Completeness, the most commonly assumed axiom in preference theory, has not received much attention from the experimental literature. Indeed, incomplete preferences model a cognitive phenomenon (an agent's inability to compare alternatives), and therefore cannot be directly revealed through...

We propose an experimental design allowing a behavioral test of the axiom of completeness of individual preferences. The central feature of our design consists in enabling subjects to postpone commitment at a small cost. Our main result is that preferences are significantly incomplete. We use...