On the replication of Kristofferson's (1980) quantal timing for duration discrimination: some learning but no quanta and not much of a Weber constant.

This study revisited Kristofferson's (Perception & Psychophysics 27:300-306, 1980) report showing that, with sufficient practice at interval discrimination, the relationship between timing variability and physical time is a step function-in other words, that psychological time is quantized. Two participants completed 260 sessions of a temporal discrimination task, 20 consecutive sessions for each of 13 base durations ranging from 100 to 1,480 ms. The data do not replicate Kristofferson's (Perception & Psychophysics 27:300-306, 1980) quantal finding, and it is argued that the effect Kristofferson reported may have been due to specific methodological decisions. Importantly, the data show (1) some limitation of Weber's law for time, even for the narrow range of the present investigation, and (2) that extensive training provides some modest benefit to temporal discrimination, mainly for longer intervals, and that this benefit primarily occurs in the first few sessions.