Difficulty with making decisions is one of the features of depressive illness. However, the particulars of decision-making in individuals suffering from depression are poorly understood. In this thesis, the relationship between depression and decision-making was explored in three studies, conducted both on the Internet, with participants recruited from the Internet community, and in person, using college undergraduates. The studies focused on two aspects of decision-making: (1) general approach to decisions, including initial reactions to decision, styles of decision-making, and self-perception as a decision-maker, and (2) decisional effectiveness, or the ability to make use of good decision-making strategies to arrive at a choice that is in the decider's best interest.

When participants were prompted to examine decisions carefully, the productivity of decisions was unrelated to the level of depressive symptoms; depressed individuals were also not more likely to have any particular decision-related goals. However, when prompts for careful consideration of decisions were not present, depressed individuals made inferior choices. They were found to use fewer productive decision-making strategies, and were less likely to learn from their past experiences in similar situations. Level of depressive symptoms was also related to approaches to decisions and styles of decision-making. Depressed individuals became more anxious when faced with a decision, and preferred to remain passive, procrastinating or avoiding decisions. Finally, they were more likely to think poorly of their abilities as decision-makers and to not trust their intuitions. The results suggest that the failure to use adaptive decision-making strategies spontaneously is an important factor in determining the poor quality of the choices made by depressed individuals, and that prompting the use of such strategies improves decision-making considerably.