ABSTRACT
If the number of publications on a given topic is a valid index of interest, then phenomena associated with motion in the auditory modality have enjoyed considerable attention over the last third of the century. However, of the nearly 80 papers published on this general topic in the last 30 years, less than 20 of these were based on experiments in which a sound source actually moved during the listening interval. In effect, most of the psychophysical and all of the physiological research published during this period utilized stimuli that only “simulated” some aspect of a sound source in motion relative to the listener. In this chapter, the various motion and motion simulation paradigms are discussed with particular attention given to the most commonly employed of these, the sequential presentation of discrete acoustic events (e.g., Altman and Viskov, 1977). Results from our laboratories, using the latter technique, are also presented. This work, conducted over the last 8 years, has led to a most curious observation, namely, that the temporal aspects of the stimulus sequence appear to be the sole determinant of whether or not motion is experienced with this paradigm. Conversely, we find that it is the spatial distribution of the discrete events, far more than the temporal, that seems to underlie the subject’s ability to correctly identify the direction of travel. Under some conditions one can even observe "motion without direction.” The implications of these and other observations are discussed.
