From jumbled sounds and sights to higher-order processes: investigating audio-visual Sensitivity to Intersensory Synchrony and its influence on Executive Functions, Self-Regulation, and Language in typical and atypical preschool development

Sensory integration is increasingly acknowledged as a crucial factor in the development of cognitive and social abilities. This dissertation aimed to contribute to this understanding by investigating preschoolers’ Sensitivity to Intersensory Synchrony - a foundational ability that guides sensory integration by enabling the detection of cross-modal redundancies through temporal proximity. A total of 396 children aged 3 to 5 years (305 neurotypicals, 55 with Developmental Language Disorder, and 36 with a history of Childhood Maltreatment) participated in this research. Using an eye-tracking preferential looking task, this series of studies examined Sensitivity to Intersensory Synchrony in both typical and atypical development in response to audiovisual speech stimuli, exploring its profiles, its age-related changes, as well as its malleability across groups and in response to different formats of perceptual training (both single- and multiple-session) which included simple, playful, and engaging activities aimed at actively involving children in experiencing and reproducing multisensory synchrony. The research also sought to uncover whether and how Sensitivity to Intersensory Synchrony promotes higher-order processes crucial for future development, such as Language, Executive Functions, and Self-Regulation. The data revealed a more refined Sensitivity to Intersensory Synchrony in typical development than previously reported, alongside specific alterations in each group with atypical development. Additionally, the results highlighted a foundational role of Sensitivity to Intersensory Synchrony in sustaining the development of the investigated higher-order processes. Signs of malleability and enhancement through perceptual training were observed across groups, even after a single session as well as, in typical development, potential to generate positive bottom-up virtuous cycles through multiple-session training, enhancing Self-Regulation and Executive Functions by building on their embodied foundations in Sensitivity to Intersensory Synchrony. However, a more complex and dynamic framework emerged than initially expected, with non-linear trajectories and dynamic rebalancing that warrant further investigation. While these findings require further confirmation and expansion, this research provides an initial theoretical framework and a practical tool to support the development of basic perceptual mechanisms, which are increasingly recognized as key determinants of lifelong outcomes.