The work presented here uses a simple stochastic model as a cognitive psychometric tool for analyzing response time data in the Go/No-Go Discrimination task with motivationally distinct conditions. The parameters of the model inform us of underlying cognitive mechanisms because they have an established psychological meaning and allow us to quantify a subjects ability and response caution. Using these model parameters, we focus on the differences between subjects with varying degrees of substance abuse and antisocial behavioral disorders and show that there are reliable differences between the decision mechanisms of these subjects. Using data from executive working memory tasks, we postulate that these differences in cognitive processes might be due to differences in working memory capacity. Ultimately, we show that formal cognitive modeling has the potential to provide valuable insights into clinical phenomena that cannot be captured by traditional data analysis techniques.