Abstract
In multi-sensory integration, vision generally has little influence on auditory duration judgments (Walker & Scott, 1981); provided sufficient quality of the auditory signal (Alais & Burr, 2004; Wada et al., 2003). However much of this research uses visual stimuli that are either static (Soto-Faraco, Spence, & Kingstone, 2004) or exhibit apparent motion (Getzmann, 2007). Here we explore the role of continuous motion in explaining surprising previous findings that visible striking gestures can in fact influence the perception of tone duration (Schutz & Kubovy, 2009); an influence at odds with ‘optimal integration’ as it cannot be explained by auditory ambiguity (Schutz, 2009). Our findings suggest the illusion stems in part from differences in perceiving stimuli exhibiting biological motion vs. non-motion (i.e. unmoving dots).
Our stimuli for the three experiments included two classes of dots: dynamic—based on long and short gestures used by a musician to strike a percussion instrument (used previously; Schutz, 2009) and static—based on single dots turning on for a ‘long’ or ‘short’ period of time. We asked participants to judge the durations of several sounds while ignoring concurrent visual stimuli. Overall, we found auditory duration ratings were strongly affected by visual duration when dots were dynamic, rather than static. However, we also found this effect was dependent upon our blocking structure. The illusion was strongest when participants experienced all of the dynamic visual stimuli before all of the static visual stimuli (Exp 1) or vice-versa (Exp 2); when intermingled the visual influence was minimal (Exp 3). We will discuss these results in light of currently theories of multi-sensory integration generally based heavily on experiments in which visual information is static, rather than dynamic as is experienced in our everyday perceiving.
Meeting abstract presented at VSS 2013