RELATIVE SENSITIVITY TO FILLED VS. EMPTY INTERVALS DEPENDS ON METHODS: EVIDENCE FROM DEVELOPMENTAL DATA
Two experiments involving child participants were conducted to test the relative effect of nontemporal factors and age on duration discrimination. In Experiment 1, a method similar to the time test of the Seashore Measures of Musical Talents, which involves a forced-choice presentation of intervals and a 800-ms standard, was employed. Results showed that the discrimination is better with filled intervals (a continuous signal) than with empty intervals (a silent period between two brief signals). As well, discrimination gradually improved with age, from 9 years old to adulthood, and this was generally true with intervals presented both in the visual and in the auditory modes, with either filled or empty intervals. Experiment 2 showed that children, as reported in previous studies with adults, have better discrimination with empty than with filled intervals in conditions where a 250-ms standard, visual signals, and an adaptive procedure are employed. There was an apparent contradiction of the two experiments regarding the structure --filled vs. empty-- of the interval. The filled vs. empty difference may depend on the method (Seashore-like vs. adaptive), on the range of duration, or on the combination of both factors.