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We report a series of experiments designed to demonstrate that the presentation of a sound can facilitate the identification of a concomitantly presented visual target letter in the backward masking paradigm. Two visual letters, serving as the target and its mask, were presented successively at various interstimulus intervals (ISIs). The results demonstrate that the crossmodal facilitation of participants' visual identification performance elicited by the presentation of a simultaneous sound occurs over a very narrow range of ISIs. This critical time-window lies just beyond the interval needed for participants to differentiate the target and mask as constituting two distinct perceptual events (Experiment 1) and can be dissociated from any facilitation elicited by making the visual target physically brighter (Experiment 2). When the sound is presented at the same time as the mask, a facilitatory, rather than an inhibitory effect on visual target identification performance is still observed (Experiment 3). We further demonstrate that the crossmodal facilitation of the visual target by the sound depends on the establishment of a reliable temporally coincident relationship between the two stimuli (Experiment 4); however, by contrast, spatial coincidence is not necessary (Experiment 5). We suggest that when visual and auditory stimuli are always presented synchronously, a better-consolidated object representation is likely to be constructed (than that resulting from unimodal visual stimulation). (Contains 7 footnotes and 9 figures.)

Despite the rapid growth of research on the crossmodal correspondence between visually presented shapes and basic tastes (e.g., sweet, sour, bitter, and salty), most studies that have been published to date have focused on shape contour (roundness/angularity). Meanwhile, other important features, such as symmetry, as well as the underlying mechanisms of the shape-taste correspondence, have rarely been studied. Over two experiments, we systematically manipulated the symmetry and contours of shapes and measured the influences of these variables on shape-taste correspondences. Furthermore, we investigated a potential underlying mechanism, based on the common affective appraisal of stimuli in different sensory modalities. We replicated the results of previous studies showing that round shapes are associated with sweet taste, whereas angular shapes are associated with sour and bitter tastes. In addition, we demonstrated a novel effect that the symmetry group of a shape influences how it is associated with taste. A significant relationship was observed between the taste and appraisal scores of the shapes, suggesting that the affective factors of pleasantness and threat underlie the shape-taste correspondence. These results were consistent across cultures, when we compared participants from Taiwanese and Western (UK, US, Canada) cultures. Our findings highlight that perceived pleasantness and threat are culturally common factors involved in at least some crossmodal correspondences.