Slot machines are an extremely popular form of gambling, offering immediate feedback and varied rewards. In this study, we investigated two distinct pathways through which players might experience enjoyment while playing slots. One pathway focuses on how strongly a player reacts to rewards. The other pathway examines what we term dark flow—a pleasurable yet potentially maladaptive state characterized by complete absorption in slots play that offers an escape from negative, depression-related thoughts.
A total of 129 frequent slot-machine players (76 males, 53 females) were recruited and assessed in the lobby of a casino. All participants were at least 19 years old (the legal age to gamble on slots in Ontario, Canada), played slot machines at least once per week, and were not undergoing treatment for problem gambling. During the study, they played on slot-machine simulators that tracked both behavioral and subjective responses.
To evaluate how participants reacted to slot-machine rewards:
Post-Reinforcement Pauses (PRPs)
PRPs measure the time gap between the revelation of an outcome (win or loss) and the initiation of the next spin. Previous research (e.g., Dixon, MacLaren, Jarick, Fugelsang, & Harrigan, 2012) shows that PRPs are typically longer after wins. In this study, the slope of PRP length across varying win sizes was calculated for each participant to determine how strongly they reacted to increasing rewards.
Spin-Button Force
A force transducer placed under the spin button recorded how hard participants pressed after each slot-machine outcome. As with PRPs, the slope of force across differing win magnitudes was used to quantify reward reactivity.
Slots Game Enjoyment
Enjoyment was assessed through the positive affect subscale of the Game Experiences Questionnaire (GEQ; IJsselsteijn, de Kort, Poels, Jurgelionis, & Bellotti, 2007). Participants rated items such as “I felt happy” or “I enjoyed it,” indicating the degree to which they derived pleasure from the playing session.
Dark Flow
The flow dimension of the GEQ measured absorption in the game, using items like “I forgot everything around me” and “I lost connection with the outside world.” High scores indicated a deep, potentially escapist immersion in the gameplay, referred to as dark flow (Dixon, Stange, et al., 2017).
Problem Gambling and Depression
Participants completed the Problem Gambling Severity Index (PGSI; Ferris & Wynne, 2001) and the depression subscale of the Depression, Anxiety, and Stress Scale (DASS-21; Lovibond & Lovibond, 1995). These instruments assessed gambling-related issues and symptoms of depression.
Participants played a 5-reel, 20-line slot-machine simulator for 301 spins. This simulator mimicked commercial slot machines, including celebratory audio-visual feedback for wins and “Losses Disguised as Wins” (LDWs). Thought probes were interspersed at regular intervals (every 50 spins) to gauge the participant’s focus and affect in the moment. After completing the slot-machine session, participants filled out questionnaires on enjoyment (GEQ), depression (DASS-21), and problem gambling (PGSI). Compensation included a $25 gift card plus any winnings, rounded to $10.
Analyses showed that both PRPs and spin-button force correlated significantly with participants’ reported enjoyment of the slots session. In other words, those who paused longer or pressed the spin button harder following larger wins tended to rate their experience as more enjoyable overall.
Neither PRPs nor spin-button force correlated with measures of problem gambling (PGSI) or depression (DASS-21). These findings suggest that purely enjoying the excitement of winning does not necessarily indicate problematic gambling behavior or underlying depressive symptoms.
Participants who reported higher levels of dark flow also indicated stronger enjoyment during the slots session—often surpassing the enjoyment explained by reward reactivity alone. However, dark flow was positively correlated with both problem gambling scores and depression. This correlation implies that while dark flow may be pleasurable in the moment (by providing an escape from negative thoughts), it can coincide with or reinforce risky gambling habits and depressive tendencies.
Our results highlight two distinct pathways to enjoyment in slot-machine play:
Reward Reactivity (the “Light” Pathway)
Players who react strongly to wins—evidenced by longer PRPs and greater spin-button force—tend to find slot machines entertaining because they relish the excitement and reinforcement of wins. This pathway appears less tied to problem gambling or depression.
Dark Flow (the “Dark” Pathway)
A subset of players reported high absorption in the game, losing track of time and the outside world. Though this heightened immersion can enhance enjoyment, it also correlates with both gambling-related problems and depressive symptoms, suggesting a potentially harmful cycle of escapism.
These findings underscore the importance of distinguishing between these two enjoyment mechanisms. While reacting positively to wins is not inherently problematic, seeking the intense immersive state of dark flow can lead to negative outcomes, particularly for those with underlying depressive tendencies or vulnerability to problem gambling. We propose that players who struggle with depressive symptoms may find dark flow appealing because it offers a temporary reprieve from troubling thoughts. However, extended stays in this “dark” zone can exacerbate existing issues.
mindfulness, depression, dark flow, mind-wandering, gambling
For most players, slot machines are primarily a form of entertainment, thanks to their immediate feedback, dynamic audio-visual elements, and unpredictable reward schedules (Griffiths & Parke, 2005; Haw, 2008; Haas & Edworthy, 1996). However, a small but notable portion of gamblers develop serious problems, including escalating debt, strained relationships, and even criminal behavior to finance their play (Blaszczynski, Sharpe, Walker, Shannon, & Coughlan, 2005; Lahn, 2005).
Arousal as a Reinforcer
Physiological arousal is often considered a key driver of gambling behavior, peaking after wins and dipping after losses (Coventry & Constable, 1999; Dixon et al., 2010; Lole, Gonsalvez, Blaszczynski, & Clarke, 2011). The relationship between arousal and problematic gambling remains less clear, with some studies suggesting that problem gamblers show higher arousal (Meyer et al., 2004) and others indicating a hypo-arousal, or tolerance-like effect (Paris, Franco, Sodano, Frye, & Wulfert, 2010).
Escapism and Dark Flow
Beyond arousal, certain players are drawn to slots for emotional relief. This relief often manifests as a highly immersive state—sometimes called the “slot-machine zone” or dark flow (Dixon, Stange, et al., 2017). While dark flow mimics flow states from positive psychology in terms of heightened focus and distorted time perception (Csikszentmihalyi, 1992), it carries negative consequences when gamblers prolong their play and accumulate financial losses. Research links dark flow to higher problem gambling risk and depression (Murch, Chu, & Clark, 2017; Dixon, Graydon, et al., 2014).
Implications for Gambling Regulation and Harm Reduction
Distinguishing reward-based enjoyment from immersion-based enjoyment is vital for developing strategies that minimize gambling-related harm. Slot-machine design elements—such as multiline play, rapid spin rates, and engaging feedback—can intensify both reward reactivity and dark flow. Regulators, researchers, and casino operators must consider how these features can be managed or modified to protect vulnerable individuals.
Conclusion
Our study underscores the importance of recognizing dark flow as a separate, potentially problematic pathway to enjoyment, particularly among individuals with depressive symptoms or at risk for problem gambling. By highlighting the dual nature of slot-machine enjoyment—both a “light” path via reward excitement and a “dark” path via immersive escapism—these findings contribute to a deeper understanding of how slot machines can entertain while also posing serious risks for certain players.
