Violation of the scalar property for time perception between 1 and 2 seconds: evidence from interval discrimination, reproduction, and categorization

According to the hypothesis of a scalar property for time, the variability to time ratio should be constant. Three experiments tested the validity of this hypothesis in a restricted range of durations (standard values = 1, 1.3, 1.6, and 1.9 s). In each experiment, time intervals to be discriminated, reproduced, or categorized were presented with 2, 4, or 6 brief successive auditory signals marking 1, 3, or 5 intervals, respectively. In Experiment 1, participants were asked to indicate whether the interval(s) within a second series of sounds were shorter or longer than those of the first. In Experiment 2, the standard interval had to be reproduced. In Experiment 3, after 10 presentations of the standard, participants had to categorize each comparison interval as shorter or longer than the standard. In addition to showing that performance was generally poorer when only 1 interval was presented and remained about the same regardless of whether 3 or 5 intervals were presented (Experiments 1 and 3), the results demonstrated that the variability to time ratio is not constant across the standard interval conditions. Overall, the ratio is higher at 1.9 than at 1 s. This violation of scalar timing occurs whatever the method used and does not interact with the number-of-interval variable.