Slot machines were once an afterthought on casino floors, where table games were the real action, but as Andrew Thompson details in a piece on the Verge, slots have come to represent the majority of many casino’s business, now earning casinos 70% to 80% of their revenue compared to less than 50% in the 1970s. And now, designers are taking notice, adopting similar design tactics to make games and apps of all sorts stick with users and you can incorporate it into any of your design work.
The addictiveness of slot machines is what makes them so popular with both gamblers and casino owners. Their digital interfaces, often with big curved screens, brand tie ins and obnoxiously cheery music, are designed to draw people in. But it’s the way they dish out rewards that really seals the deal, and slot machine makers learned these invisible design elements from basic psychology. B.F. Skinner‘s famous study on reward is a major touchpoint here:
To keep players gambling, all slots rely on the same basic psychological principles discovered by B.F. Skinner in the 1960s. Skinner is famous for an experiment in which he put pigeons in a box that gave them a pellet of food when they pressed a lever. But when Skinner altered the box so that pellets came out on random presses — a system dubbed variable ratio enforcement — the pigeons pressed the lever more often. Thus was born the Skinner box, which Skinner himself likened to a slot machine.
The Skinner box works by blending tension and release — the absence of a pellet after the lever is pressed creates expectation that finds release via reward. Too little reward and the animal becomes frustrated and stops trying; too much and it won’t push the lever as often.
Finding this sweet spot is the goal for all slot makers. Since the advent of magnetic cards which players can use to get extra rewards like free hotel rooms from casinos for loyalty, figuring out the magic formula has become easier. These cards keep track of players behavior and allow casino owners to give them the exact rewards that the data shows will keep them playing.
Another psychological concept that’s become a pillar of the slots industry is psychologist Mihaly Csikszentmihalyi‘s idea of “flow,” the state in which a perfect storm of activity and desire coalesces to produce a mental state where hours can seem to go by in minutes. Natasha Schüll, a professor at MIT, applied this concept to the world of slot machines.
During “flow,” time speeds up (hours feel like minutes) or slows down (reactions can be made instantly) and the mind reaches a state of almost euphoric equilibrium. Schüll, in her book, describes Csikszentmihaly’s four criteria of flow: “[F]irst, each moment of the activity must have a little goal; second, the rules for attaining that goal must be clear; third, the activity must give immediate feedback; fourth, the tasks of the activity must be matched with challenge.” For most of their history, slots easily fulfilled the first two criteria; after lowering volatility, they fulfilled the third criterion, and with the introduction of multiple lines, endless bonus rounds, and the occasional mini-game, they finally fulfilled the four criteria.
It’s easy to see why the combination of a highly addictive interface and detailed consumer data would appeal to Silicon Valley. As Thompson points out, several large casinos and gambling brands have recently acquired gambling games for smartphones and Schüll says she is often approached by tech people who want to use her book to crack the slot machine code. Tinder, in particular, is cited as an example of this slot machine-esque approach. Using the psychology of reward to get customers to return is nothing new, but with more quantifiable data available to back up these hypotheses and studies, our experiences with tech could become more like an addiction than ever before.