[PS-2.13]Infants' physiological responses to cross-modal touch+speech input

Abu-Zhaya, R. , Tonnsen, B. , Francis, A. & Seidl, A.

Purdue University

Infants use transitional probabilities to detect patterns in unimodal input (Saffran et al., 1996), and touch+speech (Seidl et al., 2015), but not visual+speech input (Seidl et al., 2015; Thiessen, 2010). That infants track transitional probabilities from touch+speech better than from visual+speech input might be the result of the salient nature of touch or infants? early sensitivity to touch (which develops at 21 weeks in utero), both of which could help garner infants? attention and aid learning. Physiologically, infants respond to touch with heart-rate deceleration (Fairhurst et al., 2014), an index of infants? attention (Richards & Casey, 1991). We examined heart-activity as an index of infants? attention in tracking statistics and hypothesized that attention to touch+speech stimuli would vary depending on cross-modal transitional probabilities.
Fourteen 5-month-olds were presented with a continuous stream of syllables with no boundary cues while an experimenter delivered timed touches to two body-parts. Touches were either redundant or non-redundant with speech. Results revealed an effect of redundancy; infants showed greater heart-rate deceleration following redundant touch+speech events compared with non-redundant ones. Results are consistent with literature showing heart-rate deceleration during sustained attention (Richards & Casey, 1991) suggesting that attention may mediate infants? ability to perform cross-modal statistical learning.