Scalar timing (expectancy) theory : A comparison between prospective and retrospective duration

One hundred and twenty human subjects participated in both a prospective and a retrospective duration reproduction experiment. A scaling approach to the collected data can be found in A. D. Eisler et al. (2004). In the present part of the comprehensive project the data were treated according to the requirements of Scalar Timing (Expectancy) Theory (SET). For both the prospective and the retrospective data sets the distribution of the ratio reproduction/standard durations proved skewed to the right, and the coefficient of variation decreased with the durations rather than being constant. Both findings are at variance with SET, which assumes the validity of Weber's law and agreement between subjective and chronometric time. However, the outcome could be predicted from the generalized Weber law (common for many continua, see H. Eisler, 1965) and a nonlinear psychophysical function for duration. The symmetric distributions obtained from animals are explained by stimulus error. From the point of view of SET, as opposed to the scaling approach, except for greater scatter, the retrospective durations did not differ from the prospective in any essential way.