Despite the prevalence of problem gamblers and the ethical issues involved in studying gambling behavior with humans, few animal models of gambling have been developed. When designing an animal model it is necessary to determine if behavior in the paradigm is similar to human gambling. In human studies, response latencies following winning trials and near win trials are greater than those following clear losses. Weatherly and Derenne (Anal Gambl Behav 1:79–89, 2007) investigated whether this pattern was found with rats working in an animal analogue of slot machine gambling. They found a similar pattern of response latencies but the subjects' behavior did not come under control of the visual stimuli signalling the different outcomes. The animal model of slot machine gambling we used addressed procedural issues in Weatherly and Derenne's model and examined whether reinforcer magnitude and the presence of near win trials influenced response latency and resistance to extinction. Response latencies of the six female Norway Hooded rats varied as a function of reinforcer magnitude and the presence of near-win trials. These results are consistent with prior research and with the idea that near win trials serve as conditional reinforcers.