Abstract:

This article thoroughly reviews the past literature and studies on time perception of a small range of durations. The scalar timing theory of Gibbon (1991) and collaborators, which emphasizes the importance of a central timekeeping mechanism, describes the origin and the function of scalar timing in human performance. Many experimental results support the idea that humans can have a favorite duration, that is, an interval length that gives a lower Weber fraction and maximum sensitivity. A transitional point, perhaps around 2s or less than 2s, decides subjects’ timing bias and reflects a fundamental time limitation of humans in processing information. The present study aims at investigating the scalar property and the source of variance in short duration (6s-24s) estimation.
Based on the previous studies, we used the single-task program and incorporated the prospective paradigm in this study. From the perspective of psychophysics and by using a duration reproduction method, three experiments were conducted to investigate the scalar property, the source of variance, the transitional point, and the nature of the Weber function in temporal process of humans. The intervals ranging from 6s to24s were selected and used as physical durations in the experiments, and a geometric stimulus was presented in visual mode on the computer screen. Fifty-five participants volunteered in the experiments, and all the participants were tested individually in sessions that lasted 50-60 minutes. The analysis of variance was then conducted on the data collected from these experiments.
The experimental results showed that the motion status (kinetic or static) and the rotating angles significantly affected the participants’ temporal judgments. Compared with the static conditions, the effects of kinetic stimulus were more significant. With the increase of rotating angles, the accuracy of duration estimation was increased. Physical durations of stimulus also showed a significant duration-lengthened effect. The speed of stimulus was another important cue used by the participants in estimating durations. The experimental results indicated that lower Weber fractions and the maximum time sensitivity for intervals were in 9s to 12s, and a transitional point occurred at 11.1s where the Weber fraction began to increase with longer durations. In contrary to overestimation of the shorter durations, the participants underestimated the longer durations.
Three major conclusions are derived from this study. First, the motion status, speeds, changes (rotating angles) of stimulus, and physical durations are the main source of variance of temporal judgment. Second, people consistently overestimate the shorter durations and underestimate the longer durations. The transitional point in duration estimation is 11.1s in the range 6s to 24s. Presenting sequences of intervals to humans not only affects the Weber function but also distorts perceived durations. Third, a piecewise continuous function is the best explanation for the Weber function. Inflectional points of the Weber function (12s and 21s) derived from this study are, to some extent, consistent with the transitional point of 11.1s in duration estimation

Key words: time estimation, the scalar property, source of variance, the Weber function, the transitional point