The most popular models of decision under uncertainty such as expected utility (EU, von Neumann and Morgenstern 1947), and cumulative prospect theory (CPT; Tversky and Kahneman 1992) – assume that the decision maker evaluates each prospect separately and then chooses the prospect with the highest EU (or the highest CPT value). Regret theory (Bell 1982; Fishburn 1982; Loomes and Sugden 1982) is a bold exception in that the forgone alternative does influence the decision maker; hence this theory allows also for between-prospects interactions.