Cooper, R.P, & Richards, J.E. (2002). Differential heart-rate activity in infants to uni- and multimodal events. Society for Research in Child Development, Tampa, FL. (PDF)
This investigation compared visual and heart-rate defined attention in infants to multimodal displays. To date, 37 infants (14 to 26-weeks-old) saw and/or heard 9 events (twice, for a total of 18 trials) in a semi-random sequence: (1) visual only (geometric form, adult-directed face, infant-directed face), (2) auditory only (music, AD voice, ID voice), and (3) visual+auditory (geometric form+music, AD face+voice, ID face+voice). ECG was recorded using Ag-AgCl electrodes and digitized at 1 KHz. Interbeat intervals were calculated during prestimulus and poststimulus periods (for each trial). Trial duration was determined by two successive periods of HR deceleration/acceleration, or 60 seconds (whichever came first). There was a significant effect of event type on percent HR deceleration/trial length (F(8, 566)=2.09, p<.04), with the longest decelerations on ID face+voice trials (M =.65,SD=.23). This measure was < .60 for the other stimulus events. Also, a significant main effect of event type on percent visual attention/trial length was found (F(8,652)=11.81,p<.001), with the largest amount of looking on geometric+music trials (38%) and ID face+voice trials (36%) compared to all other stimulus events. Although infants looked the least on auditory alone trials (all < 20%), they were as attentive (defined by HR deceleration) on these trials as to visual alone. These results suggest that visual and auditory events are not equal in their ability to direct and maintain infants’ attention, with most attention generated by female ID multimodal interactions.