The aim of this project was to determine the impact of early speech and language experience on language processing and neural representation. In this project, I have studied hearing infants of Deaf signing mothers in comparison to monolingual and bilingual hearing infants of hearing mothers. I have collected behavioural, eye-tracking and neuroimaging data from 99 4-to-8 month old infants from 3 groups: monolinguals, unimodal bilingual and bimodal bilinguals. Here is a brief description of the data collected in this project. Mullen Scales of Early Learning: A standardised developmental assessment of receptive and expressive language, visual reception, dexterity and gross motricity. Each infant was assessed by a trained experimenter and each assessment was filmed for off-line coding. Parent-Child Interaction: Parents were asked to 'play with their baby as they would do at home'. Interactions were filmed for off-line coding of attachment and communication in each parent-infant dyad. This project aims to determine the impact of early speech and language experience on language processing and representation in the brain. It will study hearing infants of deaf mothers who use a sign language as their dominant language (HoD infants) in comparison to hearing infants of hearing mothers (HoH infants). Despite normal hearing, HoD infants have a different early experience of speech and language to that of HoH infants. First, since deaf signing mothers are less likely to use auditory speech than hearing mothers, their infants are likely to have reduced exposure to auditory spoken language. Second, the experience of HoD infants includes both a language in the visual modality, eg British Sign Language (BSL), and one in the auditory modality, eg English. Since HoD infants are exposed to two languages, they will be compared to HoH individuals who are exposed to two spoken languages. This project will use near infrared spectroscopy and eye-tracking to test the hypothesis that the experience of HoD infants influence their neural representation of language, their patterns of eye gaze during spoken and signed language perception and their audio-visual speech integration.

Eye-tracking protocol: Each infant was filmed during the presentation of the 3 eye-tracking tasks and their eye movements were recorded using a Tobii eye-tracker. 1- Face pop-out: This task assesses face orientation. Slides with a face, a scrambled face, a phone, a bird and a car are presented to infants in order to measure the relative time spent looking at faces versus other objects and the direction of each infant's first gaze. 2- Gaze following: This task assesses infants' ability to follow a model's gaze to an object of interest. In each video, the model first attracts the infant's attention and then shifts gaze to one of two objects. Video and eye-tracking data are used to determine whether the infant followed the model's gaze, and data is compared across two different means of attracting attention: eye contact and infant directed speech. 3- McGurk: This task assesses the infants' gaze movements during the presentation of syllables articulated with congruent, incongruent or no sound track. Video and eye-tracking data are analysed to determine the infant's sensitivity to audiovisual speech incongruences. NeuroImaging data: This task assesses infants' brain representation for language. Infants are presented with audiovisual videos of models telling short story extracts in different languages, while brain activation is measured using functional Near Infrared Spectroscopy (fNIRS). Video and neuroimaging data are analysed to compare the neural representation of spoken and signed languages, as well as familiar and unfamiliar languages in each group of infants. Questionnaires: 1- Family Information (4-8 months): A short questionnaire reporting details of the pregnancy and birth, the infant's health, family composition and socio-economic status. 2- Language exposure (4-8 months): A questionnaire detailing bilingual infants' exposure to each of their languages 3- Language mixing (4-8 months): A questionnaire detailing the use of language mixing practices in bilingual mothers 4- Family information - 14 months update and 24 months update: A short questionnaire reporting details of the child's health, language exposure and development 5- Communication Development Inventory : Questionnaires sent at 14 and 24 months detailing language development in each of the child's languages. 6- Infant Sensory Profile (14 months): A questionnaire detailing a children's patterns of sensory processing 7- Early Childhood Behavior Questionnaire (24 months): A questionnaire describing a child's behavior in different context with an aim to clarify the child's temperament.