Rationale: Impulse control deficits are thought to underlie criminal offending. Impulsive choice is a facet of impulse control that refers to a preference for immediate over delayed rewards. This facet of impulse control has been measured empirically using the Iowa Gambling Task (IGT), which provides a metric of overall disadvantageous decision-making, as well as metrics of specific maladaptive decision-making strategies. Purpose: To investigate impulsive choice as a measure of impairment in offenders as reflected by performance on the IGT, and to examine maladaptive decision-making strategies that may mimic real-life decisions to engage in illegal behaviour. Methods: 100 Canadian federal offenders (34% female, mean age = 39.14 ± 9.74) and 89 controls (39% female, mean age = 37.04 ± 10.79) completed the IGT. The IGT involves repeatedly choosing cards from four decks. Two decks are “good” and result in a net gain on the task, and two decks are “bad” and result in a net loss. Decks offer a fixed reward, but vary in loss magnitude and frequency. IGT data were analyzed for net score (number of good choices minus number of bad choices), learning across the task, and deck switching patterns. Other assessments included data on offenders’ current sentence and risk for reoffence level. Results: Offenders performed significantly poorer than controls in terms of net score. Controls learned the advantageous strategy across the task but offenders did not. Offenders also made greater use of a “win-stay/lose-shift” strategy. Low-risk offenders performed significantly better than medium- or high-risk offenders on the IGT. Conclusion: These results suggest that, compared with controls, offenders tend to make riskier choices and use maladaptive decision-making strategies that provide a larger immediate reward but are disadvantageous in the long term. The IGT, as part of a comprehensive assessment of risk, may provide valuable information for preventing criminal offending and recidivism.

Criminal offending is thought to be related to impulse control problems. Research has linked offending to poor performance on a decision-making task known as the Iowa Gambling Task (IGT). On the IGT, participants repeatedly choose cards from four decks that provide wins and losses of points. Two decks are “good” and result in an overall gain on the task, and two decks are “bad” and result in an overall loss. In this study, 100 Canadian federal offenders and 89 non-incarcerated control participants completed the IGT. Offenders performed worse than the control group overall, and control participants but not offenders learned the best strategy (i.e., choosing from good decks) over the course of the task. Additionally, offenders with a “Low” criminal risk rating did better than those at “Medium” or “High” risk levels. These results suggest that the IGT may provide important information about the cause and prevention of criminal offending.

Master of Science (MSc)

Thesis