April 19, 2024

The next time you’re at a casino, take a good look around. Everything from the layout of the tables to the design of the carpets is specifically engineered to make gambling more seductive and get you spending more money. But perhaps nothing in a modern casino is more carefully designed than its slot machines. They now account for up to 85 percent of casino profits. And as cultural anthropologist and MIT researcher Kelly Schull shows in this episode of our podcast, they’re full of tricks designed to trick gamblers into playing longer and more frequently.

Schull’s research focuses on “near misses,” which occur when feedback for a loss approximates a win. For example, a near miss on a slot machine might be signalled by three cherries instead of two or four (and the odds of winning a specific symbol match the odds of the whole line). This feedback exploits learning processes that evolved to detect contingent rewards, such as the free throw in basketball, but they offer no practical use for improving performance in the case of a slot machine.

But despite inconsistencies in the experimental literature and concerns that near-miss effects might simply reflect an increase in the overall frequency of gambling, Schull finds that they do have a clear effect on gambling persistence. To test whether these effects might be attributed to the putative conditional reinforcement, she recently ran another experiment in which participants played a simulated slot machine for points and were presented with different frequencies of near-miss presentations. Across three experiments, she found that the highest frequency of near-misses was associated with the greatest amount of gambling persistence.