Stimulus Dynamics and Temporal Discrimination: Implications for Pacemakers

The purpose of the present study was to observe the functional relationship between stimulus dynamics and stimulus duration judgments in humans. Stimulus duration was defined as the length of time that a spinning sphere appeared on a computer screen. Stimulus dynamics were defined by how quickly the sphere rotated on its y-axis. Using a logarithmic scale, a psychophysical bisection task was used to divide stimulus durations into two categories, short and long. Across three experiments, participants' duration judgments were longer the faster the sphere was rotated. This effect was observed over both a long and short temporal scale and over a wide range of stimulus dynamics despite the fact that the reinforcement contingencies penalized participants for this effect. The results are discussed in terms of perceived change as the possible basis of temporal duration estimation. This hypothesis was investigated through applications of the leading quantitative models of temporal discrimination to the present data.