This thesis is an investigation of the effect of slot machine characteristics on at risk gambling intentions (AGI), the illusion of control (IOC), and the amount individuals bet (ABL). A sample of problem and non-problem gamblers were used. Slot machine characteristics such as lighting, sounds and number of lines per play were investigated. It was predicted that problem gamblers would score higher on cognitive distortions than non-problem gamblers. A novel finding in the present study was a main effect of sound on the amount bet per-line (ABL) such that those playing with the sound low bet more per line. Another novel finding in this study was the positive correlation between IOC and AGI. These findings may help in the design of slot machines. The findings may also aid in the identification of at-risk groups for problem gambling by identifying those who have misconceptions about gambling.