Effects of Multisensory Stimulation on Infants’ Processing and Learning

The research reported here investigated how the congruency of audiovisual stimulation affects infants' perceptual processing and learning. The research questions addressed were based on the Intersensory Redundancy Hypothesis (IRH; Bahrick & Lickliter, 2000, 2002, 2012). This theory states that certain kinds of stimulation (i.e., intersensory redundancy) drive infants' attention to specific object/event properties. The first study examined the effect of audiovisual stimulation on 10-month-old infants' encoding of object pattern. Since the results were inconclusive, the following experiment used a different set of visual stimuli. The second study found that the type of audiovisual stimulation that 10-month-old infants received did not affect their learning of object pattern. The third study examined whether younger infants, such as 4- and 6-month-olds, would be affected by the multisensory nature of stimulation. The experiment revealed that only the 6-month-old infants encoded the visual object pattern, and the effect was more robust when they received only visual stimulation. The fourth study extended these findings and showed that, contrary to the predictions of the IRH, 6-month-old infants learn both the pattern and the trajectory of objects when they receive congruent audiovisual stimulation. The final study investigated the effect that audiovisual gender matching on 6-month-old infants' perception of audiovisual speech synchrony. It revealed that, in the gender congruent condition, the infants looked longer at a video of a person who spoke in synchrony with a voice recording. This finding is inconsistent with the IRH and suggests that arbitrary cross-modal relations influence infants' responses to intersensory redundancy. Altogether, the results provide partial support for the IRH in indicating that infants' perception and learning is affected by multisensory stimulation. They also highlight some limitations of the IRH and directions for further research.