The development of decision making paradigms has prompted a consideration that an underlying deficit may assist in explaining substance dependence. However, despite these advances, little progress has been made in accounting for large inter-subject variance within previous studies. This failure continues to undermine many of the previous attempts to explain individual difference.

A study was undertaken to develop methods for analysing and describing individual response behaviours within a decision-making task. In addition, the effect of task manipulations such as feedback, penalties and practice were examined. Substitute medication maintained adults males were recruited for this study.

Findings from this research offer new insight into a possible link between task design and the response behaviours exhibited. This study emphasised the importance of individual response behaviours, and the necessity to consider individual data as a route to understanding concepts drawn from between groups analysis. Significant issues are raised that might impact on other existing paradigms and implications are proposed in relation to the assessment and treatment of substance dependence.