Waiting in inter-temporal choice tasks affects discounting and subjective time perception

The literature on human delay discounting behavior is dominated by experimental paradigms, which do not impose actual delays. Given that waiting may be aversive even on short timescales, we present a novel delay discounting paradigm to study differences in delay discounting behavior either when real waiting is involved, or not. This paradigm retains the fundamental trade-off between rewards received versus their immediacy. We used hierarchical Bayesian modeling to decompose and test models that separate discounting and subjective time perception mechanisms. We report 2 experiments that also explore the magnitude effect and gain-loss asymmetry. In both experiments, we found greater discounting and nonlinear (convex) time perception in the online waiting task, which required waiting after each choice, compared to a control condition where waiting was deferred until the end of the experiment. Discounting was also measured by a parameter of a hyperbolic-type model and related to reversals of preference between initial desire to wait and then not doing so. These results from our novel paradigm support the emerging view that subjective time perception plays an important role in intertemporal choice in addition to discounting tendencies.