This article presents findings of cross-sensory dimensional interaction for the visual dimension of vertical position and the auditory dimension of pitch. Subjects were simultaneously presented with attributes from both dimensions and performed speeded classification of one dimension. There were four task conditions. The irrelevant dimension was varied orthogonally or held constant, and attributes were always Synesthetically congruent or always Synesthetically incongruent. Subjects displayed reaction time (RT) interference when the second dimension varied orthogonally (a failure of selective attention). In addition, redundancy gain was asymmetric. Reaction time facilitation was only present when attributes were Synesthetically congruent. Negatively correlated redundancy (incongruence) yielded neither facilitation nor interference. Interaction was unaffected by changes in the spatial origin of signals (Experiment 3) and was still evident when signals were temporally separated (Experiment 4). Several explanations for these results are considered. It is argued that these results may represent a new form of dimensional interaction.Numerous introspective reports examining the intrinsic correspondences between various qualities of sense have shown substantial agreement among subjects. High-pitched tones are consistently judged as corresponding with bright hues (Simpson, Quinn, & Ausubel, 1956; Wicker, 1968). Light gray is judged to correspond with loud tones, whereas dark gray corresponds with soft tones (Bond & Stevens, 1965;Stevens & Marks, 1965). Such correspondences are called synesthetic (literally, joining of the senses) meaning that they reflect a presumed connection among attributes from different sensory modalities. These cross-modal matches are often speculated to be the product of some abstract, higher order cognitive process greatly removed from perception (Marks, 1975(Marks, , 1978 see Ortmann, 1933).However, the correspondences of the so-called synesthetes certainly appear not to be allegorical and inferential. Synesthetes are individuals who, when presented with a physical stimulus in one sense modality (e.g., a tone), report the actual experience of sensory stimulation in a separate modality (e.g., a sensation [called a photism] of a patch of color). The photisms of most synesthetes are quite vivid and compelling for the subject (e.g., Luria, 1968). Moreover, scrutiny of early case-study accounts (e.g., Ortmann, 1933; Werner, 1940;Wheeler and Cutsforth, 1922) suggests that for the synesthetes, the intrusion of internal, phenomenal sense information upon external, attended sense information creates an experience very close to the perceptual experience.' Interestingly, the correspondences commonly observed in their photisms are the same correspon-We wish to thank Bill Prinzmetal, James Pomerantz, and an anonymous reviewer for their very helpful comments on an earlier version of this article. We acknowledge the capable assistance of Paul Little, David Chandross, and Angelique Cooper in running the experi...
