This paper explores risky choice patterns in an experimental setting and develops and tests a model of decision using time as a measure of effort. Patterns of decision time are tested statistically, shown to depend on characteristics of the risky alternatives reflecting the costs and benefits of choice, and are shown to correspond with the predictions of an optimization model. There are two relevant fields of literature for this paper. The first addresses the effects of the similarity of risky alternatives on choice (Rubinstein 1988; Aipurua et al. 1993; Leland 1990, 1992a, 1992b, and 1992c; Buschena 1992). Similarity models offer an explanation for violations of the Expected Utility model (EU). These models' predictions are motivated through tradeoffs between the costs and benefits of evaluation effort akin to arguments of Bounded Rationality (Simon 1960; March 1978). The second area of relevant literature uses evaluation time to measure decision effort, finding significant relationships between evaluation effort and the importance of choice. Specifically, these models hold that evaluation time depends significantly on measures of the differences in utility between the alternatives. Work of particular interest for this paper are empirical efforts by Dashiell (1937); Petrusic and Jamieson (1978); Payne, Bettman, and Johnson (1993); and Wilcox (1993a, b).