Document Type



Doctor of Philosophy (PhD)



First Advisor's Name

Lorraine E. Bahrick

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Eliza Nelson

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Shannon Pruden

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Jacqueline Lynch

Fourth Advisor's Committee Title

Committee member


intersensory processing, audiovisual speech, individual difference measures, language outcomes

Date of Defense



Intersensory processing (e.g., matching sights and sounds based on audiovisual synchrony) is thought to be a foundation for more complex developmental outcomes including language. However, the body of research on intersensory processing is characterized by different measures, paradigms, and research questions, making comparisons across studies difficult. Therefore, Manuscript 1 provides a systematic review and synthesis of research on intersensory processing, integrating findings across multiple methods, along with recommendations for future research. This includes a call for a shift in the focus of intersensory processing research from that of assessing average performance of groups of infants, to one assessing individual differences in intersensory processing. Individual difference measures allow researchers to assess developmental trajectories and understand developmental pathways from basic skills to later outcomes. Bahrick and colleagues introduced the first two new individual difference measures of intersensory processing: The Multisensory Attention Assessment Protocol (MAAP) and The Intersensory Processing Efficiency Protocol (IPEP). My prior research using the MAAP has shown that accuracy of intersensory processing at 12 months of age predicted 18- and 24-month child language outcomes. Moreover, it predicted child language to a greater extent than well-established predictors, including parent language input and SES (Edgar et al., under review)! Manuscript 2 extends this research to examine both speed and accuracy of intersensory processing using the IPEP. A longitudinal sample of 103 infants were tested with the IPEP to assess relations between intersensory processing at 6 months of age and language outcomes at 18, 24, and 36 months, while controlling for traditional predictors, parent language input and SES. Results demonstrate that even at 6 months, intersensory processing predicts 18-, 24-, and 36-month child language skills, over and above the traditional predictors. This novel finding reveals the powerful role of intersensory processing in shaping language development and highlights the importance of incorporating individual differences in intersensory processing as a predictor in models of developmental pathways to language. In turn, these findings can inform interventions where intersensory processing can be used as an early screener for children at risk for language delays.



ORCID 0000-0003-4419-1876

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Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.



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