Intersensory Redundancy Guides Perceptual Learning: Discrimination of Tempo in 3-Month-Olds * Lorraine E. Bahrick 1 , Robert Lickliter 2 , and Ross Flom 1 1 Florida International University 2 Virginia Polytechnic Institute and State University Department of Psychology Department of Psychology Miami, FL 33199 Blacksburg, VA 24061 Abstract Bahrick and Lickliter (2000) recently proposed an intersensory redundancy hypothesis, which holds that in early development information presented redundantly and in temporal synchrony across two sensory modalities selectively recruits infant attention and facilitates perceptual learning more effectively than does the same information presented unimodally. In support of this hypothesis, we found that 5-month-old infants were able to differentiate between two complex rhythms when they were presented bimodally, but not when presented unimodally. The present study extended our test of the intersensory redundancy hypothesis to younger infants and to the amodal property of tempo. Results replicated and extended those of Bahrick and Lickliter (2000) by documenting that 3-month-old infants can discriminate a change in tempo following bimodal but not unimodal habituation. It appears that when infants are first learning to differentiate an amodal stimulus property, discrimination is facilitated by intersensory redundancy and attenuated under conditions of unimodal stimulation. Introduction Research indicates that infants perceive coherent, unified multimodal objects and events through different sensory modalities even in the first months of life. Little is known, however, about how they achieve such impressive intersensory capabilities at such young ages. We have proposed an “intersensory redundancy” hypothesis as an explanation for how this process could be initiated and guided during early infancy. We argue that when information is presented redundantly and in synchrony across sensory modalities it selectively recruits infant attention, causing amodal stimulus properties (such as duration, tempo, rhythm) to become “foreground” and other stimulus properties to become “background”. Within a given episode, this leads to earlier perceptual processing for properties that are specified in more than one modality. From this view, infants should more easily detect amodal information when it is presented bimodally that when it is presented unimodally. For example, Bahrick and Lickliter (2000) recently showed that 5-month-old infants could differentiate between two five- element rhythms when the rhythms were presented bimodally, but showed no evidence of differentiating the rhythms when they were presented unimodally. The present experiment was designed to further test the generalizability of this aspect of the intersensory redundancy hypothesis by utilizing younger infants (3-month- olds) and assessing their discrimination of a different amodal property, tempo of action, using the same stimuli and procedures as the previous study. It was hypothesized that infants’ detection of tempo would be facilitated under bimodal audio-visual presentations and attenuated under unimodal presentations. Methods Thirty-two 3-month-olds were habituated in an infant-controlled procedure to films of a hammer tapping out a rhythmic sequence in one of two tempos (Tempo 1 = 55 bpm, Tempo 2 = 120 bpm). The same tempo could be * Poster presented at the 2 nd Annual Second Annual International Multisensory Research Conference, Tarrytown, NY, October 6-7 2000. This research was supported by a NIH grant, RO1 HD25669, awarded to the first author and a NIMH grant, K02 MH01210, awarded to the second author. Address correspondences to Lorraine Bahrick: bahrick@fiu.edu Address reprint requests to Ross Flom: flomr@fiu.edu