Psychological conditions of the comparison of time-intervals. (1) For intervals up to half a second the limiting stimuli are dominant in consciousness; for longer intervals, the time between them. (2) The temporal content is in the first case the succession of sensations, in the second the duration of the processes which run their course between the sensation-pairs. (3) The apprehension of least intervals is usually rhythmical. (4) And rhythm is, in part at least, an aesthetic factor. (5) The difference between perception-time and memory-time only exists for the longer intervals. (6) There occur constant differences in the attentional adaptation, for different lengths of intervals. § 1. Dependence of temporal estimation on the intensity and the change of intensity of the limiting sensations. Apparatus. Experiments. Results. (1) The influence of intensity is not due (to any great extent) to alteration of the limiting sensational-duration, nor to association, nor to general phenomena of the attention. Rather must the question of rhythmic time-apprehension be examined for itself. (2) There exists, under certain conditions, an elementary relationship of the rhythmical impression: the same rhythmical expression may arise from the most diverse causes, when likeness and difference of the impressions remain analogous. This helps to explain the dependence of temporal estimation or change of intensity and quality. Perhaps subjective accentuation is the attentional fact, which mediates between the two.
The object of this investigation, carried on in the laboratory of Clark University, was first, to determine "what the mind does with a series of simple auditory impressions in which there is absolutely no change of intensity, pitch, quality, or time-interval"; and second, to find what effect upon the rhythmical grouping is brought about by regular variations with respect to time-interval or intensity of the sounds in the series. The sounds used were telephone clicks produced in an induction circuit by breaks in a constant primary circuit. These clicks form a more uniform series than was obtained in the experiments of Dietze or of Angell and Pierce. The chief results of the work may be stated in the author's words: "In a series of auditory impressions any regularly recurrent impression which is
