Neuroscience & Medicine, 2012, 3, 243-250
http://dx.doi.org/10.4236/nm.2012.33028 Published Online September 2012 (http://www.SciRP.org/journal/nm) 243
Gum Chewing and Cognition: An Overview
Lara Tucha, Janneke Koerts
Department of Clinical and Developmental Neuropsychology, University of Groningen, Groningen, The Netherlands.
Received June 26th, 2012; revised July 30th, 2012; accepted August 5th, 2012
ABSTRACT
In recent years, there was a debate ab out the effects of gum chewing on v arious aspects of cogn itive functio ning. In th is
review, the results of previous studies are presented and summarized. There is a clear indication that gum chewing can
improve various aspects of cognitive function ing including memory, attention and both executive and intellectual func-
tioning. However, there is also clear evidence that chewing gum during cognitive tasks can adversely affect task per-
formance. Therefore, it can be concluded that the replication of (beneficial or detrimental) effects of gum chewing on
cognition has been proven to be very difficult. Consequently, the robustness of reported effects of gum chewing on
cognition has to be questioned. Suggestions for future research are given.
Keywords: Gum Chewing; Mastication; Cognition; Memory; Review
1. Introduction
In recent years, there was a debate about the effects of
gum chewing on cognition. A number of well controlled
studies examined the effects of chewing gum on aspects
of memory and attention in healthy young adults and
found that gum chewing enhances cognitive functioning,
in particular with regard to learning and memory. Be-
cause of these positive findings, there was quite some
enthusiasm among researchers concerning this beneficial
impact of gum chewing on cognition. For example,
Scholey [1] summarized in a brief review that “Recent
reports suggest that enhancement of memory perform-
ance while chewing gum is a fairly robust phenomenon”
(p. 215). Furthermore, an increase of learning perform-
ance of at least 30% was claimed following gum chewing
(Lehrl, as cited in [2]). This enthusiasm might also ex-
plain why some researchers interpret non-significant re-
sults of a pilot study as an indication of a facilitating ef-
fect of gum chewing [3] which had to be rectified fol-
lowing completion of a full-scale study published two
years later by the same group [4]. It has been assumed
that the cognition enhancing effect of gum chewing is
caused by an increased release of insulin and a changed
pattern of regional cerebral blood flow, in particular in
fronto-temporal regions of the brain [5-7]. These as-
sumptions are consistent with the findings of neuroi-
maging studies showing that gum chewing resulted in
bilateral increases of neuronal activity in the sensorimo-
tor cortex, supplementary motor area, prefrontal cortex,
insula, thalamus, and cerebellum [8].
The reports of a performance-enhancing effect of gum
chewing attracted the attention of media worldw id e. Both
national and international media covered these findings
in the context of facilitation of children’s learning at
school and the ban of chewing gum in schools. In fact, if
gum chewing really helps memorizing and remembering
information as well as increasing the ab ility to pay atten-
tion, one would conclude that gum chewing should not
only be allowed during classes but also that chewing gum
is strategically used in classes, e.g. in situ ations in which
new and complex material is taught or during exams. An
internet search using the terms “school” and “chewing
gum” reveals that teachers, principals and school authori-
ties are indeed confronted with this discussion.
However, there is also a considerable number of recent
studies that failed to replicate the beneficial effects of
gum chewing on cognition. Moreover, an increasing
number of studies even demonstrated negative effects of
gum chewing on cognition. On this background, it ap-
pears reasonable to review the literature to get a clearer
understanding of the effects of gum chewing on cogni-
tive task performance.
2. Method
To identify relevant literature, searches of Medline and
Web of Knowledge were conducted by using the key-
word “chewing gum” individually combined with the
search terms “cognition”, “memory”, “learning”, “atten-
tion”, “spatial” and “executive functions”. Furthermore,
references from articles and books were searched for
additional references. Studies using chewing gum in
combination with pharmacological agents (e.g. nicotine)

Gum Chewing and Cognition: An Overview
244
were excluded. Furthermore, only the results of stan-
dardized cognitive assessments were considered. Results
of questionnaires or any other measures of self-evalua-
tion were not included. Studies focusing on the effect of
gum chewing on stress were also excluded. Finally, re-
views with no original data, and animal studies were ex-
cluded. In total, 26 relevant references were identified
and included in the present review.
3. Effects of Gum Chewing on Cognition
3.1. Immediate and Delayed Memory
The terms immediate and delayed recall of information
refer to the reproduction of previously learned informa-
tion at a given period of time. While “immediate recall”
usually indicates the reproduction of information imme-
diately after a defined learning period, “delayed recall”
refers to the reproduction of information after a pro-
longed period of time following learning (several min-
utes to days or even longer).
Word recall. In one of the first studies examining the
effects of gum chewing on cognition, Wilkinson and
colleagues [5] found that the chewing of a piece of
sugar-free chewing gum resulted in a significant im-
provement of both the immediate and delayed recall of
previously learned words (delayed recall after less than
an hour; word list used: 15 words, visual presentation,
one learning trial). These findings were confirmed by
Stephens and Tunney [9] in a study focusing on the role
of glucose in the effects of gum chewing. These authors
used a word list containing 15 words which were pre-
sented auditorily over five trials to participants (delayed
recall after less than an hour). Baker and colleagues [10]
could only partially replicate these findings (word list
used: 15 words, visual presentation, one learning trial).
While these author s found no effects on immediate recall,
beneficial effects of gum chewing on delayed word recall
were observed. It is notably that the assessment of de-
layed word recall in this study was performed after a
delay of 24 hours. This might indicate that retrieval of
previously learned information is significantly increased
for a prolonged period of time when gum was chewed
during learning (and possibly also during recall, please
see discussion of context-dependent effects below). Tu-
cha and colleagues [6] performed two experiments to
assess the effect of gum chewing on attentional func-
tioning and immediate and delayed word recall (delayed
recall after less than an hour; word list used: 15 words,
auditory presentation, one learning trial). Data analysis
failed to find any facilitating effect of gum chewing on
immediate and delayed recall. Miles and Johnson [11]
performed two well controlled experiments and also
failed to find a facilitative benefit of gum chewing on
immediate and delayed word recall (delayed recall after
24 hours; word list used: 15 words, visual presentation,
two learning trials). In another experiment the same au-
thors [12] found that chewing gum during learning did
not improve subsequent recall (delayed recall after 24
hours; word list used: 15 words, visual presentation, one
learning trial), however their data provided some evi-
dence that gum chewing during learning or at recall
might improve delayed recall. In another study of the
same group [13] even detrimental effects of gum chew-
ing on immediate and delayed recall were observed (de-
layed recall after 24 hours; word list used: 15 words,
visual presentation, one learning trial). In accordance
with these findings, Smith [14] also found negative ef-
fects of gum chewing on recall (delayed recall after less
than an hour; word list used: 15 words, visual presenta-
tion, one learning trial). In this study, gum chewing re-
duced both immediate recall and recognition of the pre-
viously learned words. In this context, it is remarkable
that a previous study [15] in which the same test was
used revealed no indications of any effects of gum
chewing. Miles, Charig and Eva [7] applied an immedi-
ate recall paradigm in order to assess the effect of gum
chewing on long-term memory (word lists used: 15
words, visual presentation, one learning trial). In their
paradigm, the authors prevented the participants to
maintain recently presented information (words of a
word list) within their short-term memory by articulatory
suppression (counting b ackwards after initial learning fo r
a period of 30 seconds). Similar to the previous studies,
this experiment failed to find beneficial effects of gum
chewing on learning or retrieval of previously learned
information. In contrast, Onyper and colleagues [16] re-
ported a positive effect of gum chewing on delayed
memory (delayed recall after 3 minutes; task applied
under 2 conditions, i.e. with full or divided attention;
word lists used: 30 wo rds, visual presentation , one learn-
ing trial per condition) but only if participants chewed
gum prior to the assessment (experiments 1a and 1b) and
not during the assessment (experiment 2). Furthermore,
the effect was only observed if the assessments of mem-
ory were performed early in the testing session.
Other measures of immediate and delayed recall of
information. Wada and colleagues [17] did not find any
effect of gum chewing on shor t-term memory as assessed
by a computerized short-term memory task requiring
participants to memorize random eight-digit numbers.
However, detrimental effects of gum chewing were re-
ported by Kozlov and colleagues [18] who performed a
series of well-controlled studies demonstrating that
chewing gum impairs immediate recall. By modifying
various variables within their experiments, the authors
could on the one hand replicate their findings and on the
other hand show that the detrimental effect of gum
chewing was independent of the material used in the as-

Gum Chewing and Cognition: An Overview 245
sessment (letters or numbers; item sequence or item
identity) as well as of the modality of presentation (visual
or auditory). Moreover, Kozlov and colleagues [18] re-
vealed that the adverse effects of gum chewing on
short-term memory are similar to the detrimental effects
of finger tapping. With regard to the delayed recall of
information, Wilkinson and colleagues [5] found no ef-
fects of gum chewing on performance in a delayed pic-
ture recognition task (recall after less than an hour; 20
photographic images, visual presentation, one learning
trial). Allen and colleagues [4] asked first-year incoming
dental students to listen to a videotaped lecture about
dental anatomy (50 minutes) and to complete afterwards
a multiple choice test about the lecture. Following this
assessment, students were asked to read a reading com-
prehension passage (20 minutes) and to complete a mul-
tiple choice test about this text. While the former test
represented a measure of specific learning, the latter test
was used as a measure of general learning. Despite the
fact that the study was well designed and controlled for
various variables (e.g. compliance with instructions), the
authors failed to find any memorial facilitation of chew-
ing gum. In a study on 4th and 5th grade students of ele-
mentary schools, positive effects of gum chewing were
found on a story comprehension test [19]. Children were
asked to listen to short stories and to memorize as much
of these stories as possible. After 5 minutes and 24 hours,
children were requested to write down as much as they
could remember from these stories. Data analysis re-
vealed that there was no effect of gum chewing on the
performance at the 24 hours delayed recall trial. In the 5
minutes delayed recall trial however, children who
chewed gum during learning and recall performed sig-
nificantly better than children without gum at learning,
children without gum at recall and children without gum
at learning and recall. Smith [20] used short stories in his
study and asked participants to recall the stories twice:
less than one hour after learning and after a period of two
days. There was no effect of gum chewing on recall per-
formance.
Summary of studies examining the effect of gum chew-
ing on memory. In total, 16 studies examined the impact
of gum chewing on aspects of immediate and delayed
recall. Two studies found beneficial effects of gum
chewing on immediate recall of information [5,9] and six
studies reported facilitating effects of gum chewing on
delayed recall of information [5,9,10,12,16,19]. In con-
trast, one study reported detrimental effects of gum
chewing on immediate and delayed recall [13] and two
studies on immediate recall only [14,18]. Two studies
failed to find an y effects of gum chewing on both imme-
diate and delayed recall [6,11]. In addition, four studies
found no evidence of facilitating or detrimental effect of
chewing gum on immediate recall [10,12,15,17] and four
studies failed to find effects on delayed recall [4,7,19,
20].
3.2. Context-Dependent Effects of Gum Chewing
on Memory
Scholey [21] speculated that Tucha and colleagues [6]
failed in their attempt to replicate a facilitating effect of
gum chewing on memory because of a shift in context.
The term context refers to the impact the environment or
internal state of an individual has on information acquisi-
tion and retrieval. In general, it was shown that the recall
of information is superior when the context during recall
resembles the context of learning than when learning and
retrieval of information is performed in different contexts
[22,23]. In their experiments, Tucha and colleagues [6]
asked participants to chew the same piece of chewing
gum throughout the whole test session. Therefore, the
assumption that some properties of the chewing gum
might have changed throughout the test period appears
quite reasonable (e.g. consisten cy, texture or flavor of the
gum). On the basis of Scholey’s [21] assumption, six
studies examined whether chewing gum can produce
context-dependent effects upon memory functioning. The
typical design of these studies was that participants
learned word lists (see above) either whilst chewing gum
or not chewing gum and that they were requested to re-
call the words in the same or alternate context. Bak er and
colleagues [10] were the first to examine context-de-
pendent memory effects of gum chewing. These authors
performed two experiments and found that gum chewing
can induce context-dependent effects on delayed recall
(24 hour d elay). A ch ange of co ntext during learning and
retrieval appeared to produce adverse effects on recall.
Furthermore, these authors found that sucking a piece of
chewing gum can also result in context-dependent mem-
ory effects. Johnson and Miles [11-13] performed several
experiments on this topic but could not find a con-
text-dependent benefit on delayed recall when partici-
pants were asked to chew gum during learning and re-
trieval of information. It appears important to point out
that these authors could even not find context-dependent
memory effects despite attempts of close replication of
the study of Baker and colleagues [10]. In one study,
Johnson and Miles [13] even report superior performance
of those participants who did not chew gum during both
learning and recall. However, in another study Miles and
colleagues [7] performed an immediate recall paradigm
including articulatory suppression (see above) and ob-
served a context-dependent memory effect of gum chew-
ing. Nevertheless, participants who chewed gum during
both learning and recall did not perform better in the
memory task than participants who did not chew gum
during learning and recall. Overman and colleagues [24]
asked participants to either chew a piece of cinnamon

Gum Chewing and Cognition: An Overview
246
gum or to suck a sweet with cinnamon flavor during
learning and recall. These authors also failed to find any
indication of context-dependent memory effects of gum
chewing (recall after less than an hour; word list used:
two word lists containing 15 words each (concrete versus
abstract words), visual presentation, one learning trial).
Summary of studies examining context-dependent ef-
fects of gum chewing on memory. Two studies observed
that chewing gum can pr ovoke context-dependent effects
on long-term memory [7,10]. However, four studies
failed to replicate context-dependent effects of gum
chewing upon memory [11-13,24]. In this context, it ap-
pears to be important to emphasize that context-depen-
dent effects of chewing gum on memory did not neces-
sarily mean that memory performance was better when
participants chewed gum whilst leaning and recalling
information in comparison to their p erformance wh en n ot
chewing gum. Reports of context-dependent memory
effects indicate that participants in the consistent condi-
tions which are the con ditions in which both learning an d
recall was performed in the same context (both with gum
or both without gum) performed better than participants
in the inconsistent context conditions (gum during learn-
ing and no gum during recall or vice versa).
3.3. Attention
Attention is a critical ability that is important for a vari-
ety of functions of everyday life including perceptual,
motor, emotional and cognitive functioning. Since the
quantity of information that can be processed simultane-
ously is limited, the attention system directs behaviour
according to temporal and spatial characteristics or situ-
ational requirements [25]. Current models and theories of
attention define attention as a multidimensional concept
with several distinct components or functions [26-30].
Although different models of attention were proposed,
the similarities among them are more striking than the
differences between them. Van Zomeren and Brouwer
[30] integrated the main characteristics and requirements
of various models and devised a multid imensional model
of attention which contains the following components:
alertness, subdivided into tonic and phasic alertness,
vigilance/sustained attention, selective attention, divided
attention and strategy/shifting. While tonic alertness re-
fers to a relatively stable level of attention wh ich ch ang es
slowly according to diurnal physiological variations of
the organism, phasic alertness is the ability to enhance
the activation level following a stimulus o f high priority.
The ability to sustain attention enables a subj ect to direct
attention to one or more sources of information over a
relatively long and unbroken period of time. Vigilance,
as a special type of sustained attention, is the ability to
maintain attention over a prolonged period of time during
which infrequent response-demanding events occur. Se-
lective attention is defined as the ability to focus atten-
tion in the face of distracting or competing stimuli. Di-
vided attention is required to respond simultaneously to
multiple tasks or multiple task demands. Shifting refers
to the ability to flexibly shift the focus of attention in
order to control which information from competing
sources will be selectively processed.
Alertness. While one study revealed a negative impact
of gum chewing on alertness [6], the remaining two
studies examining alertness found no indications of any
effects of gum chewing [5,15]. However, an improve-
ment of processing speed was observed in a condition in
which gum was chewed prior to testing and in which the
actual assessment took place early within the testing ses-
sion [16].
Sustained attention/Vigilance. A beneficial effect of
gum chewing was observed on sustained attention [6].
Chewing gum counteracted the decline of attentional
functioning over time which is considered normal in con-
tinuous tasks requiring attention [29]. However, Kohler
and colleagues [31] reported adverse effects of gum
chewing (a piece of Parafilm) on vigilance performance
in participants following sleep deprivation. This is con-
firmed by Tucha and colleagues [32] who also found
detrimental effects of gum chewing on vigilance per-
formance in both healthy children (mean age: 10.6 years)
and children with attention deficits (mean age: 10.8
years). Taenzer and colleagues [33] showed that 8 to 9
year old children performed more poorly on a sustained
attention task than children who did not chew gum. This
negative effect was only observed during the first 12
minutes of the test. During the remaining test duration of
four minutes children in the no-gum-condition were out-
performed by children in the gum-condition indicating a
beneficial effect of gum chewing on sustained attention.
The importance of time on task performance as a modi-
fying factor of the effects of gum chewing on sustained
attention has also been shown on an adult sample [34].
While gum chewing had detrimental effects on sustained
attention in earlier stages of a sustained attention task,
beneficial effects were observed at later stages of the task.
Smith [14] found that his participants performed signifi-
cantly better on a sustained attentio n task whilst chewing
gum than in the condition withou t gum despite not tak ing
time-on-task into account. In a previous study, however,
Smith [15] could not find such an effect. Furthermore,
Wilkinson and colleagues [5] found no effects of gum
chewing on vigilance.
Selective attention. Rost and colleagues [2] performed
two experiments on large samples of children (n > 500
children each; mean age: 11.0 and 11.4 years respec-
tively) and found in one experiment no effect of gum
chewing on selective attention (concentration) but a det-
rimental effect on selective attention in the other experi-

Gum Chewing and Cognition: An Overview 247
ment. Smith [14] observed an advantageous effect of
gum chewing. Furthermore, Stephens and Tunney [9] re-
gistered an improvement of selective attention induced
by gum chewing in one of the three measures these au-
thors applied to assess selective attention. This is con-
firmed by the results of Sakamoto and colleagues [35]
who found improvements of focused attention (as as-
sessed with an auditory oddball paradigm) when partici-
pants chewed gum. Three other studies failed to find any
effects of gum chewing on selective attention [5,6 ,15].
Divided attention. Divided attention was examined by
Tucha and colleagues [6] who found no effects of gum
chewing on this attention function .
Shifting. Shifting of attention was examined in two
studies. In one of these studies shifting was significantly
impaired by gum chewing [6] while in the other study no
effects were found [9].
Summary of studies examining the effect of gum chew-
ing on attention. Twelve studies examined the effects of
gum chewing on aspects of attention. The majority of
studies focused only on single aspects of attention. A
comprehensive assessment of all above mentioned com-
ponents of attention was so far only performed in one
study [6]. Four studies reported that gum chewing pro-
voked improvements of single aspects of attention, i.e.
sustained attention/vigilance [6,14] and selective atten-
tion [9,14,35]. In contrast to these findings, four studies
revealed detrimental effects of gum chewing on attention
functions such as alertness [6], sustained attention/vigi-
lance [31,32], selective attention [2]) and shifting [6].
Furthermore, five studies failed to find evidence that gum
chewing affects alertness [5,15], sustained attention/
vigilance [5,15], selective attention [2,5,6,15], divided
attention [6] and shifting [9]. An interesting observation
was made by Taenzer and colleagues [33] and Tucha and
Simpson [34] who demonstrated that time appeared to be
a meaningful factor in the psychodynamics of gum
chewing. On the basis of their results, one may assume
that chewing gum during task execution might impair
performance at early stages but improve performance at
late stages of cognitive tasks. In contrast, Onyper and
colleagues [16] observed in their study that gum chewing
only affected cognition favorably when gum was chewed
prior to cognitive assessment and when cognitive as-
sessment was performed within the period of 15 - 20
minutes after gum chewing. Our current knowledge,
however, is still very limited. In this respect, future re-
search evaluating the effects of gum chewing on cogni-
tive functioning should take time as a mediating factor
into consideratio n.
3.4. Executive Functions
Executive functions is an umbrella term encompassing
various functions of higher cognition including planning
and problem solving, attentional control, cognitive flexi-
bility, working memory and the goal-directed initiation,
monitoring and inhibition of actions [36]. In total, seven
studies examined the effect of gum chewing on various
aspects of executive functioning.
Working memory. Five studies assessed working
memory. Working memory is the ability to actively store
and manipulate information that is required for complex
cognitive tasks. While a few studies [5,9,16] reported
beneficial effects of gum chewing on working memory
(verbal, spatial and/or numeric working memory), Smith
[14] found that gum chewing resulted in an impaired
performance on a verbal working memory task. Spatial
working memory was not affected by gum chewing in
two studies performed by Smith [14,20].
Divergent thinking. Divergent thinking is a fluent,
creative and original process of problem solving which
aims for the production of as many appropriate solutions
to a certain problem as possible. In neuropsychological
assessment, divergent thinking is usually assessed with
verbal fluency tasks [36 ] which require the participant to
produce as many different words as possible according to
a lexical rule (e.g. beginning with a certain letter) or a
semantic rule (e.g. belonging to a certain category, such
as animals). Studies on verbal fluency functions failed to
find any effects of gum chewing on both lexical [9] and
semantic verbal fluency [16].
Reasoning. The cognitive process of reasoning allows
individuals to go beyond the information given and to
generate conclusions from information, assumptions and
premises. In two studies, measures of reasoning were
applied, however no effects of gum chewing could be
demonstrated on both children and adults [2,31].
Cognitive flexibility. Cognitive flexibility refers to an
individual’s ability to switch cognitive or behavioral re-
sponses in order to perceive, process and respond to chang-
ing environmental cond itions in adaptive ways. Using an
anagram task, Torney and colleagues [37] found no ef-
fect of gum chewing on cognitive flexibility.
Summary of studies examining the effect of gum chew-
ing on executive functioning. The results of three studies
indicated that gum chewing can induce an improvement
of working memory [5,9,16]. In contrast to these findings,
one study found detrimental effects of gum chewing on
working memory [14]. Another study by the same author
[20] failed to reveal any effect of gum chewing on work-
ing memory. No impact of gum chewing was found on
divergent thinking [9,16], reasoning [2,31] and cognitive
flexibility [37].
3.5. Spatial Skills
Spatial skills subsume a number of abilities such as spa-
tial orientation, perception of spatial relations (e.g. be-
tween objects), spatial imagination and mental spatial

Gum Chewing and Cognition: An Overview
248
manipulation (e.g. mental rotation of a map). Nader and
colleagues [38] applied in two experiments a task meas-
uring aspects of spatial perception and spatial imagina-
tion but observed no significant effects of gum chewing
on these abilities. However, the mean scores measured in
both experiments denoted poorer task performance when
participants chewed gum.
3.6. Intellectual Functioning
The term “intellectual functioning” as it is used here re-
fers to cognitive abilities or scores that cannot be easily
classified in the categories of functions as used above.
These abilities (mathematical skills) and scores (intelli-
gent quotient) might be highly dependent on and related
to some of the above mentioned functions (e.g. working
memory).
IQ. Smith [20] demonstrated that gum chewing re-
sulted in improved scores in an intelligence test (Alice
Heim 5 Test).
Mathematical skills. While two studies did not find
any effects of gum chewing on mathematical skills of
children [2,19], Johnston and colleagues [39] could
demonstrate that gum chewing during class and home-
work time (over a period of 14 days) significantly im-
proved math scores and math grades of adolescents
(mean age: 14.6 years).
Retrieval of information from general knowledge.
Smith [14] applied a semantic processing task which
requires participants to decide whether statements were
true or false. Data analysis revealed that gum chewing
resulted in a reduced speed and accuracy.
Verbal comprehension. Rost and colleagues [2] exam-
ined children’s understanding of word meanings but
found no effects of gum chewing.
Summary of studies examining the effect of gum chew-
ing on intellectual functioning. In conclusion, no effects
of gum chewing were observed on verbal comprehension
[2]. However, semantic processing was negatively af-
fected by gum chewing [14]. Positive effects were found
on an intelligence measure [20]. Since successful com-
pletion of this intelligence test depends largely on rea-
soning skills, this finding may not be in accordance with
the findings on reasoning as discussed above. Further-
more, one study reported beneficial influence of gum
chewing on math scores [39], while two studies failed to
find any effect [2,19].
4. Discussion
The present review reveals that there are clear indications
that gum chewing can improve various aspects of cogni-
tive functioning including memory, attention and both
executive and intellectual functio ning. However, it has to
be stressed that there is also clear evidence that chewing
gum during cognitive tasks can adversely affect task
performance. Furthermore, a number of well-controlled
studies failed to find any eff ects of gum chewing on cog-
nition. In this context, it has to be considered that the
reported number of studies finding no effects of gum
chewing is most likely conservativ e, since null results are
difficult to publish [18]. Therefore, it can be concluded
that the replication of (beneficial or detrimental) effects
of gum chewing on cognition has been proven to be very
difficult. The robustness of reported findings concerning
the effects of gum chewing on cognition has to be ques-
tioned. This conclusion clearly contradicts a previous
overview of the literature in which a facilitation of mem-
ory functions by gum chewing has been suggested to be a
robust pheno menon [1].
It would be interesting to find out why available stud-
ies differ so much in their results, in particular since a
number of studies applied very similar designs and test
procedures (e.g. word lists). There was a discussion
about methodological differences between the earlier
studies [1,21,40,41]. However, subsequent research
which considered variables that were assumed to influ-
ence the outcome of studies (e.g. way of presentation of
word lists, chewing habits of participants, research de-
sign) also failed to replicate the findings of previous
studies. In this context, three conclusions appear to be
important. First, some authors had difficulties to rep licate
previous research although their studies were close rep-
lications of previous work (e.g. [10,13]). Second, the
same authors found performance enhancing or decreas-
ing effects of gum chewing on cognition in one of their
studies but not in another study (e.g. [14,20]). Third,
some studies found both positive as well as negative ef-
fects of gum chewing on different aspects of cognition
within the same sample (e.g. [6,14]). It therefore appears
that the variables which were assumed to be responsible
for different outcomes of studies are not the crucial ones.
This review demonstrated that a number of studies
failed to reach statistical significance indicating positive
or negative effects of gum chewing on certain aspects of
cognition. Since the classical test theory defines the cir-
cumstances that lead to rejection or non-rejection of the
null hypothesis and since a non-rejection of the null hy-
pothesis does not express that no differences exist in the
population [42,43], one might argue that these stud ies do
not help in the discussion whether gum chewing is bene-
ficial or detrimental with regard to cogn itive functioning.
However, these studies clearly support the conclusion
that the effects of gum chewing are difficult to replicate
and not very robust .
Since cognition enhancing effects of gum chewing are
possible under certain conditions, the aim of future stud-
ies should be to identify these specific conditions, factors
and circumstances. In this respect, an interesting research

Gum Chewing and Cognition: An Overview 249
question might refer to the role of time as a mediating
factor in the psychodynamics of gum chewing. Future
research should also try to explain why gum chewing has
an impact on some functions but not on others. For ex-
ample, Wilkinson and colleagues [5] found in the same
participants memorial facilitation of gum chewing with
regard to verbal memory but not with regard to figural
memory. Furthermore, it would be interesting to know
whether gum chewing has the potential to facilitate
learning of more complex information than short word
lists. Word list learning (often with only one learning
trial) is a very specific task used in experimental research
which does not resemble learning in real life situations.
Consequently, current research results lack ecological
validity. The study of Johnston and colleagues [39] who
examined standardized math scores within the school
setting are therefore of particular importance. In case that
gum chewing really has this potential, we would know
that the effect of gum chewing on cognition is not only
interesting from an academic perspective but also from
an applied perspective, allowing us to recommend gum
chewing as some kind of cognitive enhancer. However,
since we lack all this information so far and because det-
rimental effects of gum chewing were repeatedly docu-
mented, gum chewing should not be considered as a
learning aid or cognitive enhancer.
REFERENCES
[1] A. Scholey, “Chewing Gum and Cognitive Performance:
A Case of a Functional Food with Function but No
Food?” Appetite, Vol. 43, No. 2, 2004, pp. 215-216.
doi:10.1016/j.appet.2004.07.004
[2] D. H. Rost, L. Wirthwein, K. Frey and E. Becker,
“Steigert Kaugummikauen das Kognitive Leistungsver-
moegen? Zwei Experimente der Besonderen Art [Does
Chewing Gum Enhance Cognitive Abilities? Two Rather
Extraordinary Experiments],” Zeitschrift Fur Padago-
gische Psycholog ie, Vol. 24, No. 1, 2010, pp. 39-49.
doi:10.1024/1010-0652/a000003
[3] K. L. Allen, D. Galvis and R. V. Katz, “Evaluation of
CDs and Chewing Gum in Teaching Dental Anatomy,”
New York State Dental Journal, Vol. 72, 2006, pp. 30-33.
[4] K. L. Allen, R. G. Norman and R. V. Katz, “The Effect of
Chewing Gum on Learning as Measured by Test Per-
formance,” Nutrition Bulletin, Vol. 33, 2008, pp. 102-107.
doi:10.1111/j.1467-3010.2008.00697.x
[5] L. Wilkinson, A. Scholey and K. Wesnes, “Chewing Gum
Selectively Improves Aspects of Memory in Healthy Vol-
unteers,” Appetite, Vol. 38, No. 3, 2002, pp. 235-236.
doi:10.1006/appe.2002.0473
[6] O. Tucha, L. Mecklinger, K. Maier, M. Hammerl and K.
W. Lange, “Chewing Gum Differentially Affects Aspects
of Attention in Healthy Subjects,” Appetite, Vol. 42, No.
3, 2004, pp. 327-329. doi:10.1016/j.appet.2004.01.003
[7] C. Miles, R. Charig and H. Eva, “Chewing Gum as Con-
text: Effects in Long-Term Memory,” Journal of Behav-
ioral and Neuroscience Research, Vol. 6, 2008, pp. 1-5.
[8] M. Fang, J. C. Li, G. Lu, X. Y. Gong and D. T. Yew, “A
fMRI Study of Age-Related Differential Cortical Patterns
during Cued Motor Movement,” Brain Topography, Vol.
17, No. 3, 2005, pp. 127-137.
doi:10.1007/s10548-005-4446-5
[9] R. Stephens and R. J. Tunney, “Role of Glucose in Chew-
ing Gum-Related Facilitation of Cognitive Function,”
Appetite, Vol. 43, No. 2, 2004, pp. 211-213.
doi:10.1016/j.appet.2004.07.006
[10] J. R. Bak er, J. B. Be zance, E. Zellaby and J. P. Aggleton,
“Chewing Gum Can Produce Context-Dependent Effects
upon Memory,” Appetite, Vol. 43, No. 2, 2004, pp. 207-
210. doi:10.1016/j.appet.2004.06.004
[11] C. Miles and A. J. Johnson, “Chewing Gum and Con-
text-Dependent Memory Effects: A Re-Examination,”
Appetite, Vol. 48, No. 2, 2007, pp. 154-158.
doi:10.1016/j.appet.2006.07.082
[12] A. J. Johnson and C. Miles, “Chewing Gum and Con-
text-Dependent Memory: The Independent Roles of
Chewing Gum and Mint Flavour,” British Journal of
Psychology, Vol. 99, 2008, pp. 293-306.
doi:10.1348/000712607X228474
[13] A. J. Johnson and C. Miles, “Evidence against Memorial
Facilitation and Context-Dependent Memory Effects
through the Chewing of Gum,” Appetite, Vol. 48, No. 3,
2007, pp. 394-396. doi:10.1016/j.appet.2006.10.003
[14] A. Smith, “Effects of Chewing Gum on Cognitive Func-
tion, Mood and Physiology in Stressed and Non-Stressed
Volunteers,” Nutritional Neuroscience, Vol. 13, No. 1,
2010, pp. 7-16.
doi:10.1179/147683010X12611460763526
[15] A. Smith, “Effects of Caffeine in Chewing Gum on Mood
and Attention,” Human Psychopharmacology-Clinical
and Experimental, Vol. 24, No. 3, 2009, pp. 239-247.
doi:10.1002/hup.1020
[16] S. V. Onyper, T. L. Carr, J. S. Farrar and B. R. Floyd,
“Cognitive Advantages of Chewing Gum. Now You See
Them, Now You Don’t,” Appetit e, Vol. 57, No. 2, 2011,
pp. 321-328. doi:10.1016/j.appet.2011.05.313
[17] M. Wada, Y. Hoshi, Y. Iguchi and I. Kida, “Near-Infrared
Spectroscopic Study on the Effects of Chewing on
Short-Term Memory,” Appetite, Vol. 57, No. 3, 2011, pp.
749-752. doi:10.1016/j.appet.2011.08.018
[18] M. D. Kozlov, R . W. Hughe s and D. M. Jone s, “Gummed-
Up Memory: Chewing Gum Impairs Short-Term Recall,”
The Quarterly Journal of Experimental Psychology, Vol.
65, No. 3, 2012, pp. 501-513.
doi:10.1080/17470218.2011.629054
[19] Z. Houcan and W. Li, “Effects of Chewing Gum on
Learning and Memory,” China Journal of Health Psy-
chology, Vol. 15, 2007, pp. 518-520.
[20] A. Smith, “Effects of Chewing Gum on Mood, Learning,
Memory and Performance of an Intelligence Test,” Nutri-
tional Neuroscience, Vol. 12, No. 2, 2009, pp. 81-88.
doi:10.1179/147683009X423247
[21] A. Scholey, “Further Issues Regarding the Possible

Gum Chewing and Cognition: An Overview
250
Modulation of Cognitive Function by the Chewing of
Gum: Response to Stephens and Tunney (2004) and Tu-
cha et al. (2004),” Appetite, Vol. 43, No. 2, 2004, pp.
221-223. doi:10.1016/j.appet.2004.08.004
[22] D. R. Godden and A. D. Baddeley, “Context-Dependent
Memory in 2 Natural Environments: Land and Underwa-
ter,” British Journal of Psychology, Vol. 66, 1975, pp.
325-331. doi:10.1111/j.2044-8295.1975.tb01468.x
[23] S. M. Smith and E. Vela, “Environmental Context-De-
pendent Memory: A Review and Meta-Analysis,” Psy-
chonomic Bulletin & Review, Vol. 8, No. 2, 2001, pp.
203-220. doi:10.3758/BF03196157
[24] A. A. Overman, J. Sun, A. C. Golding and D. Prevost,
“Chewing Gum Does Not Induce Context-Dependent
Memory When Flavor Is Held Constant,” Appetite, Vol.
53, No. 2, 2009, pp. 253-255.
doi:10.1016/j.appet.2009.06.013
[25] M. Leclercq, “Theoretical Aspects of the Main Compo-
nents and Functions of Attention,” In: M. Leclercq and P.
Zimmermann, Eds., Applied Neuropsychology of Atten-
tion: Theory, Diagnosis and Rehabilitation, Psychology
Press, New York, 2002, pp. 3-55.
[26] M. I. Posner and S. J. Boies, “Components of Attention,”
Psychological Review, Vol. 78, No. 5, 1971, pp. 391-408.
doi:10.1037/h0031333
[27] M. M. Sohlberg and C. A. Mateer, “Introduction to Cog-
nitive Rehabilitation: Theory and Practice,” Guilford,
New York, 1989.
[28] A. F. Mirsky, B. J. Anthony, C. C. Duncan, M. B. Ahearn
and S. G. Kellam, “Analysis of the Elements of Attention:
A Neuropsychological Approach,” Neuropsychology Re-
view, Vol. 2, 1991, pp. 109-145.
doi:10.1007/BF01109051
[29] R. A. Cohen, “The Neuropsychology of Attention,” Ple-
num Press, New York, 1993.
[30] A. H. Van Zomeren and W. H. Brouwer, “Clinical Neu-
ropsychology of Attention,” Oxford University Press,
New York, 1994.
[31] M. Kohler, A. Pavy and C. Van Den Heuvel, “The Effects
of Chewing versus Caffeine on Alertness, Cognitive Per-
formance and Cardiac Autonomic Activity during Sleep
Deprivation,” Journal of Sleep Research, Vol. 15, No. 4,
2006, pp. 358-368.
doi:10.1111/j.1365-2869.2006.00547.x
[32] L. Tucha, W. Simpson, L. Evans, L. Birrel, T. A. Sontag,
K. W. Lange and O. T ucha, “Detrimental Ef fects of Gum
Chewing on Vigilance in Children with Attention Deficit
Hyperactivity Disorder,” Appetite, Vol. 55, No. 3, 2010,
pp. 679-684. doi:10.1016/j.appet.2010.10.001
[33] U. Taenzer, A. von Fintel and T. Eikermann, “Chewing
Gum and Concentration Performance,” Psychological
Reports, Vol. 105, No. 2, 2009, pp. 372-374.
doi:10.2466/pr0.105.2.372-374
[34] L. Tucha and W. Simpson, “The Role of Time on Task
Performance in Modifying the Effects of Gum Chewing
on Attention,” Appetite, Vol. 56, No. 2, 2011, pp. 299-
301. doi:10.1016/j.appet.2010.12.021
[35] K. Sakamoto, H. Nakata and R. Kakigi, “The Effect of
Mastication on Human Processing: A Study Using Event-
Related Potentials,” Clinical Neurophysiology, Vol. 120,
No. 1, 2009, pp. 41-50. doi:10.1016/j.clinph.2008.10.001
[36] M. D. Lezak, D. B. Howieson and D. W. Loring, “Neu-
ropsychological Assessment,” Oxford University Press,
New York, 2004.
[37] L. K. Torney, A. J. Johnson and C. Miles, “Chewing Gum
and Impasse-Induced Self-Reported Stress,” Appetite, Vol.
53, No. 3, 2009, pp. 414-417.
doi:10.1016/j.appet.2009.07.009
[38] I. W. Nader, G. Gittler, K. Waldherr and J. Pietschnig,
“Chew on This: No Support for Facilitating Effects of
Gum on Spatial Task Performance,” Archives of Oral Bi-
ology, Vol. 55, No. 9, 2010, pp. 712-717.
doi:10.1016/j.archoralbio.2010.06.008
[39] C. A. Johnston, C. Tyler, S. A. Stansberry, J. P. Moreno
and J. P. Foreyt, “Gum Chewing Affects Standardized
Math Scores in Adolescents,” Journal of Adolescents, Vol.
35, No. 2, 2012, pp. 455-459.
doi:10.1016/j.adolescence.2011.04.003
[40] R. Stephens and R. J. Tunney, “How Does Chewing Gum
Affect Cognitive Function? Reply to Scholey (2004),”
Appetite, Vol. 43, No. 2, 2004, pp. 217-218.
doi:10.1016/j.appet.2004.07.005
[41] O. Tucha, L. Mecklinger, M. Hammerl and K. W. Lange,
“Effects of Gum Chewing on Memory and Attention: Re-
ply to Scholey (2004),” Appetite, Vol. 43, No. 2, 2004, pp .
219-220. doi:10.1016/j.appet.2004.08.003
[42] J. Cohen, “Statistical Power Analysis for the Behavioral
Sciences,” Erlbaum, Hillsdale, 1988.
[43] E. J. Pedhazur and L. P. Schmelkin, “Measurement, De-
sign, and Analysis: An Integrated Approach,” Lawrence
Erlbaum, Hillsdale, 1991.