Duration judgment and the experience of change

Predictions based on storage size, processing effort, and change models of time estimation were tested in five experiments. The first of these presented subjects with stimulus patterns that varied on dimensions of sensory-event number and uncertainty. Subjects estimated the duration of time periods using the reproduction method. Duration estimates were most accurately predicted by the number of sensory events in each pattern. This relationship was generally positive, although the specific function relating these variables was dependent upon clock duration. The change model seemed to fit these data best. Experiment 2 demonstrated that the relationship between sensory change and judged duration was not due to the total time of sensory input. Experiments 3, 4, and 5 tested the effects of several different types of change. In Experiments 3 and 4, the number of sensory events was held constant, but the regularity of their spatial presentation was varied. In both experiments, duration judgments were positively related to the number of changes that occurred. Because the manipulations used in these experiments produced differences in the visual complexity of stimulus patterns, the argument could be made that storage size or processing effort accounted for the size of duration judgments. Experiment 5 tested the effects of change while holding the visual complexity of stimulus patterns constant. A positive relationship between duration judgments and number of changes was again found.