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When we communicate with others, we use a variety of abilities to facilitate and enable that communication. These abilities range from being responsive to others’ communicative cues to making one’s own communication more functional. Such facilitators of communication has been suggested as atypical in the development of autism. Reduced infant responsiveness towards communicative cues ­– such as speech sounds and direct gaze – have been suggested as precursors of autism. Pragmatic language use – to use language in a functional way in social interaction – is considered a core aspect of the condition later in development.

In this thesis, I used diverse methodologies to study the association between these facilitators of communication and autism early in life, utilizing an infant sibling study design. In Study I, basic attentional responsivity to social and non-social sounds in infancy was tested using pupillometry. Responsivity to the non-social sounds, but not the social sounds, differentiated infants with and without subsequent autism. In Study II, infants’ behavioural responsivity to others’ direct gaze was tested in real-life interaction. Neither how much nor how quickly the infants looked towards the other person’s face after the direct gaze was reliably linked to later autism. Lastly, in Study III, two-year-olds use of pragmatic language was assessed with caregiver-questionnaires. We found a specific association between emerging pragmatic language use and dimensional autism already this early in life. 

The findings of this thesis suggest that infant responsivity to speech and direct gaze are not clear precursors of autism. Yet, the emerging ability to use pragmatic language seem to be linked to autism already by two years age. This thesis thus contributes to the understanding of early development of autism and how it relates to responsivity to, and use of facilitators of communication during the first years of life.