Luke Clark: Professor at Department of Psychology, UBC Faculty of Arts

Professor

Faculty of Arts

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Great Supervisor Week Mentions

Each year graduate students are encouraged to give kudos to their supervisors through social media and our website as part of #GreatSupervisorWeek. Below are students who mentioned this supervisor since the initiative was started in 2017.

Last year, on Supervisor Appreciation Day, we dedicated our waiting area to @LukeClark01. This year, we re-dedicated it. We're so proud, we made mugs. Every grad student in the lab bought one. #GreatSupervisor #UBC

Spencer Murch (2019)

Well @LukeClark01, another Supervisor Appreciation Week is upon us. Without being overly cloying, here are 3 things I really like about working for you. #greatsupervisor #UBC

1. You put a huge amount of work into editing and improving our writing. Sorry I took 5 years to learn the difference between 'While' and 'Although.'

2. At least 3 or 4 times a year, you keep me from doing (or tweeting!) something that would seriously impact my career.

3. Your (almost encyclopedic) knowledge of papers (and authors... and journals...) is so impressive that I sometimes try to figure out exactly how you do it. Thanks, Luke!

Spencer Murch (2019)

A #GreatSupervisor deserves thanks, but an awesome supervisor deserves pranks. @LukeClark01, the lab thanks you for your effort. #ubc

Spencer Murch (2018)

Graduate Student Supervision

Doctoral Student Supervision

Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.

Chasing in online gambling and its practical application in gambling intervention (2023)

'Chasing' refers to a tendency to increase betting in an effort to recoup prior losses (i.e., 'loss chasing') or to satisfy an increased gambling desire following wins (i.e., 'win chasing'). Chasing characterizes the transition from recreational to problem gambling, but few studies have examined this behaviour systematically. Using online gambling data, I sought a holistic understanding of chasing by capturing between- and within-session chasing behaviour. Further, I evaluated a behavioural intervention to reduce loss chasing. Chapters 2, 3, and 4 examined between- and within-session chasing using naturalistic data from a gambling website (PlayNow.com in British Columbia, Canada). For between-session chasing, average gamblers returned more slowly after a losing session and returned more quickly after a winning session. Within-session chasing depends on game type, chasing measurement (bet amount vs. quit probability), and outcome timeframe (immediate vs. cumulative outcomes). Across most games, loss chasing depended more on timeframe but not measurement, whereas win chasing depended more on measurement. After losing more on the last bet, gamblers staked larger amounts over a longer session, but when cumulative losses mounted, gamblers staked smaller amounts over a shorter session. After winning more, gamblers bet more over a shorter session. Chapter 4 used enrolment in the Voluntary Self-Exclusion (VSE) program as a proxy for likely gambling problems. While conventional assessments of gambling problems focus on between-session loss chasing, it did not differentiate VSE gamblers from Non-VSE gamblers. Instead, these groups differed in their within-session loss chasing tendencies. Therefore, future research aiming to identify high-risk gambling patterns should also consider within-session behavioural markers. Chapter 5 recruited gamblers from the survey platform, Prolific, and examined the effectiveness of a novel ‘cashing out’ procedure in alleviating loss chasing. In non-problem gamblers, the cashing out manipulation significantly lowered the amount wagered, aligned with the realization effect. There was no interaction between the cashing-out condition and the gambling group, although the cashing-out procedure was not statistically significant in the at-risk or problem gambling groups. These findings provide future directions for identifying gambling problems based on behavioural tracking data, and present proof of concept data for a new digital harm reduction tool.

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Gambling-related cognitive distortions : their associations, measurement, and utility to assess gamblification in video games (2023)

Gambling-related cognitive distortions (GRCDs) are central to the cognitive model of gambling, and through these lenses, gamblers may perceive themselves as being able to predict or influence randomly determined outcomes. Chapter 2 explored the associations between schizotypy, GRCDs, and problematic gambling via three cross-sectional samples. Schizotypal personality (schizotypy) is a cluster of traits in the general population, including alterations in belief formation that may underpin delusional thinking. Small-to-moderate associations were detected between components of schizotypy and gambling-related variables, pointing to shared biases relating to belief formation and decision-making. Chapter 3 sought to develop a scale to assess state-activated GRCDs during slot machine gambling. Scale items were developed and refined across three samples and underwent exploratory factor analysis. This produced a 17-item scale comprising 4 factors: Magical Thinking, Personal Illusion of Control, Hot Hand Fallacy, and Experienced Luck. Initial reliability and validity was established. This instrument increases accessibility to state-activated gambling beliefs. Chapters 4 & 5 focused upon the gamblification of video games by investigating ‘loot boxes’, virtual items in video games that generate a randomized in-game reward of varying desirability. Chapter 4 was among the first studies to establish a cross-sectional link between loot boxes and gambling. Loot boxes were perceived as gambling by a majority of participants. Loot box expenditure, and their risky use, was moderately linked to GRCDs and problematic gambling. The gambling-related variables were also a stronger predictor of risky loot box use than a measure of disordered gaming. These results underline a psychological similarity between loot boxes and gambling and implicate each behaviour as a risk factor for the other, although these cross-sectional data do not establish directionality. Chapter 5 clarified the directional relationship between loot boxes and gambling behaviour, via a longitudinal study. In a sample of non-gamblers, ‘migration’ to gambling was predicted by loot box expenditure and risky use six months later, whereas non-loot box microtransaction expenditure did not. In an exploratory resorting of participants, baseline GRCD endorsement also predicted migration to loot box use. These results are consistent with a bi-directional temporal relationship and support regulatory action on loot boxes.

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Behavioural and physiological correlates of immersion in gambling using electronic gaming machines (2020)

More than most gambling forms, Electronic Gaming Machines (EGMs, e.g. modern slot machines) have been linked to Gambling Disorder, a behavioural addiction recognized by the American Psychiatric Association. Immersion is a ‘trance-like’ state of extreme focus often reported in EGM gambling. Immersion in EGM gambling is a robust predictor of gambling problems, but is poorly understood. Few studies have investigated the cognitive, behavioural, and physiological correlates of this subjective state, and existing data rely on retrospective self-report. I investigated these topics, hypothesizing that immersion in EGM gambling produces measurable shifts in behaviour and physiological arousal, and that EGM immersion affects gamblers’ behaviour towards specific elements of the device.The first two experiments recruited samples of undergraduate students, and examined whether self-reported immersion during an EGM gambling session correlated with cardiac markers of sympathetic and parasympathetic nervous system activity. EGM gambling saw decreased parasympathetic nervous system activity irrespective of immersion. Changes in sympathetic activity were limited to the first few minutes of gambling, and were specifically associated with immersion. Additionally, higher rates of immersion were found when participants placed bets across multiple paylines, a feature endemic to modern EGMs.The third and fourth experiments recruited a sample of experienced EGM gamblers, who gambled on a real EGM while providing high-resolution eye tracking data. Immersion levels were associated with increased time spent looking at the EGM’s credit window, and decreased time on its spinning reels. Immersion was positively associated with the number of saccades participants made while gambling, as well as longer post-reinforcement pauses, a behavioural indicator of perceived reward value. We found that the EGM’s free spin bonus feature was associated with significant increases in pupil diameter, potentially indicating sympathetic nervous system arousal.Together, these experiments suggest that immersion is an active state characterized by increased reward-seeking. These data further link immersion to activity within the sympathetic nervous system, and show that immersion is impacted by specific features of modern EGMs. These results present novel candidate markers of immersion, both behavioural and physiological, and provide insight into the disproportionate rates of gambling problems associated with modern EGMs.

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Master's Student Supervision

Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.

Impulse and reason : justifications in problem gambling (2023)

Impulsivity is a core component of problem gambling. This conventionally entails acting without thinking. However, people may use deliberate, intentional justifications to grant themselves permission to gamble. Across 3 studies, I examined the degree to which gambling justifications were associated with problem gambling severity and gambling behaviour. Participants were gamblers who had experience with, or were currently, trying to reduce their gambling. In Studies 1 and 2, participants reported their gambling justifications and completed standard measures of impulsivity, cognitive distortions, and problem gambling severity. I found that justifications were positively associated with problem gambling severity even after controlling for impulsivity and cognitive distortions. These results were replicated in Study 2 with an improved design. In Study 3, I used a daily diary approach to examine fluctuations in justifications, craving, positive and negative affect, and gambling behaviour over a 21-day window. Results showed that justifications were positively, albeit modestly, associated with next-day gambling even after controlling for craving, positive affect, and negative affect. These findings indicate that justifications are a neglected aspect of cognition in gamblers that cannot be explained by impulsivity, cognitive distortions, craving, or affect, and may contribute to self-control failures and thus recovery from problem gambling.

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The near-miss effect in online slot-machine gambling: a series of conceptual replications (2022)

The field of gambling studies is beginning to recognize the need to conduct targeted replications of influential effects throughout the field. Given the limited resources afforded to researchers, we must be systematic in our approach to selecting which effects are most in need of replication. Following a systematic approach to replication selection, a series of conceptual replications of the ‘near-miss effect’ in slot machine gambling was conducted, on online community samples. Near-miss outcomes on a slot machine are those that appear proximal to a win, though they are functionally identical to other losing outcomes (herein termed ‘full misses’). Near-misses have been shown to elicit a range of differential psychological effects compared to full-misses. Experiment 1a and 1b attempted to replicate a previous study by Clark et al. 2009 that 1) near-misses are experienced as more negative, 2) near-misses are rated as more motivating to continue playing a slot machine. Experiment 2 tested the effects on speed of gambling (a replication of Dixon et al. 2013) that near-miss outcomes speed up participant speed of play compared to full miss outcomes. Experiment 3 tested whether near-miss outcomes influence subsequent bet size. I replicated the motivation hypothesis of Clark et el., (2009), but found a significant effect in the opposite direction for the valence hypothesis. Across both study 1a and 1b, near-miss outcomes were more positive relative to full-misses. Experiment 2 replicated the hypothesis that near-miss outcomes increase speed of play (Dixon et al., 2013). Experiment 3 observed near-miss outcomes led to a significant increase in bet size on the subsequent spin relative to full-miss outcomes. I consider how this pattern of results across 3 different dependent variables speak to the different theoretical accounts of how near-misses operate.

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The severity of gambling problem and loss aversion in healthy gamblers: the implications of Prospect Theory in gambling research (2018)

Gambling decisions are inherently risky decisions involving wins and losses. The severity of gambling problems varies with the persistence of betting despite mounting losses. ‘Prospect Theory’, a descriptive model of risky decision-making from the field of behavioural economics, describes an influential phenomenon called Loss Aversion: the natural tendency for “losses to loom larger than gains” when people evaluate risky choices (Kahneman and Tversky, 1992). It is an intuitive prediction that people with the more severe gambling problem will display systematic alterations in their loss aversion. Experiment 1 reviewed two widely-used loss aversion tasks (the ‘matrix’ and ‘staircase’ methods) in the past studies, which also have varied in whether trial-by-trial outcome feedback was presented within each task. Hence, Experiment 1 was a methodological study. It aimed to evaluate whether the presentation of outcome feedback influences loss aversion scores with student samples, as a precursor for Experiment 2 using this procedure in regular gamblers. Experiment 2 recruited non-problem gamblers with varying levels of sub-clinical gambling problems. With the established task, it studied the relationships between the severity of gambling problems and risk preferences including risk attitudes across the gain and loss domains, loss aversion, and probability distortions. In Experiment 1, the outcome feedback did not show significant influence on the level of loss aversion. In Experiment 2, the findings indicated that the risk attitudes in the gain domain were the only Prospect Theory-based variable that correlated with the severity of gambling problems; participants with more severe problems tended to be more risk-seeking in the gain domain, and in the loss domain, all participants displayed ambivalent choices between risk-seeking and risk-averse. Moreover, the level of loss aversion and the magnitudes of probability distortions for potential gains and losses did not correlate with the severity of gambling problems.

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Slot machine gambling and testosterone: evidence for a 'winner-loser' effect? (2017)

Testosterone can be seen to modulate cognition and behaviour in many ways. One likely effect is to promote risky decision-making. According to a phenomenon termed the “winner-loser effect,” testosterone has also been observed to fluctuate in response to winning or losing competitions with others, with wins causing increases and losses causing decreases. Surprisingly, few studies have investigated the effects of gambling on testosterone levels, or whether individual differences in testosterone are related to risky gambling strategies. More specifically, the winner-loser effect may extend to slot machine gambling as a solitary gambling activity if players tend to ‘anthropomorphize’ slot machines, i.e. to treat the machine as a human agent with intentions and feelings. This study used a quasi-experimental design to measure testosterone fluctuations in response to winning and losing during a period of authentic slot machine gambling. Cortisol and anthropomorphism were investigated as potential moderators of a winner-loser effect on testosterone. Male participants (n = 120) provided saliva samples before and after a period of gambling on an authentic slot machine. Participants also provided measures of real-world gambling involvement, subjective experiences during slot machine play, and anthropomorphic tendencies. Contrary to predictions, winning and losing were not significantly associated with divergent effects on testosterone, even after considering cortisol levels and anthropomorphization of the slot machine. An exploratory analysis supported a link between positive affect (higher in winners) and decreases in testosterone, which suggested that the winner-loser effect may be reversed in slot machine gambling. In addition, baseline testosterone predicted a slower rate of gambling. The results of this study add to a growing literature on the boundary conditions of the winner-loser effect, which inform future examinations of the role of testosterone in gambling behaviour.

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