Preverbal Infants’ Sensitivity to Synaesthetic Cross-Modality Correspondences

Abstract

Stimulation of one sensory modality can induce perceptual experiences in another modality that reflect synaesthetic correspondences among different dimensions of sensory experience. In visual-hearing synaesthesia, for example, higher pitched sounds induce visual images that are brighter, smaller, higher in space, and sharper than those induced by lower pitched sounds. Claims that neonatal perception is synaesthetic imply that such correspondences are an unlearned aspect of perception. To date, the youngest children in whom such correspondences have been confirmed with any certainty were 2- to 3-year-olds. We examined preferential looking to assess 3- to 4-month-old preverbal infants' sensitivity to the correspondences linking auditory pitch to visuospatial height and visual sharpness. The infants looked longer at a changing visual display when this was accompanied by a sound whose changing pitch was congruent, rather than incongruent, with these correspondences. This is the strongest indication to date that synaesthetic cross-modality correspondences are an unlearned aspect of perception.

Three-month-old human infants use vocal cues of body size

“…Previous research also shows that three-month-old infants are able to discriminate sounds based on pitch [28] and four-monthold infants map non-rigid transformations of object thickness and rigid transformations of height to differences in pitch [32]. Further, studies using preferential looking (giving infants an option to look at two different screens) demonstrate that infants prefer to look at matched visual/acoustic events between the height and pitch of a moving object consistent with the Doppler effect [32,33], at pairings between object size and vowel type (high frontal vowels with higher F 0 and formants versus low posterior vowels with lowered F 0 and formants [34]) and at matches between pitch and the expansion and contraction of objects [35].…”

“…That is, motion paired with emitted sounds may satisfy the input conditions of adaptations for picking up on invariant sound/object co-relations, irrespective of whether the object is a living thing vocalizing, or a non-living object producing noise [27][28][29][30][31][32][33][34]54]. However, because the acoustics produced by the living and non-living worlds are interestingly different from one another, both in terms of their properties and also in their affordances [9,16,22,23], the psychological mechanisms for representing and reasoning about the living versus the non-living worlds will likely become increasingly distinct from one another over the course of development.…”

“…2 Looking time paradigms are used with young infants because perceptual and oculomotor maturation occurs more quickly and uniformly than does gross and fine motor maturation, and thus looking times are more a reliable index of attentional patterns early in ontogeny [4,[28][29][30][31][32][33][34][35][36][37]. Three-month-olds were tested because previous findings suggest that infants of this age have adequate perceptual and oculomotor maturity for the current task [28][29][30][31][32][33][34][35][36][37][38][39]. 3 All sounds were played through a set of centrally located speakers behind the back curtain of the stage.…”

Math, monkeys, and the developing brain

“…The developmental trajectories of the discrimination of other quantities, such as loudness, pitch, pressure, temperature, density, motion, and saturation, have not been tested. However, there is evidence that young children and even infants can form compatible representations across many of these different dimensions (55)(56)(57)(58).…”

How arbitrary is language?

“…However, Ozturk et al [22] demonstrated that four-month-old children have a similar preference, indicating that substantial knowledge about language is not required in order to form these preferences. Similarly, Walker et al [23] showed that three-to four-month-old infants were able to form cross-modal correspondences between spatial height and angularity with auditory pitch, demonstrating that cross-modal correspondence preferences can precede substantial language learning rather than being a consequence of the fact that a particular language instantiates these correspondences [24].…”