The Effects of Machine Balance and Free-Spins Features on Machine Preference and Bet Amounts.

Across two experiments, the current study investigated whether the balance displayed on slot-machine screens affects gamblers' decision making in a manner similar to the "house-money effect" observed in other gambling modes. The balance indicates the total amount the gambler has available to wager from. We manipulated initial slot-machine balance within a simulated slot-machine task. Participants gambled on each of two machines and then were able to switch between the two allowing us to assess the effect of machine balance on both preference and bet amounts. Experiment 1 also manipulated which machine incorporated a free-spins feature. In both experiments participants preferred to wager on, and made larger bets on, machines with higher balances. Experiment 1 replicated previous findings that people prefer to gamble on machines offering free spins. Together, these two experiments identify balance available as an additional slot-machine feature that contributes to slot-machine gambling behavior.

More Than Money: Experienced Positive Affect Reduces Risk-Taking Behavior on a Real-World Gambling Task.

Previous research indicates that when people participate in multi-trial games of chance, the results of previous trials impact subsequent wager size. For example, the "house money" and "break even" effects suggest that an individual's risk-taking propensity increases when financially winning or losing during a gambling session. Additionally, the "mood maintenance hypothesis" and affect regulation hypothesis suggest that people in positive and negative affective states are less and more likely to gamble than when in neutral affective states, respectively. In the present study, participants completed a series of trials on three computerized slot machines with varying expected values (EV; -10, 0, +10%) of return on investment, and they were paid a percentage of their final bankrolls in real money. Although results did not support the "house money" or "break even" effects, the "mood maintenance hypothesis" was robustly supported in all EV conditions. This is some of the first evidence supporting this theory using an ecologically valid, real-money gambling task.

Money in the Bank: Distortive Effects of Accumulated Earnings on Risky Choice.

A new study by Juechems et al. (2017) demonstrates that individuals take fewer risks as they accumulate monetary reward. The ventromedial prefrontal cortex plays a key role in the decision process, encoding both momentary reward and the context of the accumulated wealth.