The neural bases of cross-modal correspondences: reality or wishful thinking?
Last modified: 2013-05-05
Abstract
There has recently been resurgent interest in the notion of cross-modal correspondences – i.e. stimulus features that may be preferentially integrated. The extent to which any such correspondences emanate from intrinsic anatomical connectivity or instead from learned (presumably statistical) regularities in the environment remains unresolved. Anatomical data from non-human primates would suggest that high-frequency auditory representations together with peripheral visual field representations in primary cortices are a preferred locus of low-level integration, whereas functional studies in humans have repeatedly demonstrated effects with centrally-presented stimuli and a range of auditory pitches/bandwidths. The present psychophysics and EEG study examined whether auditory-visual integration systematically varies with acoustic pitch and visual eccentricity. Subjects viewed 2 annuli (either foveally-presented or at 12.5° eccentricity, with surface area controlled for cortical magnification) and indicated which, if either, changed its brightness. The paradigm followed a 3x3 within subject design: (no, foveal, or peripheral brightness change) x (no, 500Hz, or 4000Hz pure tone presentation; the latter of which were controlled for perceived loudness). Accuracy data were analyzed according to signal detection theory, using sensitivity (d’). Reaction time data were analyzed after dividing by detection rates, using the multisensory response enhancement metric (MRE; see Rach et al., 2011 Psychological Research). Preliminary data suggest there to be a main effect of pitch (i.e. larger d’ and MRE when the multisensory conditions included a high pitch vs. low pitch sound). There was no evidence of a main effect of eccentricity or interaction between factors. Ongoing EEG analyses will likewise be discussed.
Keywords
auditory-visual, crossmodal correspondence, EEG