The determinants of decision time in an ambiguous context

This paper builds on the data from a published paper on behaviour under ambiguity (Conte & Hey, 2013)—henceforth C&H—to explore the determinants of decision time. C&H categorized individual subjects as being of one of four types (of decision-maker)—Expected Utility, Smooth Ambiguity, Rank Dependent and Alpha Expected Utility—by using the decisions of the subjects, but did not look at the decision times of the different types. We take as given the categorization identified by C&H, and explore whether the classification can explain the decision times of the subjects. We investigate whether and why different types take a different amount of time to decide. We explore the effects of various features related to (mainly psychological) theories of the process of decision-making—i.e., experience with the task, complexity, closeness to indifference and similarity of the options. Our results show that different types take a similar time to make their decisions on average, but decision times of different types are explained by different features of the decision task. This paper is the first investigating the heterogeneity of decision times based on a classification of subjects into different types in an ambiguous (rather than risky) decision context.