The Shape of Forgetting
Prof. Johannes Haushofer
Goh Keng Swee Professor of Economics
National University of Singapore
Prospective memory refers to the ability to remember to perform a specific action, such as taking a medication or paying a bill, at a specified future time. I present three studies on the shape of prospective memory as a function of time. In all studies, participants have to perform a simple action — sending a text message — at a specific time in the future — e.g. after 5 weeks — to obtain a monetary reward. In the first study, I find high rates of forgetting: For example, a reward worth 1.4 x the daily income is forgotten with 52 percent probability after 5 weeks. Forgetting is well-described by a power function. In the second study, when participants are discouraged from using their own reminders, forgetting is even stronger, but not by much. In the third study, participants overestimate their probability of remembering at long time horizons, but underestimate it at short time horizons.