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Research has shown chewing gum improves attention, although the mechanism for this effect remains unclear. This study investigated the effects and after-effects of chewing gum on vigilance, mood, heart rate and EEG. Participants completed a vigilance task four times; at baseline, with or without chewing gum, and twice post-chewing. EEG alpha and beta power at left frontal and temporal lobes, subjective mood and heart rate were assessed. Chewing gum quickened reaction time and increased the rate of correct target detections, although correct detections fell during the second post-chewing task. Chewing gum heightened heart rate, but only during chewing. Gum also increased beta power at F7 and T3 immediately post-chewing, but not following the post-chewing tasks. The findings show that chewing gum affects several different indicators of alertness.
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Effects and after-effects of chewing gum on vigilance, heart rate, EEG
and mood
Andrew P. Allen
, Tim J.C. Jacob
, Andrew P. Smith
Centre for Occupational and Health Psychology, School of Psychology, Cardiff University, 63 Park Place, CF10 3AS, United Kingdom
School of Biosciences, Cardiff University, Life Sciences Building, Museum Avenue, CF10 3AX, United Kingdom
Chewing gum shortens vigilance reaction time.
Vigilance accuracy increases during chewing.
Heart rate increases during chewing.
Chewing gum increases temporal and frontal beta power.
abstractarticle info
Article history:
Received 10 October 2013
Received in revised form 3 April 2014
Accepted 14 May 2014
Available online 21 May 2014
Sustained a ttention
Chewing gum
Heart rate
Research has shown that chewing gum improves attention, although the mechanism for this effect remains
unclear. This study investigated the effects and after-effects of chewing gum on vigilance, mood, heart rate and
EEG. Participants completed a vigilance task four times; at baseline, with or without chewing gum, and twice
post-chewing. EEG alpha and beta power at left frontal and temporal lobes, subjective mood and heart rate
were assessed. Chewing gum shortened reaction time and increased the rate of hits, although hits fell during
the secondpost-chewing task.Chewing gum heightened heart rate, butonly during chewing.Gum also increased
beta power at F7 and T3 immediately post-chewing, but not following the post-chewingtasks. The ndings show
that chewing gum affects several different indicators of alertness.
© 2014 Elsevier Inc. All rights reserved.
1. Introduction
The ability to sustain attention is crucial, and determines higher at-
tention function [25]. Vigilance, dened as sustained attention requiring
the production of a target response to an occasionally occurring stimu-
lus [37], is characterised by a vigilance decrement [15]; as attention is
sustained over time, performance worsens. The role of arousal in the
vigilance decrement is controversial: although vigilance performance
may decline due to reduced arousal [8], vigilance tasks can also be
stressful [40], which would imply that the decline in vigilance is due
to heightened arousal instead. Research on sustained attention has indi-
cated a fall in heart rate over time [23], and participants reported engag-
ing in other mental activities during the task, whichrefutes the idea that
attention resources are engaged but become overstretched during
Chewing gum could act as a relatively inexpensive and safe means of
enhancing sustained attention. Following conicting ndings on the ef-
fect of chewing gum on global performance measures from attention
tasks (e.g. [29,41]), studies have investigated the possibility that gum
chewing may affect sustained attention after a certain amount of time,
attenuating the vigilance decrement. Chewing gum has shortened reac-
tion time towards the end of a vigilance task [2,18,34],aswellas
improving accuracy ([29], secondary analysis) and schoolchildren com-
pleted a greater number of items towards the end of a concentration
task when chewing gum [33]. The fact that a benecial effect of chewing
is not immediately evident may be in part due to a distracting effect of
chewing gum during performance; however, such distraction may be
specic to people who have habituated to consuming chewing gum.
Consequently, habitual gum consumption should also be taken into
account. Despite numerous studies indicating a positive effect of gum
later in testing, a negative effect of gum was observed towards the
end of a vigilance task [1]; this might be due to a shorter testing period
being used than in research which showed a positive effect over time.
Physiology & Behavior 133 (2014) 244251
Corresponding author at:Room 5.35, Alimentary PharmabioticCentre/Department of
Psychiatry, Bio sciences Institute, University College Cork, Cork, Ireland. Tel.: + 44
E-mail addresses: (A.P. Allen), (T.J.C. Jacob), (A.P. Smith).
0031-9384/© 2014 Elsevier Inc. All rights reserved.
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Another study did not nd an interaction between gum condition and
rst versus second half of a vigilance task [35]. In another study,
chewing gum improved performance not simply towards the end, but
throughout a continuous performance test which involved producing
frequent responses and withholding a response occasionally [13],sug-
gesting that the time-on-task effect of chewing gum may be more evi-
dent in sustained attention tasks where the production of a response
is relatively rare. The effects of chewing gum on cognitive performance
have also been shown to persist after chewing has ceased [22]. The au-
thors suggest that this persistent change in performance is due to an on-
going effect of chewing on arousal. Consequently, it may be the case that
chewing gum for a short period at the beginning of a lengthy task can
attenuate a decline in vigilance, even if gum is no longer being chewed.
Our rst hypothesis was thus as follows:
Hypothesis 1. A decline in vigilance performance (evident in reduced
hits and lengthened reaction time on the vigilance task) will be attenu-
ated by chewing gum, compared to a no-chewing control.
Similar to competing theories of the role of arousal in the vigilance
decrement, it is also still unclear if chewing gum leads to increased or
reduced arousal; chewing gum has been found to increase subjective
alertness (e.g. [11,26,29]), but there is also evidence that chewing
gum can reduce anxiety, both over a period of two weeks (e.g. [43])
and under conditions of acute stress [28], and there is mixed evidence
regarding the effect of chewing on heart rate [27,36,39,41].Consequently,
a positive effect of chewing gum on vigilance may be due to either:
(1). Chewing gum restoring arousal after a vigilance task reduces arousal
to a sub-optimal level, or: (2). Chewing gum reducing arousal after a
vigilance task heightens arousal to an excessive level. By examining
physiological arousal, this study may help to elucidate which account of
vigilance and which putative mechanism of chewing gum are accurate.
A state of arousal is associated with increased beta activity and re-
duced alpha activity, while the opposite trends are associated with re-
laxation [16], although heightened beta activity was associated with
lower skin conductance levels in children with ADHD [5], suggesting
that indices of central nervous system and sympathetic nervous system
arousal may not correspond directly. EEG measures show differential
effects during sustained attention; beta power is associated with ten-
dency to respond [3], suggesting that a state of vigilance is associated
with heightened beta power. Beta power reductions in elderly adults
have been associated with poorer attentional performance [6], provid-
ing further evidence of an association between higher beta power
and higher attentional performance. Spearmint gum has heightened
alpha frequencies at T3, F3 and F4 during a post-chewing recording
[17]. Beta ratios of activity at T3 increased following the chewing of
avourless gum, suggesting that a more alert state was induced. How-
ever, beta ratios of activity fell at F4, and alpha rose at T3, following
chewing of gum with sucrose [16]. Chewing gumbase with sucrose led
to an increase in the ratio of alpha activity at T3 and F3 [19]. However,
following chewing of avoured gum this did not occur, although the
ratio of alpha activity increased at F4, and beta increased at T3. The
fact that chewing gum can increase both alpha and beta activity led to
the description of chewing gum as inducing a mental state of relaxed
concentration[16]. Studies of chewing gum and EEG examine the
EEG after chewing in order to eliminate movement artefacts.
EEG studies concerning chewing have generally examined brain
activity in the absence of a cognitive performance task. However, fMRI
research has indicated that chewing gum during performance of an
attention task is associated with activation in the left frontal gyrus and
anterior cingulate cortex (ACC) [10]. Furthermore, connectivity be-
tween the dorsal ACC and the left anterior insula has been found to be
attenuated when chewing gum under conditions of noise stress [42],
suggesting that a stress-reducing effect of gum on ACC function could
potentially explain positive effects on vigilance performance. More
generally, frontal and temporal activities have been associated with
sustained attention (e.g. [38]). Frontal and temporal areas are thus
promising candidate areas for chewing gum effects in the central
nervous system during attention performance. Our second hypothesis
was as follows:
Hypothesis 2. Consistent with a low-arousal model of vigilance, heart
rate, beta activity and subjective alertness will fall during vigilance per-
formance, and chewing gum's attenuation of the vigilance decrement
will be evident in higher heart rate, increased beta activity, and higher
subjective alertness.
The present research investigated the effects and after-effects of
chewing standard gumbase with sweeteners on vigilance performance
during and after chewing, as well as the effects of chewing on the activ-
ity of both the sympathetic nervous system (heart rateduring and
after chewing) and the central nervous system (EEGafter chewing).
This study also assessed changes in mood over the test session. Partici-
pants alternated between performing blocks of a vigilance task and
receiving brief EEG recordings. We hypothesised that chewing gum
would attenuate a reduction in vigilance performance, as well as associ-
ated changes in physiology (reduced heart rate and EEG beta power) and
subjective mood (reduced alertness).
2. Method
The research described in this paper received approval from Cardiff
University's School of Psychology Ethics Committee.
2.1. Design
Participants were divided into two groups by random assignment
to either a chewing or control condition. Participants in the chewing
condition chewed during the gum/control vigilance task that followed
baseline EEG (see Fig. 1).
2.2. Participants
Forty-eight right-handed participants were initially recruited, but
eight participants' EEG data had to be excluded due to movement arte-
facts. Forty participants were included in the nal study. Age, gender
and occupational status of participants in each group are summarised
in Table 1. Participants were recruited through an online university no-
tice board. Participants had normal or corrected-to-normal vision. They
were paid £10 forparticipation. Exclusion criteria were: medication use,
any self-reported medical problems, consumption ofmore than 40 units
of alcohol per week or smoking more than 10 cigarettes in the daytime
and evening.
2.3. Materials
2.3.1. Electroencephalography
Participants were seated in a comfortable chair in a quiet room. Ac-
cording to the international 10/20 system, silver electrodes were placed
in specic regions on the scalp (T3 and F7). Additionally, a reference elec-
trode was placed on the mastoid behind the left ear while the two earth
electrodes were positioned on the forehead and right arm. All the elec-
trodes were connected to an electrode adaptor box (Cambridge Electron-
ic Design CED1902, Cambridge, UK) followed by a pre-amplier/amplier
(CED1902, Cambridge, UK) before the signal was digitised (CED1401
laboratory interface) and stored on a computer for subsequent analysis.
2.3.2. Heart rate
ARBO ECG electrodes were used for the reference and earth
electrodes. A piezo-electric pulse transducer (UFI, CA, USA) was used
in conjunction with a CED 1401-plus laboratory interface to monitor
245A.P. Allen et al. / Physiology & Behavior 133 (2014) 244251
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heart rate. The monitor was attached to the nger of the participant's
non-dominant hand.
2.3.3. Gum
Wrigley's standard gumbase was used: this consisted of gum base,
glycerine, lecithin, sorbitol, sweeteners (aspartame and acesulfame K)
and emulsier.
2.3.4. Psychological tasks Repeated digits vigilance task [31].Three-digit numbers were
shown on the screen of a laptop at the rate of 100 per minute. Each
was normally different from the preceding one but on 8 trials per min-
ute the number presented was the same as that presented on the previ-
ous trial. Participants had to detect these repetitions and respond as
quickly aspossible bypressingthe central button on a purpose-built re-
sponse box. Digits were presented in white on a black background. Each
session of this task lasted 5 min 30 s. Previous research has shown that
performance on the task declines even when the task lasts for only 3
min. Correct detections of target repetitions (hits), incorrect button
presses when no repetition was presented (false alarms) and reaction
time were assessed. Mood (visual analogue scale). Self-reported alertness (range =
0400), hedonic tone (range = 0300) and anxiety (range = 0150)
were measured using visual analogue scales (previously used at our
laboratory, e.g. [2]) at baseline and at the end of testing. Using the same
response box used for the vigilance task, participants moved the cursor
left or right to describe the extent to which they felt a certain mood.
There was no time limit for this task.
2.4. Procedure
Testing took place either in the late morning (start time at 10:00,
11:00 or 12:00) or the afternoon (start time 15:00 or 16:00), so that
participants were not tested during periods of low circadian alertness.
Participants were requested not to eat for 1 h before entering the lab,
in order to avoid post-meal effects.
Participants signed a consent form and lled in a demographic ques-
tionnaire. Participants sat approximately 85 cm from the laptop screen.
A reference electrode was attached at the left mastoid. Test electrodes
were then placed at F7 and T3, followed by an earth on the right
forehead. An extra earth was attached to the left wrist. The heart rate
monitor was attached to the index nger of the left hand.
The stages of testing are summarised in Fig. 1. Following a
familiarisation with the computer tasks, participants performed a base-
line measure of mood and vigilance. The next vigilance task was
performed with or without chewing gum, and was followed by two
more vigilance tasks without chewing gum. EEG recording followed
each performance of the vigilance task. A post-test assessment of
mood followed the last EEG recording.
Heart rate was measured continuously from the beginning of the
baseline vigilance test until the end of the nal EEG measurement.
Participants in the chewing gum condition expectorated their gum im-
mediately after nishing the vigilance task with chewing. During EEG
readings, participants were instructed to rest their heads back in the
seat with their eyes closed, and to remain as still as possible, in order
to minimise muscle movement.
2.5. Analysis
Heart rate and EEG data were analysed using Spike 2, version 7.07.
Heart rate and EEG were visually inspected for artefacts, which were re-
moved from the analysis. EEG was analysedin 30 second epochs, which
were then averaged to give each 60 second post-vigilance EEG measure.
The two EEG frequency bands analysed werealpha, 8 to 13 Hz, and beta,
13 to 30 Hz.
Change-from-baseline data were analysed using ANOVA. The inde-
pendent variables were chewing gum condition and time-on-task, and
habitual gum consumption was also entered to test for interactions be-
tween experimental gum condition and habitual level of consumption.
For vigilance performance and EEG, a 2-factor (2 X 3) mixed design
was used, with the between-participants variables being gum condition
(2 levels: whether participants chewed or not during the second vigi-
lance task) and the within-participants variable being stage of testing
(3 levels: with/without chewing, post-chewing 1 and post-chewing
2). The dependent variables were hits, false alarms and reaction time
for vigilance performance, alpha power and beta power at F7 and T3
for EEG, and heart rate. For mood, a 2-factor (2 X 2) mixed design
was used, with gum condition as the between participants variable,
and the within-participants variable being stage of testing (2 levels:
pre-vigilance tasks and post-vigilance tasks). For heart rate, a 2-factor
(2 X 6) mixed design was used, with gum condition as the between
participants variable, and the within-participants variable being
stage of testing (6 levels: vigilance with/without chewing, EEG1, post-
chewing vigilance 1, EEG2, post-chewing 2 and EEG3). Furthermore,
the potential moderating effects of habitual gum consumption were
analysed using 2-factor (2 X 3) ANOVA with the additional between-
participants predictor of habitual gum consumption (3 levels: regular,
infrequent and never; see Section 3.4.). The dependent mood variables
were alertness, hedonic tone and anxiety. Scores that were three inter-
quartile ranges above the median were excluded from analysis.
3. Results
3.1. Effect of gum and time on reported mood
For mood, a 2 (gum condition: gum or control) × 2 (stage of testing:
pre-test and post-test) mixed ANOVA was conducted.
The main effect of gum condition was examined to determine the
overall effect of chewing gum; there was not a main effect on alertness,
(1, 38)
= .32, pN.05, partial η
= .01, hedonic tone, F
(1, 38)
= .26, pN.05,
partial η
= .01, or anxiety, F
(1, 38)
= .18, pN.05, partial η
= .01. The
main effect of time was investigated to determine if the vigilance task
itself altered mood. Regardless of gum condition, time led to a
highly signicant reduction in alertness, F
(1, 38)
= 72.75, pb.001, partial
Fig. 1. Order and approximate timings of conditions.
Table 1
Participant characteristics.
Gum condition No-gum control
Age 22.33 (SD = 2.5) 24.4 (SD = 3)
Gender Female = 16 Female = 16
Male = 2 Male = 6
Occupation Student = 16 Student = 16
Administrator = 1 Administrator = 3
Researcher = 1 Researcher = 1
Interpreter = 1
246 A.P. Allen et al. / Physiology & Behavior 133 (2014) 244251
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= .66, and hedonic tone, F
(1, 38)
= 22.36, pb.001, partial η
but not anxiety, F
(1, 38)
= .35, pN.05, partial η
= .01. The interaction
between chewing gum and time was tested to examine if gum could
moderate any time-on-task effects. There was an interaction between
gum condition and time; gum condition was associated with a signi-
cantly smaller reduction in alertness between baseline and post-test,
(1, 38)
=6.27, p= .02, partial η
=.14(seeFig. 2), although
there was no gum × time interaction for hedonic tone, F
(1, 38)
= 2.53,
pN.05, partial η
= .06, or anxiety, F
(1, 38)
= 2.8, p=.1,partial
= .07. The mean anxiety and hedonic tone scores are reported in
Table 2.
3.2. Effect of gum and time on vigilance performance
For vigilance performance, a2 (gum condition: gum or control) × 3
(stage of testing: with/without chewing, post-chewing 1 and post-
chewing 2) mixed ANOVA was conducted. For testing as a whole,
reaction time was shortened in the gum condition, F
(1, 38)
p= .05, partial η
= .07, but there was not a main effect of gum
condition on hits, F
(1, 38)
= .08, pN.05, partial η
= .002, or false alarms,
(1, 37)
= 1.09, pN.05, partial η
= .03. Stage of testing had a main effect
on repeated digits hits, which fell signicantly across sessions, F
(2, 76)
3.66, p= .03, partial η
= .09, as did false alarms, F
(2, 74)
= 2.63, p= .04,
partial η
= .07, indicating a lower overall response rate, although
there was no main effect of stage of testing on reaction time, F
(2, 76)
= 1.94, pN.05, partial η
= .05. There was an interaction between
chewing gum and stage of testing on hits, F
(2, 76)
= 2.71, p= .04, partial
=.07(seeFig. 3). Hits were higher for the gum condition during
chewing and at post 1, but slightly lower at post 2. There was no signif-
icant gum × time interaction for false alarms or reaction time.
3.3. The effect of gum and time on physiology
For heart rate data, a2 (gum condition: gum or control) × 6 (stage
of testing: vigilance with/without chewing, EEG1, post-chewing
vigilance 1, EEG2, post-chewing 2 and EEG3) mixed ANOVA was
conducted. Gum condition did not have a signicant main effect on
heart rate, F
(1, 32)
= .70, pN.05, partial η
= .02. However, heart rate
was signicantly affected by time, F
(1.84, 58.9)
= 16.77, pb.001, partial
= .34, Greenhouse-Geisser adjusted. Mean heart rate fell slightly
across the EEG testing sessions, but was substantially reduced for the
post-chewing vigilance tasks, compared to heart rate during the
vigilance task with chewing. Furthermore, there was a signicant
interaction between gum condition and time of testing for heart rate,
(1.91, 61.12)
= 8.51, p= .001, partial η
= 0.21, GreenhouseGeisser
adjusted. Gum led to a highly signicant increase in heart rate during
chewing, F
(1, 32)
= 48.59, pb.001, partial η
= 0.72, but there was a
lack of a difference between conditions later in the experiment,
although heart rate was somewhat lower for the gum condition during
the post-chewing vigilance tasks (see Fig. 4).
For EEG data, a 2 (gum condition: gum or control) × 3 (stage of test-
ing: with/without chewing, post-chewing 1 and post-chewing2) mixed
ANOVA was conducted. Chewing led to a non-signicant increase in
beta power at T3, F
(1, 28)
=1.95,pN.05, partial η
= .07, and at F7,
(1, 28)
=1.91,pN.05, partial η
= .06. Stage of testing did not
signicantly affect beta power at T3, F
(1.41, 39.39)
= .31, pN.05, partial
= 0.01, GreenhouseGeisser adjusted, or at F7, F
(1.22, 34.05)
pN.05, partial η
= 0.02, GreenhouseGeisser adjusted. There
was no signicant interaction between gum and stage of testing at T3,
(1.41, 39.39)
=1.41, pN.05, partial η
= 0.05, GreenhouseGeisser
adjusted, or at F7, F
(1.22, 34.05)
=.32,pN.05, partial η
= 0.01,
GreenhouseGeisser adjusted.
Although the interaction between gum condition and stage of test-
ing was not signicant, a speculative simple effects analysis indicated
that the effect of gum was signicant immediately post-chewing
(EEG1), both for T3, F
(1, 50)
= 5.73, pb.05, partial η
= 0.1, as well as
for F7, F
(1, 48)
= 11.57, pb.01, partial η
=0.19(seeFig. 5).
With regard to alpha power, chewing condition did not
have a main effect at T3, F
(1, 23)
= .59, pN.05, partial η
= 0.03, or at
F7, F
(1, 23)
=.59,pN.05, partial η
= 0.03. Stage of testing did not
have a signicant effect at T3, F
(2, 46)
=1.99,pN.05, partial η
or at F7, F
(2, 52)
= 1.43, pN.05, partial η
= 0.05. Gum condition did
not interact with stage of testing at T3, F
(2, 46)
= 1.05, pN.05, partial
= 0.04, or at F7, F
(2, 52)
=.13,pN.05, partial η
= 0.05.
3.4. Habitual gum consumption
To examine the potential moderating effects of habitual gum con-
sumption,2 (gum condition) × 3 (level of habitual consumption: regu-
lar, infrequent and never) mixed ANOVA were conducted. Consistent
with previous research [30], habitual chewing was classied as follows:
twenty-one participants chewed ve or more pieces of gum a week
(regular: median pieces chewed per week = 10, range = 521),
fourteen chewed gum, but fewer than ve pieces a week (infrequent:
median = 1.6, range = 0.252.5) and ve never chewed. Experimental
groups did not differ signicantly in the mean number of pieces chewed
per week. Habitual gum consumption did not moderate the effects of
gum on mood, vigilance performance, heart rate or EEG data.
Gum Control
Alertness rating (total VAS score)
Fig. 2. Effectof gum on change in alertness. (Error bars indicate standard error. Asteriskindicates signicantdifference (pb.05) in change in alertness. Maximumalertness score = 400.)
Table 2
Hedonic toneand anxiety for gum conditionsat pre- and post-test assessment. (Standard
errors in brackets.)
Gum No gum
Pre-test hedonic tone (maximum score = 300) 223.6 (8.6) 226.8 (7.2)
Post-test hedonic tone 206.7 (9.2) 192.8 (8.0)
Pre-test anxiety (maximum score = 150) 97.7 (4.3) 100.2 (4.6)
Post-test anxiety 101.0 (5.4) 93.2 (5.1)
247A.P. Allen et al. / Physiology & Behavior 133 (2014) 244251
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Chewing Post-chewing 1 Post-chewing 2
Chewing Post-chewing 1 Post-chewing 2
Number of false alarms
(Baseline change)
Chewing Post-chewing 1 Post-chewing 2
Number of hits
(Baseline Change)
Mean RT
(ms - Baseline change)
Fig. 3. Effect of gum across sessions on (A) hits, (B) false alarms and (C) mean reaction time for the repeated digits task. (Change scores from pre-chewing baseline are used. Error bars
indicate standard error.)
Chewing EEG1 Post-chewing 1 EEG2 Post-chewing 2 EEG3
HR (Beats per min - Baseline Change)
Fig. 4. Effectof gum on heart rate duringvigilance tasks andduring EEG readings. (Change scoresfrom pre-chewing baseline are used. Error bars indicatestandard error. Dagger indicates
signicant difference at pb.001.)
248 A.P. Allen et al. / Physiology & Behavior 133 (2014) 244251
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4. Discussion
This study indicates that chewing gum can alter central and sympa-
thetic nervous system activity associated with vigilance performance.
The transient effect on central and sympathetic nervous system arousal
is consistent with the short-lived effect of chewing gum on hits on the
vigilance task. The enhanced beta activity at F7 and T3 is consistent
with evidence suggesting that vigilance performance is associated
with frontal and temporal lobe activity (e.g. [9,38]), as well as fMRI
research indicating increased activation in frontal areas when
chewing gum during an attention task [10]. This article offers prelimi-
nary evidence that chewing gum may lead to a transient increase
in frontal and temporal beta activity, which is associated with an alert
state [16]. However, alpha activity was not affected by chewing
gum, in contrast to previous research which indicated that chewing
gum base increased alpha activity at the frontal and temporal regions
Some studies concerning chewing gum and vigilance have required
participants to chew gum for longer periods of time than used here
(e.g. [29]); the effects on vigilance performance reported here may
have been stronger and more persistent if participants had chewed for
longer. A condition in which participants make chewing movements
without any gum in their mouths (sham chewing) could be useful
for separating effects of chewing with mouth movements per se. How-
ever, previous research has indicated that, during a vigilance-type task,
the effects of sham chewing on both physiological and subjective mea-
sures of sleepiness were more similar to those of a no gum control
condition than those of gum [12], suggesting that motion alone may
not sufce to explain alerting effects of gum. Both females and males
were included as participants, as previous research has not indicated
sex differences in chewing gum effects [32].
A vigilance decrement was evident in vigilance performance, as well
as heart rate and subjective alertness. The reduction in heart rate as well
as hits and false alarms suggests that reduced vigilance was associated
with reduced sympathetic arousal. These ndings may not generalise
to all vigilance tasks; participants' self-reported mood indicated that
the current task did not heighten anxiety, but where a vigilance task in-
duces anxiety, different trends may be seen.
The recording of the EEG with eyes closed prevented trends in brain
activity during vigilance performance from being measured. This is un-
fortunate, as more complete data on central nervous system activity
could be observed, but this method was essential to remove artefacts as-
sociated with participants having their eyes open; the use of an auditory
vigilance task which can be performed with the eyes closed may allow
for recording of EEG data during vigilance performance in future
research. However, even in this case EEG cannot be measured while
chewing gum, as this will also create artefacts due to muscle movement.
Mood assessment could also be conducted at more frequent intervals to
gain greater information concerning any decline in alertness, although
longer breaks between stages of vigilance testing may result in less of
a decrement in vigilance [20], so interrupting testing stages for longer
periods to conduct mood assessments may lead to a recovery in
vigilance performance which could impair study of the vigilance
Beta power
(µV squared: change from baseline)
Beta power
(µV squared: change from baseline)
Fig. 5. Effectof gum on beta power (A) at T3 and(B) at F7. (Change scoresfrom pre-chewingbaseline are used. Errorbars indicate standard error. Asterisk indicates signicant differenceat
249A.P. Allen et al. / Physiology & Behavior 133 (2014) 244251
Author's personal copy
The smaller fall in alertness for the chewing condition is consistent
with previous research. However, baseline alertness happened to
already be lower in the gum condition, before the gum manipulation,
and it fell to a level similar to that of the control condition post-test.
Given this baseline difference, it is unclear from the current data if
chewing gum had a subjectively alerting effect. Chewing gum did not
affect anxiety, although this may be due to anxiety being close to oor
for participants, in contrast with research assessing the effect of
chewing gum under conditions of acute stress [28].
Previous research (e.g. [22]) and discussion of time-on-task trends in
chewing effects have suggested that an initial distracting effect (which
should become less evident as chewing becomes more automatic) may
be followed by enhanced arousal (which may persist after chewing has
ceased). The current ndings do not suggest an impairment of vigilance
by a distracting effect of chewing gum; indeed the interaction between
stage of testing and gum condition for hits suggests that chewing led to
higher accuracy while it was being chewed rather than following
chewing. There was a slight (non-signicant) trend for lower heart
rate in the gum condition at post-chewing; this may suggest that lower
sympathetic arousal could play a role in this interaction.
The major advantage of thisstudy is that it allowed for the measure-
ment of both central nervous system and sympathetic nervous system
arousal, along with the measurement of post-chewing effects which
occur after chewing has nished. Assuming a YerkesDodson inverted
U-shaped curve relationship between arousal and cognition, the fact
that heart rate was increased and reaction time was shortened by
gum suggests that participants were in a sub-optimal rate of arousal
when they completed the vigilance task (although see [7], for a critique
of the YerkesDodson law). As the reduction in response rate to the
vigilance task was associated with a fall in heart rate, our ndings
support the reduced arousal account of the vigilance decrement [8],as
opposed to an account whereby heightened arousal characterises
vigilance [40]. The fact that reaction time remained shortened by gum
compared to control, while the physiological effects were more
transient, suggests that some other mechanism may explain the more
persistent effects of reaction time. The fact that performance and phys-
iological indices of vigilance differed in their time course could be due to
compensatory control [14,24]; for example, participants in the control
condition may have maintained a slower rate of response (to avoid
making errors) due to an experienced reduction in arousal compared
to baseline.
Future research should examine the role of avour in chewing gum,
given existing evidence that it can have differing effects on EEG data
[16]. As brain activation in response to vigilance can be bilateral [9],
assessment of EEG trends on both sides of the brain will be of interest
in future research. It is also of interest if any neurochemical changes
are associated with chewing during sustained attention; noradrenaline
and acetylcholine have been suggested as playinga role in sustaining at-
tention [25], as well as dopamine, through its effects on motivation [21].
The enhancing effect of chewing gum on vigilance accuracy suggests
that it may be useful in a number of applied contexts, such as driving;
it has been suggested that this could be tested using driving simulation
techniques [29], similar to research assessing possible enhancing effects
of caffeine [4].
In conclusion, the ndings show that increases in both cardiovascular
and central nervous system arousal may explain the effects of gum on
vigilance, although the after-effects of chewing gum appear to be
time-limited. These effects were not moderated by habitual chewing
gum consumption, indicating they are not dependent upon familiarity
with chewing gum, and may potentially be useful in applied contexts
such as driving.
The rst author's PhD studies were supported by the Wrigley
Science Institute.
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... Furthermore, despite the finding that gum chewing improved alertness during the workday in the study conducted by Allen AP and Smith AP [50], it did not show any effect on HR. Conversely, Allen AP, Jacob TJ and Smith AP [51] noticed that gum chewing was associated with a decrease in HR, possibly reflecting an attenuation of sympathetic arousal. This was also associated with reductions in response rate in a vigilance task. ...
... The results from the above-mentioned studies suggest that gum chewing induces variations in arousal that relate to changes in cognitive performance according to an inverted U-shaped function [56]. However, the experimental ECG setup used by Allen AP, Jacob TJ and Smith AP [51] can be discussed as it may have biased the rating of alertness, which was quite high at baseline [53][54][55]. ...
... Future studies should take advantage of recent developments in wearable and portable devices to test the impact of dietary components in a real-world setting rather than a laboratory environment in which the participant can focus their attention on the experimental setup [63]. It is worth noting that this attention bias might have influenced the ECG-based testing of the effect of chewing gum in the study conducted by Allen AP, Jacob TJ and Smith AP [51], given the participants' high baseline subjective alertness. Real-world and real-time observations offer the chance to examine the ecological validity and robustness of existing health claims [64], as well as to substantiate new diet-health associations through the use of a large variety of study designs and intensive longitudinal data collection [65]. ...
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A growing body of literature suggests dietary components can support mood and cognitive function through the impact of their bioactive or sensorial properties on neural pathways. Of interest, objective measures of the autonomic nervous system—such as those regulating bodily functions related to heartbeat and sweating—can be used to assess the acute effects of dietary components on mood and cognitive function. Technological advancements in the development of portable and wearable devices have made it possible to collect autonomic responses in real-world settings, creating an opportunity to study how the intake of dietary components impacts mood and cognitive function at an individual level, day-to-day. In this paper, we aimed to review the use of autonomic nervous system responses such as heart rate or skin galvanic response to investigate the acute effects of dietary components on mood and cognitive performance in healthy adult populations. In addition to examining the existing methodologies, we also propose new state-of-the-art techniques that use autonomic nervous system responses to detect changes in proxy patterns for the automatic detection of stress, alertness, and cognitive performance. These methodologies have potential applications for home-based nutrition interventions and personalized nutrition, enabling individuals to recognize the specific dietary components that impact their mental and cognitive health and tailor their nutrition accordingly.
... • One study reported a positive correlation between alpha-band power and vigilance level (Chua et al., 2012). • Beta-band power decreases when vigilance performance decreases (Wang et al., 2017, Akin et al., 2004Papadelis et al., 2007;Allen et al., 2014). ...
... • HR decreases with a decrease in vigilance performance (Schmidt et al., 2007;Schmidt et al., 2011;Chua et al., 2012;Allen et al., 2014;Schmidt et al., 2009). ...
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... However, EEG lacks spatial resolution meaning that whilst a signal can be linked to a sensory event/task (such as eating), the specific part of the brain responding to that event cannot. EEG technology has been used by neuroscientists to study consumer behaviour , the effect of appearance (Toepel et al., 2009;Walsh et al., 2017) and flavour, taste and texture (Andersen, Kring, et al., 2019;Hashida et al., 2005;Horská et al., 2016;Labbe et al., 2011) on emotional and behavioural responses of food products, as well as the effect of food consumption on human brain functioning (Allen et al., 2014;De Pauw et al., 2017). Studies have shown a correlation between EEG results and hedonic attitudes measured through a questionnaire, with increased activation of the left hemisphere of the brain when the participant has a more positive attitude towards the food ( van Bochove et al., 2016). ...
This chapter covers some of the most popular emerging technologies used for measuring human behaviour in applied sensory and consumer science. Here, we focus on eye-tracking (ET) technology, electrodermal activity (EDA) or skin conductance, facial expression analysis (FEA) and electroencephalography (EEG), all of which can be employed to explore the underlying and at times unconscious processes of consumer behaviour. We walk through the methods traditionally used in sensory and consumer science and explain why, in isolation, they are incomplete. We provide insights into the basic principles of the different biometric technologies in focus, including objective quantification of attentional, emotional and neural correlates of consumer behaviour and food choice. We introduce state-of-the-art consumer research examples that utilise these biometric tools. Finally, we highlight some of the future potential applications in sensory and consumer science that these emerging technologies enable.
... [30] In addition to its impact on stress, chewing gum can affect alertness by a temporary increment in the beta function of the frontal and temporal areas, which is related to alerting conditions. [42] Research has demonstrated our daily life can be affected by alertness. [43] So, chewing gum can improve the quality of life by increasing alertness. ...
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There are various reasons for chewing gum, involving regulating psychological states such as concentration and alertness. More recent studies have shown inconsistent findings on the effects of chewing gum on stress reduction. This systematic review was conducted to investigate the effect of gum chewing on stress in different stressful situations in randomized controlled clinical trials. To find the main question in this study, the PICO strategy was applied. Multiple databases were systematically examined without considering time restrictions to perform relevant randomized controlled clinical trials of chewing gum and stress until February 2021. Of 108 papers found at the beginning of the study, only three studies were considered appropriate for a systematic review based on inclusion criteria. The results revealed that perceived stress is reduced due to chewing gum. Based on current evidence from three studies, chewing gum can reduce stress. Therefore, chewing gum can be recommended as a safe tool to alleviate stress.
... Chewing might relieve stress-induced anxiety by reducing the heart rate through the trigeminal cardiac reflex (Allen et al. 2014;Meuwly et al. 2015) and increasing cerebral blood flow to ensure sufficient glucose delivery (Stephens and Tunney 2004). However, the neural circuits underlying stress-relieving Data are shown as mean ± SEM. ...
Stressful stimuli can activate the hypothalamic-pituitary-adrenal (HPA) axis. Clinically, it has been widely reported that stressful events are often accompanied by teeth clenching and bruxism, while mastication (chewing) can promote coping with stress. Trigeminal motoneurons in the trigeminal motor nucleus supplying the chewing muscles receive direct inputs from interneurons within the peritrigeminal premotor area (Peri5). Previous studies found that the paraventricular hypothalamic nucleus (PVH) participates in trigeminal activities during stressful events. However, the neural pathway by which the stress-induced oral movements alleviate stress is largely unknown. We hypothesized that paraventricular-trigeminal circuits might be associated with the stress-induced chewing movements and anxiety levels. First, we observed the stress-coping effect of wood gnawing on stress-induced anxiety, with less anxiety-like behaviors seen in the open field test and elevated plus maze, as well as decreased corticosterone and blood glucose levels, in response to stress in mice. We then found that excitotoxic lesions of PVH reduced the effect of gnawing on stress, reflected in more anxiety-like behaviors; this emphasizes the importance of the PVH in stress responses. Anterograde, retrograde, transsynaptic, and nontranssynaptic tracing through central and peripheral injections confirmed monosynaptic projections from PVH to Peri5. We discovered that PVH receives proprioceptive sensory inputs from the jaw muscle and periodontal ligaments, as well as provides motor outputs via the mesencephalic trigeminal nucleus (Me5) and Peri5. Next, pathway-specific functional manipulation by chemogenetic inhibition was conducted to further explore the role of PVH-Peri5 monosynaptic projections. Remarkably, PVH-Peri5 inhibition decreased gnawing but did not necessarily reduce stress-induced anxiety. Moreover, neuropeptide B (NPB) was expressed in Peri5-projecting PVH neurons, indicating that NPB signaling may mediate the effects of PVH-Peri5. In conclusion, our data revealed a PVH-Peri5 circuit that plays a role in the stress response via its associations with oromotor movements and relative anxiety-like behaviors.
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... Therefore, chewing is often used for the process of checking the correct operation of the EEG device. Allen [10] and Pickworth [11] described in sufficient detail the process of recording the moment of chewing on an EEG encephalogram. Blinking with the eyes also causes an EOG artifact, which is less pronounced. ...
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The current study aimed to add to this of knowledge by examining the effect of chewing gum on smoking withdrawal severity over a long period, as well as identifying the specific characteristics of chewing gum that may be responsible for the reported reductions in withdrawal. Chewing, flavour, and the combination of the two were all investigated separately. The study is based on quantitative research. The data has been classified on basis of smoker and non-smoker. Participants reported a significant difference in withdrawal severity across conditions using repeated measures Chi square, F(3, 69)=2.89, p.05. The flavoured gum condition had considerably lower withdrawal scores than the flavourless gum base and no product control conditions, according to follow-up analyses. These data suggest that chewing gum is effective in reducing the severity of nicotine withdrawal symptoms over a 24-hour period of nicotine abstinence, and that the impact is due to a combination of flavour and chewing. These findings, together with findings from previous laboratory studies, show that chewing gum could be a useful coping mechanism for those who are trying to quit smoking.
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Introduction: Cognition is the mental process of acquiring knowledge and understanding through aspects such as awareness, perception, reasoning, memory and judgement. Chewing movement of jaw stimulates memory parts of brain by increasing blood flow and glucose delivery. Taste and odour of mint is also known to stimulate memory areas of the brain. The synergistic effect of chewing and flavour is expected to have a greater effect on cognition than chewing alone. Aim: To assess the effect of use of mint flavoured, flavourless and absence of chewing gum on an individual’s cognitive function among the medical undergraduates. Materials and Methods: This comparative, interventional study, was conducted in the Department of Physiology at Velammal Medical College and Hospital, Madurai, Tamil Nadu, India, August 2019 to September 2019. Study involved 75 (39 females, 36 males) MBBS first year students, aged 18-20 years. Only students with cognitive score between 28-30 based on MiniMental State Exam (MMSE) score were included in the study and were divided into 3 groups. Group A (n=25) who were given mint flavoured chewing gum, Group B (n=25) given flavourless chewing gum and Group C (n=25) the control group, not provided with chewing gum. Baseline memory, Heart Rate (HR), Reaction Time (RT) and Stress Levels (SL) were recorded. Groups were taken into separate rooms where they were allowed to study a particular topic i.e Parkinson’s disease for 30 minutes. Then they were allowed to take tests on standard Parkinson’s questionnaire for 20 minutes and assessed based on the test performance. Group A and Group B were provided with chewing gums both during studying the topic as well as taking tests. Post intervention test performance (short term memory), HR, RT and SL were again recorded. Test performance was also assessed after one month to assess the effect of chewing gum on long term memory. Oneway Analysis of Variance (ANOVA) and paired t-test were used to compare all the post test parameters between the three groups. Results: A statistically significant increase in short term memory (p-value=0.001) and HR (p-value=0.001) were observed after intervention. Similarly, short term memory level of the three groups subjects statistically differed (p-value=0.001). When considering the reaction time (p-value=0.068) and stress level (p-value=0.927), there was no significant difference among the three groups after the intervention. Assessment of the test scores alone after one month (long term memory) showed a significantly higher score (p-value
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Recent experiments investigating whether chewing gum enhances cognitive performance have shown mixed re-sults and a recent replication failed to reproduce earlier findings. The present experiment aimed to investigate whether participant individual differences underlie the discrepant findings. Therefore, in addition to examining differences in Digit Span and Spatial Span performance across gum and control groups, chronotype, extraver-sion, habitual tiredness, current stress, current arousal and current thirst were assessed using questionnaires. Task difficulty was also manipulated. While there were no chewing gum effects under standard testing condi-tions, chewing gum enhanced Digit Span performance in the more difficult dual task condition. Furthermore, Spatial Span performance was improved by chewing gum in introverts but not extraverts and chewing gum was shown to eliminate the negative relationship between thirst and Digit Span performance. In explaining these data it is proposed that chewing gum may act both to reduce stress and to alleviate thirst.
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Easterbrook’s (1959) cue-utilization theory has been widely used to explain the inverted U-shaped relationship, initially established by Yerkes and Dodson, between emotional arousal and performance. The basic tenet of the theory assumes that high levels of arousal lead to restriction of the amount of information to which agents can pay attention. One fundamental derivative of the theory, as typically conceived in psychology, is the assumption that restriction of information or the ability to process a smaller set of data is fundamentally disadvantageous. To explore the merits of this point, we first argue that the relationship depicted by this collapsed version of the Yerkes-Dodson law is far too simplistic to account for the complex relationship between various cognitive functions and emotional arousal. Second, conceptualization of arousal as a unidimensional construct needs to be rejected. Finally, and most importantly, we challenge the notion that having more information available is necessarily preferable to having less information.
We examine the impact of chewing gum on a Bakan-type vigilance task that requires the continual updating of short-term order memory. Forty participants completed a 30-min auditory Bakan-task either with, or without, the requirement to chew gum. Self-rated measures of mood were taken both pre- and post-task. As expected, the vigilance task produced a time-dependent performance decrement indexed via decreases in target detections and lengthened correct reaction times (RTs), and a reduction in post-task self-rated alertness scores. The declines in both performance and subjective alertness were attenuated in the chewing-gum group. In particular, correct RTs were significantly shorter following the chewing of gum in the latter stages of the task. Additionally, the gradients of decline for target detection and incline for correct RTs were both attenuated for the chewing-gum group. These findings are consistent with the data of Tucha and Simpson (2011), Appetite, 56, 299–301, who showed beneficial effects of chewing gum in the latter stages of a 30 min visual attention task, and extend their data to a task that necessitates the continuous updating of order memory. It is noteworthy that our data contradict the claim (Kozlov, Hughes, & Jones, 2012, Q. J. Exp. Psychology, 65, 501–513) that chewing gum negatively impacts short-term memory task performance.
The aim of this study was to investigate the neural basis of sustained attention, executive processing, and cognitive control in children with attention deficit hyperactivity disorder (ADHD). Event-related functional magnetic resonance imaging (fMRI) was used to compare brain activation of 28 medication-naïve children with ADHD aged 7-12years and 31 healthy controls during a cued continuous performance task (AX-CPT) in three stimulus context conditions (Go, NoGo, Lure). The children with ADHD showed increased activation in the left middle frontal gyrus, bilateral middle temporal gyrus, left precuneus and right cerebellum posterior lobe under the Lure condition compared to the controls. In the Lure condition, in contrast to the NoGo condition, an increased activation in the left inferior frontal gyrus, right medial frontal gyrus and right inferior parietal gyrus was observed in ADHD children. The results demonstrate that medication-naïve ADHD children show spatial and temporal abnormalities in neural activities involved in sustained attention and executive control. These findings show that there are distinct alternations in neural circuits related to sustained attention and executive control in children with ADHD, and further improve our understanding of the neural substrates of cognitive impairment in children with ADHD.
Past research has reported that a small proportion of children with Attention-Deficit/Hyperactivity Disorder (AD/HD) have excess beta activity in their EEG, rather than the excess theta typical of the syndrome. This atypical group has been tentatively labeled as hyperaroused. The aim of this study was to determine whether these children have a hyperaroused central nervous system. Participants included 104 boys aged 8 to 13 years old, with a diagnosis of either the Combined or Inattentive type of AD/HD (67 combined type), and 67 age-matched male controls. Ten and a half minutes of EEG and skin conductance (SCL) were simultaneously recorded during an eyes-closed resting condition. The EEG was Fourier transformed and estimates of total power, and relative power in the delta, theta, alpha, and beta bands, and the theta/beta ratio, were calculated. AD/HD patients were divided into an excess beta group and a typical excess theta group. Relative to controls, the typical excess theta group had significantly increased frontal total power, theta and theta/beta ratio, with reduced alpha and beta across the scalp. The excess beta group had significantly reduced posterior total power, increased centro-posterior delta, globally reduced alpha, globally increased beta activity, and globally reduced theta/beta ratio. Both AD/HD groups had significantly reduced SCL compared to the control group, but the two groups did not differ from each other on SCL. These results indicate that AD/HD children with excess beta activity are not hyperaroused, and confirm that the theta/beta ratio is not associated with arousal. This is the first study of arousal measures in AD/HD children with excess beta activity, and has implications for existing models of AD/HD.