Time Consistency: Stationarity and Time Invariance

A sequence of experiments documents static and dynamic ``preference reversals'' between sooner-smaller and later-larger rewards, when the sooner reward could be immediate. The theoretically-motivated design permits separate identification of time-consistent, stationary and time-invariant choices. At least half of the subjects are time consistent, but only three-quarters of them exhibit stationary choices. About half of subjects with time inconsistent choices have stationary preferences. These results challenge the view that present-bias preferences are the main source of time inconsistent choices.