end of the
list, from their short-term memory. Primacy effects draw on information from long-term
memory for items presented at the beginning of list, items for which there exists more time to
rehearse or employ mnemonic devices. Serial position recall also reveals information about the
encoding of information, which is the process of transferring information from short-term to
long-term memory, and about retrieval, the accessing of information from long-term memory.
Consequently, employing gum chewing to the task of a serial position recall will hopefully
uncover how gum affects the encoding and retrieval processes of memory.
Experiment 1
Method
Participants
Twenty-seven undergraduate psychology students at Marywood University participated in partial
fulfillment of a course requirement. Data for the five participants in the quiet control, no chewing
group was obtained from archival research. Demographically, the participant group consisted of
twenty-one females and six males. Participant ages varied between 18 and 44, with an average
age of twenty-three.
Design and Procedure
The design of the proposed study included a between subjects comparison with one
independent variable with three levels, sugar-free gum chewing, sugared gum chewing, and no
chewing. Participants volunteered by filling out sign-up sheets on the research bulletin board.
Upon entering the designated room, participants were randomly assigned to one of the two
10
experimental groups. After reading all instructions and completing the consent form,
participants were given either a piece of sugared or sugar-free gum and were instructed to being
chewing the gum. Participants received no indication as to what type of gum they were given.
Directly following the initiation of chewing, participants began the computerized battery, which
was modeled on the CDR. The gum was chewed constantly throughout the experiment. After
completing the cognitive tasks, participants were debriefed and instructed to not share
information about the study with anyone else.
Apparatus
Participants completed the cognitive battery on a computer, and the tasks were presented
on a color monitor. Participants responded by using the computer mouse, writing down words
on paper, for the two word recall tasks, and by pressing the right and left arrow keys on a
keyboard to indicate yes and no answers for all other tasks.
Testing Instruments
As described in Table 1, eight different tasks were included in the cognitive battery that
measured accuracy, latency, and/or reaction time.
Results
Statistical results were evaluated at the .05 level and obtained by performing a one-way analysis
of variance (ANOVA) with post hoc test to isolate between-group effects for each task.
Statistical analysis of participant data as shown in Figure 1 revealed that the chewing of sugarfree gum, as compared to sugared gum, increases performance on delayed word recall and
significantly improves immediate word recall, t(20) = 2.29, p < .05. Also, as an inspection of the
means in Figure 2 show, chewing sugar-free gum significantly improves visual memory for
studied images over sugared gum chewing and no chewing, F (2, 24) = 12.0, p < .05.
Experiment II
Method
Participants
Data for the current experiment was drawn from forty-one undergraduate psychology students at
Marywood University. Demographically, the participant group consisted of thirty-four females
11
and seven males with a mean participant age of 20.3 years. Participants partook in the study on a
volunteer basis, yet most participants received credit towards a course requirement or earned
extra credit.
Design and Procedure
The design of the current study is a 2 (gum, no gum) x 2 (immediate recall, delayed
recall) between subjects comparison. Participants volunteered by filling out sign-up sheets on
the research bulletin board. Upon entering the designated room, participants were randomly
assigned to one of the four groups, no gum – no delay, no gum – delay, gum – no delay, and gum
– delay.
After receiving all instructions and completing the consent form, participants in the
experimental groups received a piece of sugar-free gum. Participants who may have had
concerns about chewing gum or questions about the nutritional content of the gum being used in
the study were encouraged to discuss their questions with the experimenter. It was stressed that
the participant was not required to continue with the experiment if they rather not chew the gum
used in the study.
Participants randomly assigned to a gum-chewing group began chewing prior to
beginning a memory task that included the presentation of to-be-remembered words on a
computer screen. Participants studied four lists of twenty words with a presentation rate of one
second. Words were randomly generated using a computer program. All words were four letter
nouns with regulated Kucera-Francis frequencies (Francis & Kuera, 1982). The mean KuceraFrancis frequency was 21.45 for each of the four lists. Following the presentation of each list,
participants wrote down each remembered word in either an immediate or two-minute delayed
free recall. Participants in the gum conditions chewed a stick of Wrigley’s sugar- free Extra
spearmint gum (Wm. Wrigley Jr. Company, Chicago IL) constantly throughout the experiment.
Participants in the delayed condition completed the Rogers Indicator of Multiple
Intelligences (RIMI; Rogers, 1995; as cited in Corey & Schneider-Corey, 2006) during the two
minutes delays between each list. Participants in no delay conditions completed the self-report
measure following completion of the word tasks. After completing the memory tasks and the
RIMI, participants were debriefed and then cautioned not to share information about the study
with potential participants.
12
Results
Statistical results were evaluated at the .05 level and obtained by performing a 2 x 2
analysis of variance (ANOVA) with post hoc tests to isolate between-group effects. In order to
control for a nuisance variable effect of poor memory, results were filtered for participants
possessing at least fifteen percent memory accuracy. Multivariate tests yielded a significant
interactions of position by delay, F(3, 37) = 5. 95, p < .05, and position by gum by delay, F(3,37)
= 3.00.
The current study followed the statistical methodology of Brooks (1999) who collapsed
points of the serial position curve into sequential segments to more readily compare sets of
positions within the curve to isolate primacy and recency effects. The serial position curve was
divided into sets of positions 1 – 5, 6 – 10, 11 – 15, and 16 – 20. Independent samples tests
revealed a significant increase in accuracy across the first five items of the curve for participants
chewing gum during the delayed condition of the experiment, t(19) = -3.39, p < .05. As seen in
Figure 3, the mean accuracy of these first items for the gum chewing group was 44.5% and only
28.6% for no chewing participants. A comparison between Figure 3, accuracy at delayed recall
and Figure 4, accuracy at immediate recall, provides for a more comprehensive conception of
gum’s effects on short-term verses long-term memory.
Between group effects of learning style as measured by the RIMI (Rogers, 1995; as cited
in Corey & Schneider-Corey, 2006) were also analyzed to detect whether learning style played a
function in memory accuracy during this particular experiment, or if gum-chewing was the sole
mediating factor. Data analysis revealed no significant effects of learning style as an influence
of memory accuracy.
Discussion
The findings of the current study replicate the results of previous work, and supplement
the reliability of the hypothesis that chewing gum does exert a certain enhancing power on
memory. The results of experiment 1 illustrate that the chewing of sugar-free gum selectively
improves measures of immediate and delayed memory. The first experiment of the present study
combined results of two previous research experiments and attempted to find results supporting
the composite of both studies’ implications. Results were consistent with the work of
Wilkinson et al. (2002), as it was determined that chewing sugar-free gum improved aspects of
verbal and visual memory. Yet, in the attempt to replicate findings by Kanarek and Swinney
13
(1990) the current study was unsuccessful. Kanarek and Swinney (1990) proposed that foods of
higher calorie content improve functioning verses foods of lower calorie content. The results of
the present work instead revealed that sugar-free gum, consisting of five calories per serving,
improved functioning over sugared gum, which consists of ten calories per serving. Such results
may have several implications.
Particularly, it should be noted that in terms of sugar content, while the sugared gum used
in the current study contained two grams of sugar, the sugar-free gum contained two grams of a
substance known as sugar alcohols. Nutritional information posted by the Yale-New Haven
Hospital (“Eat any,” 2005) reports that sugar alcohols are used as a sweetening agent in foods.
Sugar alcohols contain half the calories of ordinary sugar because they are converted to glucose
more slowly and need little or no insulin to be metabolized by the body (“Eat any,” 2005).
Considering that the glucose in sugar alcohols metabolizes more slowly, perhaps this extends
chewing gum effects throughout the entire chewing episode, rather than the glucose being
metabolized within the first few minutes of gum chewing. The results of the current study may
have failed to develop findings synonymous with the work of Kanarek and Swinney (1990) due
to the rather minor variance in caloric content between the two gums, and also due to differences
that exist in the physiological processing of the different forms of sugar. Therefore, it is
suggested that further research aimed at investigating the effects of sugar or caloric content on
cognition should consider the usage of other foods that would possess a greater contrast between
the sugared version and its sugar-free substitute.
Rather than altering the stimuli used in such experiments, it may prove beneficial to
instead incorporate different testing mechanisms. Cognitive batteries such as the CDR provide
measures on a range of cognitive abilities; however experiment results thus far have posited that
chewing gum produces effects in memory related tasks. Thus, the structure of the second
experiment focused solely on memory in terms of immediate and delayed recall to allow for a
further understanding of the effects of gum chewing.
The results of the second experiment provide insight into the psychological mechanics of
gum’s ability to increase memory functioning. Consistent with the appearance of a superior
effect of gum chewing at delay in the Baker et al. (2004) study, the present study found that gum
specifically enhances the power of memory in a delayed recall condition. The existence of a
significant increase in memory accuracy for the first five items of the serial position curve
14
indicates a strong primacy effect, which equates with the properties of long-term memory. Thus,
chewing gum while studying provides for a stronger long-term memory of the first few studied
items, demonstrating that gum improves the encoding of information into long-term memory.
The lack of a significant interaction between learning style and memory performance
suggest that chewing gum alone improves memory regardless of one’s adeptness at completing
such tasks. It may be argued that participants who relate well to and learn best from reading,
such as those of the verbal-linguistic learning style, would have displayed an advanced
performance compared to other participants (RIMI; Rogers, 1995; as cited in Corey &
Schneider-Corey, 2006). Learning styles could have caused a possible extraneous variable in the
design of the present experiment. However, since no significant effects of learning style were
observed, it can be assumed that chewing gum improves memory regardless of learning style.
These results may have a powerful implication for those individuals who struggle with
memory. For instance, some students who are bodily-kinesthetic learners must usually
experience things hands on in order to learn them and may often have difficulty remembering
written or spoken material (RIMI; Rogers, 1995; as cited in Corey & Schneider-Corey, 2006).
However, if students experiencing such difficulty would employ gum chewing to their regular
studying routine, they may experience surprising benefits, as outlined by the results of this study.
Further replication of this research is necessary to test the reliability of the finding. In addition,
collecting data from real life attempts to use this theory to increase memory on academic tasks in
scholastic settings would add to the understanding of gum’s effect on memory.
Previous research and future research questions in the proposed area seem to be
abundant. In general, it appears that many forms of stimuli, from the stimulant effects of wall
color to the physiological effects of food, may be responsible for enhancing one’s level of
cognitive performance. Conducting such research allows for an understanding of the types of
stimuli that effect areas of the brain involved in the performance of cognitive tasks. As the
human brain is viewed as being thoroughly complex, it becomes somewhat of an appreciation to
learn that the slightest and simplest of stimuli, such as chewing gum, can create such positive
effects on memory functioning.
Something within the simple construct of chewing gum has enhanced memory
functioning. Chewing gum certainly is not an innovation of medical science, nor does it give the
impression of being a medical miracle, however, empirical research has reliably shown that
15
chewing gum improves certain aspects of memory (Wilkinson, Scholey, & Wesnes, 2002;
Zoladz & Raudenbush, 2005). Though there is currently ample support for the concept that gum
improves memory, it is necessary to continue research on gum and memory to pinpoint what
aspects of the brain gum effects and what the applications of such research are for the general
public.
16
References
Baker, J. R., Bezance, J. B., Zellaby, E., & Aggelton, J. P. (2004). Chewing gum can produce
context-dependent effects upon memory. Appetite, 43(2), 207-210.
Bjork, R. A., & Whitten, W. B. (1974). Recency-sensitivity retrieval in long-term free recall.
Cognitive Psychology 6, 173-189.
Brooks, B. M. (1999). Primacy and recency in primed free association and associative cued
recall. Psychonomic Bulletin & Review, 6(3), 479-485.
Corey, G., & Schnieder-Corey, M. (2006). I never knew I had a choice (8th ed.). Belmont, CA:
Thompson Brooks/Cole.
Cognitive Drug Research, Ltd. (1986). Cognitive Drug Research. Retrieved November 5, 2004,
from http://www.cdr.org.uk
Davidson, J. R., & Conner K. M. (2000). Herbs for the mind: what science tells us about
nature’s remedies for depression, stress, memory loss, and insomnia. New York: NY:
Guilford Press.
Eat any sugar alcohol lately? (2005). Yale-New Haven Hospital Nutrition Advisor. Retrieved
April 28, 2005, from http://www.ynhh.org/online/nutrition/advisor/sugar_alcohol.html
Francis, W. N., & Kuera, H. (1982). Lexicon and grammar. Frequency analysis of English
usage. Boston, MA: Houghton Mifflin.
Golden, D. R., & Baddelely, A. D. (1975). Context-dependent memory in two natural
environments: on land and under water. British Journal of Psychology, 66, 99-104.
Grandin, T., Shaw, G. L., & Peterson, M. (1998). Spatial-temporal versus language-analytic
reasoning: the role of music training. Arts Education Policy Review, 99(6), 11-14.
Holden, C. (1999). Music as brain builder. Science, 283(5410), 2007.
Kanarek, R. B., & Swinney D. (1990). Effects of food snacks on cognitive performance in male
college students. Appetite, 14(1), 15-27.
McVeigh, G. (2004). Instant smarts. Prevention, 56(10), 84.
17
Moss, M., Cook, J., Wesnes, K., & Duckett, P. (2003). Aromas of rosemary and lavender
essential oils affect cognition and mood in healthy adults. International Journal of
Neuroscience, 113(1), 15-38.
Niedzwetzki, J. (1991). Colour and lighting in public libraries. APLIS, 4(2), 103-105.
Scholey, A. (2004a). Further issues regarding the possible modulation of cognitive function by
the chewing of gum: response to Stephens and Tunney (2004) and Tucha et al. (2004).
Appetite 43(2), 221-223.
Scholey, A. (2004b). Chewing gum and cognitive performance: a case of a functional food with
function but no food? Appetite 43(2), 215-216.
Sesay, M., Tanaka, A., Ueno, Y., Lecaroz, P. & De Beaufort, D. G. (2000). Assessment of
regional cerebral blood flow by xenon-enhanced computed tomography during
mastication in humans. Kelo Journal of Medicine 49(1), A125-28.
Stephens, R., & Tunney, R. J. (2004). Role of glucose in chewing gum-related facilitation of
cognitive function. Appetite, 43(2), 211-213.
Tulving, E., & Thompson, D. M. (1973). Encoding specificity and retrieval processes in
episodic memory. Psychological Review, 80, 352-373.
Tucha, O., Mecklinger, L., Maier, K., Hammerl, M., & Lange, K. W. (2004). Chewing gum
differentially affects aspects of attention in healthy subjects. Appetite, 42(3), 327-329.
Using color to create high impact business presentations. (1993). American Demographics,
15(9), 18-19.
Wilkinson, L., Scholey, A., & Wesnes, K. (2002). Chewing gum selectively improves aspects of
memory in healthy volunteers. Appetite, 38(3), 235-236.
Zoladz, P. R., & Raudenbush, B. (2005). Cognitive enhancement through stimulation of the
chemical senses. North American Journal of Psychology, 7(1), 125-140.
18
Task
Word Presentation- Immediate
and Delayed Recall
Measures
Accuracy
Picture Presentation and
Recognition
Accuracy and
Latency
Simple Reaction Time
Latency
Digit Vigilance
Spatial Working Memory
Numeric Working Memory
Latency
Accuracy and
Latency
Accuracy and
Latency
Description
Ten words appear one at a time, and
participants are asked to write down
as many as they can remember in
immediate and delayed recall within a
60 second time span.
20 pictures are presented one at a
time, and then are shown again later
in a series that also contains new
images. Participants must decide
which pictures were presented in the
original set.
Each time the word “yes” appears on
the screen, participants respond by
striking the corresponding ‘yes’ key
on the keyboard.
A series of changing numbers is
presented one at a time in the center
of the screen, and a target number is
shown to the right. The participant is
instructed to strike the corresponding
correct key when the number in the
center matches the target number.
An image of a house with nine
windows appears on the screen with
target windows lit. In viewing the
preceding houses, participants must
decide if the same window was or
was not lit in the target example.
Participants are asked to study a set
of five target numbers. Then, a series
of changing numbers is presented and
participants must strike the
corresponding correct key when one
of the five studied numbers appears.
Table 1. Computerized battery task descriptions and type of dependent variable measurements
for each task.
19
8
7
Accuracy
6
5
4
3
2
1
0
Sugar-free
Sugared
Condition
Figure 1. Immediate word recall scores for sugar-free and sugared gum chewing groups.
20
1
0.9
0.8
Accuracy
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Control
Sugar-free
Sugared
Condition
Figure 2. Visual memory scores for studied images for no chewing, quiet control, sugar-free,
and sugared gum chewing groups.
21
Delayed Recall
0.5
0.45
Proportion Correct
0.4
0.35
Gum
No Gum
0.3
0.25
0.2
0.15
p1to5
p6to10
p11to15
p16to20
Serial Position
Figure 3. Proportion correct of chewing and no chewing groups during delayed recall condition.
22
Immediate Recall
0.5
Proportion Correct
0.45
0.4
No Gum
Gum
0.35
0.3
0.25
0.2
p1to5
p6to10
p11to15
p16to20
Serial Position
Figure 4. Proportion correct between chewing and no chewing groups during immediate recall
condition.