Bisensory response to temporal frequency in 4-month-old infants.

To investigate detection of auditory-visu al equivalence of rate, in the first two studies 4-month-old infants were shown pairs of check patterns flashing at 2, 4, and 8 Hz either in silence or while listening to a tone corresponding in rate to one member of the pair. In Study 1, rate of stimulation varied, whereas duty cycle (i.e., intensity) was kept constant. No evidence of bisensory matching of rate was found. In Study 2, rate and duty cycle covaried. Although no matching was found, the presence of the two most intense sounds led to a shift in looking toward lower rates of visual stimulation. In Study 3, rate was kept constant (2 Hz), whereas duty cycle was varied. No matching was found but, as in Study 2, the presence of the most intense sound led to a shift in looking toward the less intense visual stimuli. Although these findings are contrary to previous reports of auditory-visual matching of rate, they do indicate that sound influences visual preferences via an intensity-bas ed response mechanism. A great deal of the stimulation available to an observer is multisensory in nature. Quite often, the stimulation that impinges on the different sensory modalities may be related by virtue of some common property such as rate, rhythm, duration, shape, location, intensity, or some combination of these. The ability to detect these common properties allows us to derive higher level invariants that are no longer specific to any single modality. In general, our ability to detect intersensory relationships reflects the general integrative activity of the central nervous system and forms the foundation upon which many of our higher level perceptual, cognitive, and linguistic functions are based. In fact, some have considered the degree to which an organism is able to integrate inputs from different modalities as a criterion for evaluating the organism's psychological standing when