Do pupillary responses during authentic slot machine use reflect arousal or screen luminance fluctuations? A proof-of-concept study

Post-reinforcement pauses during slot machine gambling are moderated by immersion

The post-reinforcement pause (PRP) is an operant effect in which response latencies increase on trials following the receipt and consumption of reward. Human studies demonstrate analogous effects in electronic gambling machines that utilise random ratio reinforcement schedules. We sought to identify moderators of the human PRP effect, hypothesising that the magnitude of gamblers' PRPs is moderated by the type of reinforcing outcome (genuine wins vs. losses-disguised-as-wins [LDWs] vs. free-spin bonus features) and individuals' level of gambling immersion, a cognitive state linked to problem gambling. Experienced slot machine users (N = 53) played a real slot machine for 20 min. The dependent variable was defined as the time delay in the initiation of each bet ("Spin Initiation Latency"; SIL). Using 80% of trials, a linear model was fit regressing SIL on the independent variables (outcome type, immersion, and outcome-by-immersion interaction), and a larger group of covariates (participant ID, trial number, winnings, etc.) selected using double-robust LASSO-regularised regression. The previously unseen 20% of cases were used to validate the model. Positively reinforcing outcome types (wins, LDWs, bonus spins) showed significantly larger SILs than losses, indicating a PRP effect. Immersion did not predict response latencies, but win-by-immersion and LDW-by-immersion interactions indicated that pauses were greater among more immersed participants. The small number of free-spin bonus features showed similar trends that were not statistically significant. These results indicate that gamblers immersed in play remained sensitive to in-game reinforcement (contrary to a prevailing account), and provide guidance for researchers bridging laboratory research and real-world behaviour.

Engineered highs: Reward variability and frequency as potential prerequisites of behavioural addiction

Influential learning-based accounts of substance addictions posit the attribution of incentive salience to drug-associated cues, and its escalation by the direct dopaminergic effects of drugs. In translating this account to disordered gambling, we have noted how the intermittent nature of monetary rewards in gambling (i.e. the variable ratio) may allow for analogous learning processes, via effects on dopaminergic signalling. The aim of the present article is to consider how multiple sources of reward variability operate within modern gambling products, and how similar sources of variability, as well as some novel sources of variability, also apply to other digital products implicated in behavioural addictions, including gaming, shopping, social media and online pornography. Online access to these activities facilitates not only unparalleled accessibility but also introduces novel forms of reward variability, as seen in the effects of infinite scrolls and personalized recommendations. We use the term uncertainty to refer to the subjective experience of reward variability. We further highlight two psychological factors that appear to moderate the effects of uncertainty: 1) the timecourse of uncertainty, especially with regard to its resolution, 2) the frequency of exposure, allowing temporal compression. Collectively, the evidence illustrates how qualitative and quantitative variability of reward can confer addictive potential to non-drug reinforcers by exploiting the psychological and neural processes that rely on predictability to guide reward seeking behaviour.