Poster #164 - Longitudinal Development of Intersensory Perception to Social and Nonsocial Events From 6-24 Months of Age

• In Event: 2-163 - Poster Session 08
  In Poster Session: PS 08 Section - Perceptual, Sensory, Motor

Integrative Statement

Intersensory processing, coordinating redundant stimulation across multiple sensory modalities (e.g., audiovisual speech), guides attention to unitary multimodal events and provides a foundation for language and social development (Bahrick & Lickliter, 2012). Intersensory processing develops rapidly across infancy. However, until recently, the development of intersensory skills has been characterized by group-level data (e.g., intermodal preference, habituation). Thus, relative competencies of individual children and developmental pathways to outcomes remain poorly understood. We developed the Intersensory Processing Efficiency Protocol (IPEP; Bahrick et al., 2018) to assess this gap. The IPEP indexes fine-grained individual-differences in intersensory processing of social and nonsocial events. Here, using the IPEP, we explore developmental change in intersensory processing speed and accuracy for both social and nonsocial events across the first two years of life.
The IPEP was administered to 95 infants longitudinally at 6, 12, 18, and 24 months of age. On each of the 48 8-s trials, infants view a 2x3 grid of 6 dynamic visual events of women speaking (social events) or objects impacting a surface (nonsocial events; see Figure 1). One of the events is synchronous with its natural soundtrack (target event), and the other five events are asynchronous with the soundtrack. Eye-tracking (Tobii X120) is used to derive two measures of accuracy: (1) how often infants find the target (proportion of trials on which the target was fixated – PTTF) and (2) how long infants look to the target (proportion of total looking time to the target – PTLT), and one measure of speed: how quickly infants locate the target (reaction time – RT).
We assessed longitudinal trajectories of all three measures (PTTF, PTLT, and RT) using SEM-based latent growth curve modeling. For social events, PTTF, PTLT, and RT all exhibited significant quadratic increases across age (see Figure 2). All models exhibited good model fit (X2s range: .712-6.16, ps>.13) and significant improvement in model fit relative to no-growth models (X2¬¬difference range: 10.75-39.40, ps<.05). For nonsocial events, PTTF exhibited significant linear growth across age; moderate model fit, X2=16.13, p<.01; but significant model improvement relative to the no-growth model, X2difference=14.45, p=.006. In contrast, models assessing nonsocial PTLT and RT showed poor model fit.
Findings provide the first longitudinal trajectories characterizing the development of speed and accuracy of intersensory processing across the first two years of life. Developmental change was evident for social events, whereas evidence of change for nonsocial events was mixed. For social events, both measures of accuracy showed developmental improvement. In contrast, for nonsocial events, only one measure of accuracy (how often infants found the target) showed developmental change, whereas the other (how long infants looked at the target), showed no evidence of change. Interestingly, intersensory processing speed for social events decreased across age with slower speeds at older ages. This may reflect the use of different task strategies across age. In contrast, speed for nonsocial events showed no evidence of change. Future research will assess relations between individual trajectories and developmental outcomes that rely on a multisensory foundation (e.g., language and social functioning).

Authors

• Myriah E McNew, Florida International University
  Presenting Author

• James Torrence Todd, Florida International University
  Non-Presenting Author

• Lorraine E Bahrick, Florida International University
  Non-Presenting Author