The Experiment 3 'bonus feature' machine resembled the free spins machine in Experiment 2 except spins were not free participants showed a clear preference for this machine also. In Experiment 2 the free-spins feature incorporated additional elements such as sounds, animations, and an increased win frequency participants preferred to gamble on this machine. In Experiment 1, participants did not prefer the machine with a simple free-spins feature. Participants then completed a testing phase where they could freely switch between the two machines. In each experiment, participants were exposed to two computer-simulated slot machines-one with a free-spins feature or similar bonus feature and one without. This series of three experiments investigated the free-spins feature using slot machine simulations to determine whether participants allocate more wagers to a machine with free spins, and, which components of free-spins features drive this preference. Despite increasing research into how the structural characteristics of slot machines influence gambling behaviour there have been no experimental investigations into the effect of free-spins bonus features-a structural characteristic that is commonly central to the design of slot machines.
