Measurements of the apparent duration, numerosity, familiarity, predictability, and organization of musical sequences were obtained to resolve conflicting claims about the effects of stimulus variables on duration judgments and to assess whether subjective number is an effective mediating variable underlying duration judgments. Intervals filled with perceptually familiar, organized, and predictable sequences of musical notes were judged by verbal estimation and, in most cases, by magnitude estimation to be longer and to have more notes than their perceptually unfamiliar reverse counterparts. The relationship between perceived and physical duration or number is consistent with Stevens's law, with exponents typical of reported values. Temporal and numerosity exponents derived from verbal estimates, but not from magnitude estimates, were higher for familiar, organized, and predictable sequences, but only when sequences were not paired with their reverse counterparts. Exponents and intercepts were not independent, but were inversely related; both may be needed to describe the duration and numerosity data.Duration perception is affected by several factors. Time intervals containing complex, unfamiliar, more numerous, or less predictable stimuli are estimated to be longer than intervals containing simpler (e.g

Time estimates of 1 1/2-, 5¼-, and 14 1/2-min intervals were obtained from 12 American graduate students and 12 Indian graduate students by the methods of verbal estimation and cross-modality matching. Material presented during stimulus intervals varied in degree of meaningfulness. Each subject was tested on 4 successive days with basically the same material in order to determine the effects of repetition. The relationship between perceived and physical time was found to follow Stevens' power law, and confidence limits of exponents obtained in this study include the exponents previously reported for short durations. Neither actual judgments nor exponents were affected by cultural background or by cognitive factors such as memory for material presented in the interval, familiarity, complexity, degree of meaningfulness, and repetition. It had previously been reported that time judgments were dependent on these cognitive factors. In light of the present research, it is necessary to review and replicate those studies which support a cognitive view of time perception.

Time estimates of 12 intervals of 15 to 65 sec. duration were obtained from 30 subjects by one of two methods, magnitude estimation and cross-modal matching. Three kinds of sequences of musical notes were presented during stimulus intervals; repetitive, melodic, and random. Within all sequences, notes were of equal duration and with equal pauses between them. In all cases, the relationship between perceived and physical time is consistent with Stevens' power law. Exponents derived from both kinds of estimates were significantly affected by the content of the interval. Exponents derived for repetitive sequences were not different from 1 and were significantly larger than exponents derived from random or melodic sequences. These results are inconsistent with the view that the predictability, familiarity, or codability of event occurring in the stimulus interval is inversely related to the perceived duration of that interval. There is some indication that the effect of the content of the interval on judgments of duration varies with the magnitude of the duration being judged. Perhaps the relationship holds only within certain parameters and, when these are exceeded, other factors mask the effect. A two-process theory of time perception, one which considers these other factors and explains the present results, is proposed.

No abstract

The intramodal range effect (an inverse relationship between stimulus range and exponent in Stevens's power law) has been well documented, but its conditions have not been tested. Both the estimates of stimulus magnitudes and their exponents are affected by context, stimulus location, and different standards and moduli, but how these variables might interact with the variable of stimulus range has not been studied. In the present research, exponents were derived from magnitude estimates of line length for each of three different stimulus ranges at two different locations on the scale of length, with or without a modulus. Moduli of 50 and 500 permitted an analysis of the effect of response magnitude on the range effect. Because different ranges had stimulus values in common, the effect of range and location on exponents from those common values could be determined. Exponents decreased as stimulus range increased, but only in the free-modulus condition. For that condition, exponents derived from magnitude estimates of only the common stimuli also showed the range effect and response magnitude did not influence the range effect. Exponents were higher for stimulus ranges at the lower location, but location does not appear to contribute to the range effect. Although the range effect is not explained, the conditions under which it holds and some factors that may influence it are considered.