Naiveté, projection bias, and habit formation in gym attendance

We implement a gym-attendance incentive intervention and elicit subjects' predictions of their postintervention attendance. We find that subjects greatly overpredict future attendance, which we interpret as evidence of partial naiveté with respect to present bias. We find a significant postintervention attendance increase, which we interpret as habit formation, and which subjects appear not to predict ex ante. These results are consistent with a model of projection bias with respect to habit formation. Neither the intervention incentives, nor the small posttreatment incentives involved in our elicitation mechanism, appear to crowd out existing intrinsic motivation. The combination of naiveté and projection bias in gym attendance can help to explain limited take-up of commitment devices by dynamically inconsistent agents, and points to new forms of contracts. Alternative explanations of our results are discussed

Naivete, projection bias, and habit formation in gym attendance

We develop a model capturing habit formation, projection bias, and present bias in an intertemporal-choice setting, and conduct a field experiment to identify its main parameters. We elicit subjects' pre- and post-treatment predictions of post-treatment gym attendance, using a habit-formation intervention based on Charness and Gneezy (2009) as an exogenous shock to treated subjects' gym preferences. Projection-biased subjects, projecting their current habit state onto their future expectations, will, ex-ante, under-estimate any habit-formation effect of our treatment. Naive present-biased subjects in both groups will overestimate their future attendance. Like Charness and Gneezy, we find subjects do form a significant short-run habit, though we find substantial decay caused by the semester break. Subjects appear not to embed this habit formation into their ex-ante predictions. Approximately one-third of subjects formed a habit equivalent to the effect of a $2.60 per-visit subsidy, while their predictions correspond to 90% projection bias over this habit formation. Moreover, subjects greatly over-predict future attendance, which we interpret as evidence of partial naivete with respect to present bias: they appear to expect their future selves to be two-thirds less "present biased" than they currently are

Habit formation and naïveté in gym attendance: evidence from a field experiment

Abstract We extend the gym-attendance study o