1. Electrodermal Activity and Behavior in Adult Male and Female College Students
Barbara Brett*, Ricardo Unglaub+, Aaron Vialpando*, Tessa Luckini*, Alaura Butler*, Katie Freeman*,
Dustin Geist*, Jarrod Mason* & Kip Whitaker *
Departments of Psychology* and Physics/Engineering+, Colorado State University - Pueblo
Introduction
Methods
Discussion
References
Acknowledgements:
The authors would like to thank the Psychology Department and the students at CSU Pueblo for their support.
Due to the recognition of its potential to index hemispheric
specialization, interest in electrodermal activity (EDA) has
increased. EDA refers to autonomic changes in the electrical
properties of the skin (Bouscein, 2012). EDA specifically
indexes sympathetic arousal as it is the only autonomic
physiological variable that is not contaminated by
parasympathetic activity. The EDA complex includes both
tonic (skin conductance level; SCL) and phasic (skin
conductance response; SCR) components. SCL reflects the
overall degree of sympathetic arousal and decreases with
rest. SCRs are widely used to study sympathetic modulation
by attention, cognitive effort, and emotional arousal.
Most EDA studies assume there is symmetry between the
hands’ responses, collecting data from only the non-dominant
hand, while the other hand is used for clicking a mouse.
However, it is well-known that the organization of the
autonomic nervous system is lateralized, and research
indicates that EDA shows asymmetry under a variety of
stimulation conditions (Myslobodsky and Rattok, 1975; Banks
et. al., 2012). Further research suggests there may also be
gender differences in EDA asymmetry (Roman et al.,
1987,1989).
The purpose of the present study was to characterize
bilateral EDA in a population of adult male and female college
students during both rest and reading to examine the effects
of no attention and attention conditions.
Thirty adult college students between the ages of 18 – 53
years provided their voluntary consent to participate in this
study. Data reported is for 13 women (mean age = 26.5 years
, SD = 8.27) and 9 men (mean age = 29.56 years, SD =
10.64) who completed all required elements of this study.
Participants had their EDA recorded bilaterally. Females were
60% right-handed and 26.66% left-handed; Males were
66.66% right-handed, 11.11% left-handed, and 22.22 %
unknown. Participants also filled out a demographics
questionnaire and two self-reports.
A Biopac MP35 was used for exosomatic EDA recording.
Electrodes were positioned on the thenar and hypothenar
regions of both palms. Participants were asked to sit for 10
minutes to allow the electrode gel to soak into their skin.
Recordings were sampled at 200 Hz. Participants were then
asked: to relax during a 2 minute baseline period; to look at a
fixation point on a wall during one recording condition (rest, 5
minutes); and to read a textbook during the other recording
condition (reading, 5 minutes). The order of the conditions
was determined by the flip of a coin.
Average SCL was calculated across 3 minute time-
windows for each participant during each condition for both
the right and left hands. A MANOVA was used to examine
differences in SCL between the genders across the two
hands and two conditions. Post hoc tests were performed on
SCL data.
All experimental procedures were approved by the
institutional review board for human subjects research.
Overall, this study found significantly lower EDA on the left hand for
females compared to males during both rest and reading conditions.
This study also found significantly lower EDA for the left hand
compared to the right hand for both rest and reading conditions for
females-only.
Previous studies have also shown lateral electrodermal
asymmetry in typical adult subjects. In one study EDA was larger on
the right hand with verbal-numerical stimuli and on the left hand with
visual stimuli, indicative of hemispheric specialization (Myslobodsky
and Rattok, 1975). Studies have also shown gender differences in
EDA that resulted from males showing higher EDA on the left hand;
however findings have been equivocal. In a study by Roman et al.,
1987, the effects of gender on EDA were examined during three
conditions (rest, verbal task, and spatial task). Similar to this study, the
present study showed significantly higher EDA in males than females
on their left hand for both conditions. A subsequent study by Roman
et al., 1989 suggested their initial findings were related to hand
dominance and laterality at rest rather than gender; however, the
current study did not support this interpretation. In addition, Martinez-
Selva et al., 1987 found that during auditory stimulation, men showed
more asymmetry and higher EDA on the left hand, while females
showed less asymmetry and higher EDA on the right hand.
Assuming left hemisphere specialization for reading, one might
expect higher EDA on the right hand during the reading condition in
this study for both genders. Although this was found for females,
females also showed significantly higher EDA on the right hand for the
rest condition. This lack of a difference between conditions could be
due to purported less hemispheric specialization in females.
Moreover, the functional neuroanatomy underlying the central
regulation of EDA involves both ipsilateral and contralateral cortical
and subcortical controls and is not well understood (Banks et al.,
2012; Critchley, 2002).
A rest condition was included in this study for comparison with the
reading condition and to assess the default mode network (Raichle et
al., 2011). The default mode network is activated when a person is not
engaged in a task and is at rest, or daydreaming; it is deactivated by
attention to a task. A recent study found that changes in non-specific
SCRs were associated with the changes in the spontaneous activity of
the brain at rest (Fan et al., 2012). No difference in SCL was found
between rest and reading conditions for either gender in this study;
however, non-specific SCRs were not specifically examined.
Some goals for this research moving forward are to replicate this
study using a larger “n” and to collect data on laterality at rest as well
as hand dominance. We may also alter the rest condition to include no
fixation point and no specific instructions, and we may increase the
reading task demands to further differentiate the demands of the
conditions.
On average, SCL was higher for males across both hands and conditions compared to females. A
statistically significant difference was found in average SCL based on the participant’s gender: F
(4, 17) = 3.776, p = 0.022. Gender had an effect on SCL for both hand 2 (rest) F(1, 20) = 11.213,
p = 0.003 and hand 2 (reading) F(1, 20) = 11.543, p = 0.003. These results were significant at the
p < .0125 level corrected for multiple comparisons. Post hoc T-tests showed significant
differences in SCL between hand 1 and hand 2 for women during both conditions, p = .022 and p
= 035, respectively. No significant difference in SCL was found between the hands for men.
Results
Descriptive Statistics
SCL (µMho) Rest Reading
Hand 1 (right) Hand 2 (left) Hand 1 (right) Hand 2 (left)
Females
(n= 14)
3.28±3.09 SD 2.05±1.59 SD 3.07±3.14 SD 2.05±1.64 SD
Males
(n = 9)
5.50±4.41 SD 6.48±4.59 SD 5.61±4.62 SD 6.62±4.65 SD
Rest/Reading
Reading/Rest
Reading/Rest
Reading/Rest
EDA , measured in µMhos, is shown for 2 female (top) and 2 male (bottom) participants. The top
trace for each participant shows EDA recoded from the right palm (red), the bottom trace shows
EDA recorded from the left hand (blue). Each recording lasted 12 minutes and included a 2
minute baseline period and 2 randomly delivered experimental conditions (rest, reading) lasting 5
minutes each.
Male Participant #1RighthandLefthandRighthandLefthand
RighthandLefthandRighthandLefthand
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Neuroscience, 32(33), 11176-11186.
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man. Acta Psychologica, 41(4), 273-282.
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E. (1989). Sex differences and bilateral activity: a replication The Pavlovian
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Sex differences, activation level, and bilateral electrodermal activity The
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Shulman, G. L. (2001). A default mode of brain function. Proceedings of the
National Academy of Sciences, 98(2), 676-682.
Female Participant #1 Female Participant #2
Male Participant #2