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A psychophysiology study conducted at the University of Waterloo's Department of Psychology for an Undergraduate Honours Thesis.
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Arousal and cognitive load in Texas Hold ‘em poker
Psych 499C Honours Thesis
January, 2012
Student: Brendan Sheehan Faculty Advisor: Dr. Michael J. Dixon
University of Waterloo, Department of Psychology
Running Head: AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 1
Abstract
Texas Hold ‘em poker is one of the most popular gambling games today. A previous
study from our lab (Lee & Dixon) investigated whether the action of bluffing could be detected
overtly or covertly. Their results were unexpected and suggested cognitive load plays a crucial
role in the interpretation of arousal changes measured during strong hands, weak hands and bluff
hands. We replicated this study and added a subjective rating of arousal as a new measure to
assess their claims concerning cognitive load. The latter involved a baseline-mental arithmetic
task which used heart rate variability (HRV). Using the baseline-mental arithmetic task we found
a specific HRV variable, SDNN, was most sensitive to cognitive load. Applied to our study we
found no significant differences in SDNN between the three hand types – a finding which fails to
support Lee and Dixon’s cognitive load hypothesis. Importantly, we did replicate their HR
findings and showed that bluffing leads to as great an increase in arousal as a strong hand. We
contend that bluffing leads to high arousal. Given the strong theoretical link between arousal,
reinforcement and problem gambling, our findings may explain the popularity of this game, but
also sound a cautionary warning about a key game feature that could lead to gambling problems.
Key Terms: Texas Hold ‘em poker, Arousal, Cognitive Load, Heart Rate Variability
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 2
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER
Texas Hold ‘em is one variant of the family of card and betting games collectively known
as poker. Texas Hold ‘em is unique in that gameplay involves both cards known only to the
player as well as a set of communal cards which all players can act upon. In addition, the skill of
the player has at least some effect on the outcome of the game, as opposed to betting games of
pure chance such as roulette or slot machines (Shead, Hodgins, & Scharf, 2008). The game is
composed of four stages of play. First, each player is dealt two cards face down. Next, three
communal cards are dealt which all players can utilize. In the third and fourth round each, a
single communal card is dealt. As the game progresses the player has an increasing pool of
available cards from which to assemble the strongest possible combination of five cards (a hand).
The strength of the player’s assembled hand is in relation to a predefined order of hands,
standard throughout most variations of poker. After each of the four rounds of play, the player
must mentally estimate the probability of their hand winning. They must also approximate the
relative strength of their opponent’s hands. Based on these two mental estimates the player has
three options at each stage: decline further play (to fold), continue playing at the current level of
investment (to check) or, raise the level of investment (to raise). Each player must indicate their
decision in a predefined order (e.g. clockwise around the playing surface). If a player chooses to
raise, other players have the option to fold, to match the raise (to call) or to re-raise. Crucially,
the intensity with which a player bets does not necessarily correlate with the objective strength of
their hand. A player may decide to play a weak hand as if it were a strong one, in the hopes of
deceiving his or her opponents into folding (to bluff). This strategy is made possible because of
the two confidential player-dealt cards. Bluffing adds an extra interpersonal dynamic to the
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 3
game, as well as a considerable amount of excitement, as players must attempt to deceive their
opponents into believing their hand has a high probability of winning.
Texas Hold ‘em poker has grown immensely in popularity over the past decade. There are
over 60-80 million players in the US alone, a figure that continues to rise (The Economist, 2007).
Closer to home, over 20% of Ontarians play poker for money, 16% of whom play more than
once a week (RGC, 2006). Yet despite this tremendous, and growing, interest in Texas Hold ‘em
little is understood about the allure of the game. There is a dearth of empirical research
investigating what the attraction to Texas Hold ‘em is or which mechanisms lie behind its
addictive potentiality (Hopley & Nicki, 2010). We believe physiologic arousal may be involved
in both of these aspects of the game.
Arousal is a psychophysiological process linking signals from the environment with
somatic and physical state alterations, which serve to increase one’s ability to act upon their
environment. Fowles (1980) suggests that certain stimuli form links with specific mentations,
which ultimately bring about somatic and kinetic reactions (Fowles, 1980). These stimuli act
upon areas of the brain, including the reticular activating system (Steriade, 1996), causing acute
alterations in cardiovascular, autonomic nervous system and endocrine function within the body.
The net effect of processing these external signals is ultimately an increased ability of the
individual to act upon their environment in an adaptive manner (Woody & Szechtman, 2011).
As a concept, arousal appears throughout a considerable portion of the gambling
literature. Various mediums of gambling activity have been linked to alterations in physiological
arousal including: slot machines (Brown, Rodda, & Phillips, 2004; Dixon, Harrigan, Sandhu,
Collins, & Fugelsang, 2010), video poker machines (Leary & Dickerson, 1985), video lottery
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 4
terminals (Ladouceur, Sévigny, Blaszczynski, O'Connor, & Lavoie, 2003) and horse racing
(Cocco, Sharpe, & Blaszczynski, 1995). In addition, arousal features prominently throughout
problem gambling research. Blaszczynski and Nower (2002) included arousal in their influential
pathways model of problem gambling. They postulated that arousal acts as a reinforcer in both
an operant (e.g. intermittent wins) and in a classical (e.g. gambling stimuli, such as the “smell”
of a casino) conditioning sense (Blaszczynski & Nower, 2002). Sharpe et al. (1995) performed
an extensive analysis of arousal in both problem and non-problem gambling. They found that
gambling stimuli alone, even in the absence of any actual gambling activity, were sufficient to
evoke increases in physiologic arousal in problem gamblers (Sharpe, Tarrier, Schotte, & Spence,
1995).
Previous work in our lab (Lee & Dixon, unpublished) set out to examine a topic at the
forefront of most dedicated poker player’s minds: is it possible to tell, either overtly or with
physiologic measures, when a person is bluffing? Twenty-four healthy, non-problem gambler,
volunteers were tested in triads. Although the player’s believed the decks were completely
randomized, the game’s card decks were actually pre-arranged so that each participant would
receive two strong hands and four weak hands for a combined eighteen hands. Before play
commenced each participant was given confidential written instructions that, should they
encounter a specific weak hand, they were to bluff (to play the weak hand to win). Consequently,
within the eighteen pre-arranged decks there were, for each player: two strong hands, two weak
hands and two weak hands for which the players were to bluff. The dependent variables selected
were chosen to measure both overt and covert effects of bluffing. These included number of eye
blinks, hand gestures, mean heart rate (HR) and mean skin conductance levels (SCL).
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 5
Although no significant findings were obtained for the eye blink or hand gesture
variables, there were two significant effects for HR and SCL. During the first recording epoch,
HR was significantly higher for bluff and win hands than for fold hands. During the second
epoch, SCLs were significantly higher for bluff hands over strong hands, as well as strong hands
over fold hands. Lee and Dixon interpreted these data as an interplay between cognitive load and
arousal. They hypothesized that the initial increases in HR for strong and bluff hands, during the
first epoch, mostly reflected an increase in cognitive load. That is, participants mentally worked
to acquaint themselves with game play in a novel environment (in the lab, with electrodes
affixed) and more importantly, worked to decide how much to bet in order to maximize their
chances of winning. Lee and Dixon hypothesized that, together, these demands amounted to a
partial depletion of the participants’ cognitive resources during the first epoch. This would have
precluded the participants from actively engaging in the deception required in bluffing and thus
explained the negligible increases in arousal (as measured by SCL) during epoch one. During the
second epoch, having been acclimatized to game play, the players would have had sufficient
cognitive resources available to actively engage in deception. This would explain the elevated
SCL during the bluff hands in the second epoch.
One potential criticism of the Lee and Dixon study was the exclusive reliance on
psychophysical measures to assess arousal. Their hypotheses concerning arousal, cognitive load,
and how these factors interact with hand type would have been strengthened had subjective
measures of arousal supplemented the objective measures.
The current study has three purposes: replication of the previous study, adding subjective
measures of arousal to complement psychophysical measures of arousal, and a specific
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 6
investigation of the effects of cognitive load on poker gameplay. To more closely examine
cognitive load we will be making two additions to Lee and Dixon’s experimental design: a
subjective rating of arousal and a baseline-mental arithmetic task utilizing heart rate variability
(HRV). To compare the participant’s subjective feelings of arousal with objective measurements
of cognitive load we will use a 9-point Likert-type visual analogue scale (VAS; Morris, 1995). To
analyze their theory on the interaction of cognitive load and poker gameplay we will also have
the participants complete a baseline-mental arithmetic task. Specifically the serial sevens
subtraction task (Pennington, 1947; Smith, 1967; Frigy, Varga, Orbán, & Incze, 2005). For this
task we will utilize HRV measures as it has been suggested they are an accurate indicator of
cognitive load (Gunther Moor, Crone, & van der Molen, 2010; Verkuil, Brosschot, Borkovec, &
Thayer, 2009). HR differs from HRV in its composition. As opposed to measuring the mean rate
at which the heart beats, HRV is a number of statistical processes performed on a series of inter-
heartbeat intervals recorded over an epoch of interest (Clifford, 2002).
Overall, we intend to measure cognitive load and arousal in volunteer participants as they
play Texas Hold ‘em poker. During gameplay, we expect cognitive load to be higher during the
first epoch than during the second. We predict these maximal levels of cognitive load will
abolish any arousal responses to the differing hand types, indicated by indifferent SCL responses.
In the second epoch, after the participants become familiar with the game, HR will decrease for
bluffing and strong hands (becoming equivalent to fold hands), but SCL will now differentiate
the hand types: bluff hands will have the highest SCLs, strong hands next highest, and fold hands
the least.
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 7
Methodology
Design
Our study was a two-factor, repeated-measures design. The first factor was type of hand
(strong hand, weak hand, bluff hand). The second factor was epoch (the first iteration during
which a participant received each of the three hands and the second iteration). In addition we
recorded a baseline and a mental arithmetic task for each participant.
Procedure
After entering the testing facility and completing informed consent procedures
participants were asked to wash their hands prior to electrode attachment. Gender-matched
research assistants applied the five experimental electrodes. Three participants were seated at a
mock Texas Hold ‘em gameplay table facing a dealer (a research assistant). After a ten-minute
acclimatization period a 60s baseline epoch was recorded. Following this, participants completed
a mental arithmetic task for 60s. The task was the serial sevens subtraction task in which
participants, beginning at the number 100, silently count backwards by sevens (Smith, 1967).
Following the baseline and mental arithmetic tasks, the dealer administered specific poker
instructions (rules of the game). They were also told that when they saw specific card
combinations they were to bluff. To ensure players understood the instructions the dealer then
dealt two “face-up” rounds of poker, explaining each round and suggesting the best course of
action to each player. Participants were informed that each would receive a prize (chips, candy
bars) commensurate with the amount of playing chips they had at the conclusion of the
experiment. After verbally ensuring each player was comfortable with the rules and general
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 8
gameplay the eighteen experimental rounds of poker began. These eighteen rounds were played
in a randomized order, selected before the experiment commenced.
Participants
Research participants were 39 University of Waterloo students (24 male, Mage = 20.6
years, age range: 19-25 years), completing the experiment in return for course credit. To be
eligible for the experiment participants must have been: 1) between the age of 19 and 65 (the
former being the legal age for gambling in the province of Ontario); 2) not currently taking any
anxiety reducing medication (as this would interfere with psychophysical measures); and 3) not
currently be in treatment for problem gambling.
Measures
A visual analogue scale (VAS) was used to allow participants to record their subjective
ratings of arousal. At the conclusion of each hand, participants confidentially indicated on a 9-
point Likert scale how physiologically aroused they felt during the last round of gameplay. A
score of one corresponded to “Not at all aroused” and nine to “Very physiologically aroused”.
The VAS scale uses images of a cartoon character to depict varying levels of arousal in the case a
participant is not familiar with the concept of physiologic arousal (Morris, 1995; see Appendix
1).
Skin conductance levels (SCL) were used to measure the participants’ objective levels
of arousal during strong, weak and bluffing hands. To minimize the effect of baseline drift over
time we used delta SCLs. The participant’s skin conductance rate (measured in microsieverts;
µSv) at the beginning of the epoch of interest was subtracted from the highest maxima achieved
throughout the epoch.
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 9
Heart rate (HR) data were used to measure the participants’ levels of cognitive load.
Mean beats per minute (bpm) were calculated from an average of interbeat intervals, producing a
mean instantaneous heart rate (HRi) for each epoch of interest.
Heart rate variability (HRV) data were used to assess Lee and Dixon’s contention that
increased levels of cognitive load lead to their unexpected results (increased HR in epoch one for
strong and bluff hands, without any effect on SCL). HRV data consist of various statistical
operations performed on a series of interbeat intervals, recorded over an epoch of specific length
(Task Force of the European Society of Cardiologists, 1996). Given the ultra-short duration of
our recording epochs (60s) we limited our HRV analysis to time-domain measures. The current
consensus of the literature is that frequency-domain analysis of epochs of less than five minutes
duration is ill-advised as the data are too susceptible to artifact. We used three redundant
measures, as the current recommendations are to use two or more when performing HRV
analysis within a psychophysiological study (Clifford, 2002). We selected the three most popular
time-domain measures: SDNN, NN50 and RMSSD. As opposed to increasing in response to
increased cognitive load (as HR does), HRV decreases. This signals a reduction in the variability
of the interbeat intervals. Heartbeats deemed to be artifact in nature were not included in these
analyses.
SDNN is the standard deviation, of the intervals between each pair of adjacent normal
heartbeats (all non-artifact, non-ectopic R-R intervals).
NN50 is the number of successive, normal, interbeat intervals which differ by more than
50 ms. This range is somewhat arbitrarily selected and is used as another indicator of the
variability of the heart rate over an epoch of interest.
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 10
RMSSD is a rather complicated statistical operation: the root, of the mean, of the square,
of the standard deviations, of all of the intervals between normal heartbeats over an epoch of
interest.
Apparatus
SCL, HR and HRV information were acquired through an eight-channel AD Instruments
Powerlab (model 8/30; Powerlab; Colorado Springs, CO, USA). SCL data were collected via two
velcro-electrodes placed at the distal phalanges of the index and ring fingers of the participant’s
non-dominant hand. HR and HRV data were collected from three self-adhesive electrodes placed
on the participant’s skin in a modified Mason-Likar arrangement (Mason & Likar, 1966; see
Appendix 2). This arrangement places two electrodes in the infraclavicular fossae, 2cm medial to
the deltoid border. A third electrode, acting as an earth ground, is placed on the abdomen in the
left anterior axillary line, 3-4 cm superior to the iliac crest. The Mason-Likar arrangement
considerably reduces movement artifact from skeletal muscle allowing the participants to move
more freely during gameplay, an otherwise considerable challenge to the ecological validity of
the study.
Data files were analyzed in LabChart Version 7.2.3 on a MacBook laptop. Exclusions
were set with a macro to analyze only the twenty 60s epochs of interest (baseline, mental
arithmetic and eighteen poker hands) for each participant. As HRV analysis cannot be conducted
on epochs of unequal lengths (Clifford, 2002) any quickly played poker hands resulting in an
epoch of less than 60s were excluded. A digital bandpass filter was applied to the data signal with
frequencies individually selected to optimize the signal-to-noise ratio of R-waves to other cardiac
waveforms. All variables were outlier-corrected to within 2.5 standard deviations of their mean.
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 11
Results
Data Attrition
Unfortunately, given the complexity of the experiment, a considerable portion of
experimental epochs were lost. As players engaged in poker gameplay (reaching across the table
to pick up cards or place their bets) movement artifact rendered some epochs completely
unanalyzable. Compounding these losses is the aforementioned criteria that all HRV epochs to be
compared must be of equal duration. Taken together these factors caused the sample size to be as
low as 20 cases in some of the dependent variables (detailed specifically in the ensuing tables).
Arousal and Cognitive Load
As summarized in Table 1.
Table 1Arousal and Cognitive Load
VAS (n=33)VAS (n=33) Δ SCL (n=24)Δ SCL (n=24) HR (n=34)HR (n=34)
Type of Hand Mean SD Mean SD Mean SD
First EpochFirst EpochFirst EpochFirst Epoch
Strong 6.58 1.275 2.72 2.226 82.75 10.835
Weak 3.36 1.558 1.483 1.532 80.52 11.274
Bluff 5.82 1.811 2.603 1.187 85.60 10.789
Second EpochSecond EpochSecond EpochSecond Epoch
Strong 5.73 1.275 2.41 1.768 83.81 10.821
Weak 3.45 2.181 1.548 1.152 80.31 11.478
Bluff 5.00 2.107 1.960 1.587 81.55 9.011
Note: VAS was based on a 9-point Likert scale, Δ SCL measured in µSv, HR measured in mean bpm.
VAS had a main effect of type of hand, F(2,64) = 39.761, MSE = 3.340, p<.000, n2 =
0.554. In addition, there was a main effect of epoch order, F(1, 32) = 6.013, MSE = 2.271, p<.02,
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 12
n2 = 0.158. The type of hand by epoch order interaction was not significant, F(2, 64) = 1.866,
MSE = 2.52, p<n.s.. To further understand the type of hand main effect we conducted
Bonferroni-corrected pairwise comparisons. Participant’s subjective ratings of their arousal
during strong hands (M=6.342) were significantly higher than during both bluff hands
(M=5.434), t(75) = 3.543, SEM = 0.256, p<.001, and weak hands (M=3.533), t(76) = 10.694,
SEM = .266, p<.000. As well, bluff hands were significantly higher than weak hands, t(75) =
6.182, SEM = .302, p<.000.
SCL had a main effect of type of hand, F(2,46) = 6.775, MSE = 2.078, p<.003, n2 =
0.228. Neither the epoch order, F(1, 23) = 1.175, MSE = 2.692, p<.n.s., nor the type of hand by
epoch order interaction, F(2, 46) = 0.841, MSE = 1.797, p<n.s., were significant. Bonferroni-
corrected pairwise comparisons conducted on type of hand revealed participant’s objective
arousal levels during strong hands (M=2.562) were significantly higher than during weak hands
(M=1.515) t(47) = 20.907, SEM = .343, p<.017. Bluff hands (M=2.281) were significantly higher
than weak hands as well, t(47) = 30.008, SEM = .175, p<.001. Bluff and strong hands were not
significantly different, t(47) = 5.747, SEM = 0.334, p<n.s..
HR had a main effect of type of hand F(2,66) = 8.175, MSE = 25.327, p<.001, n2 =
0.199. In addition, there was a main effect of the type of hand by epoch order interaction, F(2,
18) = 6.091, MSE = 19.725, p<.004, n2 = 0.156. Epoch order was not significant, F(1, 33) =
1.951, MSE = 29.592, p<.n.s. Bonferroni-corrected pairwise comparisons of the main effect of
type of hand indicated that participant’s heart rates during strong hands (M=83.278) were
significantly higher than during weak hands (M=80.413), t(67) = 24.764, SEM = 0.947, p<.014.
Bluff hands (M=83.572) were significantly higher than weak hands as well, t(67) = 32.403, SEM
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 13
= 0.798, p<.001. Strong and bluff hands were not significantly different, t(67) = 2.872, SEM =
0.838, p<.n.s.. To unpack the type of hand by epoch order interaction, we conducted simple
main effects comparisons to analyze the two epochs separately. Bonferroni-corrected pairwise
comparisons indicated that, in epoch one, bluff hands (M=85.594) lead to significantly higher
heart rates than strong hands (M=82.741), t(33) = 2.61, SEM = 1.092, p<.014, and than weak
hands (M=80.518), t(33) = 3.99, SEM = 1.271, p<.000. In epoch two, strong hands (M=83.809)
lead to higher heart rates than weak hands (M=80.309), t(33) = 2.7, SEM = 1.294, p<.011. Bluff
hands (M=81.549) were not significantly higher than weak hands in the second epoch t(33) =
1.27, SEM = 0.977, p<n.s..
Baseline-Mental Arithmetic task
As shown in Table 2, skin conductance levels were not significantly different between the
resting baseline condition and the mental arithmetic task. As previously noted, HRV has been
used to track cognitive load. Of the three HRV variables only SDNN significantly responded to
the increases in cognitive load brought on by the mental arithmetic task, t(37) = 2.948, SEM =
2.403, p<.006. As such this measure was used to address whether there was a preferential
increase in cognitive load during the first epoch of the poker task.
Table 2Four variable analysis of the Baseline-Mental Arithmetic task
Δ SCLΔ SCL SDNNSDNN NN50NN50 RMSSDRMSSD
Mean SD Mean SD Mean SD Mean SD
Baseline 0.759 1.167 52.986 16.035 13.3 9.17 47.476 24.593
Mental Arithmetic 1.055 1.853 45.902 14.077 11.5 9.61 42.561 26.511
Difference 0.296 -7.084*-7.084* -1.8 -4.915
Note: Δ SCL measured in µSv, SDNN and RMSSD measured in ms, NN50 is simple occurrence count; SCL N=39, SDNN, NN50 and RMSSD N=38; * p<.006; SCL, NN50 & RMSSD p< n.s.
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 14
As shown in Table 3, SDNN showed neither a main effect of type of hand, F(2, 38) =
0.218, MSE = 100.549, p<.n.s., epoch order, F(1, 19) = 1.414, MSE = 54.719, p<.n.s., or a type
of hand by epoch order interaction, F(2, 38) = 0.399, MSE = 53.217, p<.n.s.
Table 3Arousal and Cognitive Load with HRV
VAS (n=33)VAS (n=33) Δ SCL (n=24)Δ SCL (n=24) SDNN (n=20)SDNN (n=20)
Type of Hand Mean SD Mean SD Mean SD
First EpochFirst EpochFirst EpochFirst Epoch
Strong 6.58 1.275 2.72 2.226 51.034 12.840
Weak 3.36 1.558 1.483 1.532 50.819 13.841
Bluff 5.82 1.811 2.603 1.187 50.320 11.903
Second EpochSecond EpochSecond EpochSecond Epoch
Strong 5.73 1.275 2.41 1.768 48.040 11.872
Weak 3.45 2.181 1.548 1.152 50.731 12.547
Bluff 5.00 2.107 1.960 1.587 48.583 9.695
Note: VAS was based on a 9-point Likert scale, Δ SCL measured in µSv, SDNN measured in ms.
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 15
Discussion
The current study had three purposes: replication of the previous study, adding subjective
measures of arousal to complement psychophysical measures of arousal and a specific
investigation of the effects of cognitive load on poker gameplay.
Replication
For SCL measures, Lee and Dixon found that bluffing led to higher SCL levels than
either strong or weak hands but this effect only occurred during epoch two. In our study, during
epoch one, strong and bluff hands led to significantly higher SCL levels than during weak hands.
For HR measures, Lee and Dixon found significantly higher heart rates for bluffing and strong
hands in epoch one but not in epoch two. In our study, bluffing led to higher HR, than either
strong or weak hands, during epoch one. Yet during epoch two, only strong hands lead to higher
heart rates than weak hands.
Subjective measures of arousal
Our study added a subjective measure of arousal using VAS. We found that participants’
subjective ratings of arousal were highest for strong hands when compared with both bluff and
weak hands. As well their subjective ratings of arousal were higher for bluff hands than for weak
hands.
Measuring cognitive load using HRV
When baseline resting HRV was contrasted with an epoch during which participants
engaged in a task known to increase cognitive load, all three measures of HRV showed nominal
reductions in the predicted direction. However, only SDNN showed a significant response to
cognitive load. As such, with these participants, SDNN was able to strongly track increases in
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 16
cognitive load. After determining that SDNN was best suited for this analysis we examined the
type of hand and epoch order factors alongside VAS, delta SCL and mean HR. Although SDNN
reacted sharply to the mental arithmetic task there were no significant differences between
strong, weak or bluff hands. If Lee and Dixon were correct in their contention that cognitive load
increases elevated HR during bluffing and strong hands (and somehow masked SCL effects),
then we should have shown significant reductions in SDNN during bluffing and strong hands in
epoch one. However, no such effects were noted.
These data suggest that the large increases in HR during the bluff hands were not due to
increased cognitive load. By contrast, it appears that the deception and/or risk involved in
bluffing served to elevate HR. When a player bluffs, they are holding a weak hand yet proceed as
if they are playing from a position of strength. To win, the player must successfully masquerade
as if they were holding a strong hand whilst under the direct scrutiny of the other players. In
addition, there is considerable risk involved in bluffing, as players continue to bet with a hand
that may be substantially inferior to their opponents’. Outside of the gambling literature there
exists strong support for the links between deception and arousal (DeTurck & Miller, 1985;
Gödert, Rill, & Vossel, 2001) as well as between risk and arousal (Critchley, Mathias, & Dolan,
2001).
Unlike the study of Lee and Dixon, we found converging effects for HR and SCL
measures. Most importantly for both HR and SCL, significantly larger effects were noted when
players attempted to bluff with weak hands compared to when they were simply going to fold a
weak hand. We propose that this elevated state of arousal for bluffing may be one of the key
features which makes this form of poker particularly arousing.
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 17
In our study the subjective ratings of arousal were highest for strong hands, followed by
bluffing hands, and weakest for fold hands. The literature on arousal and risk led us to predict
that bluffing would lead to more subjective arousal than strong hands because of the increased
risk. In our experiment, players were forced to bluff on specific hands. By removing the choice
of when and when not to bluff, we may have reduced arousal in this condition. Importantly for
both subjective and psychophysiological measures of arousal, bluffing on a weak hand was
significantly more arousing than folding on a weak hand.
As afore mentioned, little is currently understood about the mechanisms underlying the
allure and addictive potentially of Texas Hold ‘em poker. There is much evidence to suggest that
the mechanisms involved in the attraction and addiction of other gambling mediums is arousal.
Blaszczynski and Nower (2002) cite arousal as the reinforcement process behind problem
gambling (Blaszczynski & Nower, 2002). Our data suggest that arousal features prominently
throughout poker. Beyond the excitement one would intuitively associate with playing a strong
hand to win there is the thrill involved with bluffing. These are weak hands which, without the
concept of bluffing, a player would simply toss aside with minimal arousal. Bluffing provides a
mechanism whereby even weak hands can be highly arousing. When one bluffs and wins, such
arousal could be highly reinforcing.
A recurring challenge within gambling research is ecological validity. Both the previous
study (Lee and Dixon) as well as the current study went to great pains to preserve what
authenticity is available within an experiment conducted on undergraduates within the confines
of a psychology research lab. We purchased a Texas Hold ‘em mat screened with similar
markings to those found in casinos and on televised poker tournaments. We utilized actual
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 18
gameplay chips and rewarded the participants, beyond their course credit, commensurate with
their performance. Despite these measures we would be interested to study arousal and cognitive
load in Texas Hold ‘em under even more realistic conditions. Although our participants were
unaware that the decks were pre-arranged, or that there were multiple decks at all (the dealer
concealed the swap of pre-sorted decks while shuffling), this is still far from the completely
randomized nature of normal poker gameplay. Complete randomization might be possible if one
could devise an apparatus to have each participant confidentially indicate whether their
intentions with the current hand were to play to win from a position of strength, to fold a weak
hand or to play a weak hand to win (to bluff). As well, although we endeavored to ensure at least
a baseline competency in gameplay before the experimental rounds began, it would be
interesting to quantify the participant’s skill in poker and analyze statistically whether this had a
significant effect on physiologic spectra.
If much of the revenue and addiction of the gambling world are predicated on generating
physiologic arousal then Texas Hold ‘em poker is a prime candidate. The proportion of time a
player’s arousal levels are elevated during gameplay is exaggerated thanks to bluffing. As well,
given the simple nature and design of the game, there is relatively little “downtime” in Texas
Hold ‘em. This is especially the case in on-line versions of the game, where a player can play at
multiple tables at once. This means the mind and body of a poker player is subjected to constant
stimuli and cues which increase arousal over the course of their play. As our understanding of the
game continues to improve it is entirely possible that policy change will be required to protect
future generations of poker players developing gambling problems to this potentially highly
addictive game.
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 19
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AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 22
Appendices
Appendix 1: VAS
Adapted from: Morris, J. (1995). Observations: SAM: The self-assessment manikin.
Appendix 2: Mason-Likar electrode placement
Adapted from: Malmivuo, J., & Plonsey, R. (1995). Bioelectromagnetism
AROUSAL AND COGNITIVE LOAD IN TEXAS HOLD EM POKER 23
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