In search of the preference reversal zone
A preference reversal is observed when a preference for a larger-later reward over a smaller-sooner reward reverses as both rewards come closer in time. Preference reversals are common in everyday life and in the laboratory, and are often claimed to support hyperbolic delay-discounting models which, in their simplest form, can model reversals with only one free parameter. However, it is not clear if the temporal location of preference reversals can be predicted a priori. Studies testing model predictions have not found support for them but they overlooked the well-documented effect of reinforcer magnitude on discounting rate. Therefore we directly tested hyperbolic and exponential model predictions in a pre-registered study by assessing individual discount rates for two reinforcer magnitudes. We then made individualised predictions about pairs of choices between which preference reversal should occur. With 107 participants we found 1) little evidence that hyperbolic and exponential models could predict the temporal location of preference reversals, 2) some evidence that hyperbolic models had better predictive performance than exponential models, and 3) in contrast to many previous studies, that exponential models generally produced superior fits to the observed data than hyperbolic models.