Dynamic criteria in duration discrimination tasks: An alternative to the scalar property of time perception?

Our ability to discriminate short durations can be studied through Signal-Detection-Theory based models. They incorporate the sensory, decision, and response mechanisms that govern observers’ responses in duration discrimination tasks, and serve as a guide to test substantive hypotheses about each of these components. The standard version of these models states that the sensory mechanism relies solely on the magnitude of the difference in duration of the stimuli to be compared. This is incompatible with some empirical results, which have shown that psychometric functions change with the duration of the reference stimulus. These results have been attributed to some form of the scalar property of time perception, but they could also be produced by shifts in decisional criteria. Here we present a series of four models that incorporate the scalar property, decisional criteria that vary with stimulus duration, or both, along with the standard model. We show that each model gives rise to psychometric functions with distinct characteristics, which raises the question of whether these models are also distinguishable in practice. We tackle this question through a simulation study whose results show that parameters can be adequately recovered, and that the data-generating model can be correctly selected using goodness-of-fit procedures. This framework provides a solid ground to design experiments that allow testing how sensory and decisional mechanisms contribute to judgements in duration discrimination tasks.