Subjective duration: A functional measurement analysis

Subjects judged the total duration of two intervals of time that varied from 0 to 30 sec. The data obeyed the parallelism prediction of a simple weighted adding model. According to functional measurement methodology, this observed parallelism provides joint support for the adding model and for the assumption that the graphic rating response provides a valid interval scale. Furthermore, parallelism allowed construction of the psychophysical time function. The obtained function was essentially linear in the range 0-30 sec. This result is compared with results of previous studies, with particular regard to the method of fractionation. The usefulness of establishing a validated interval response measure for further studies of time perception was pointed out.