• Initiating joint attention (IJA)
• Responding joint attention (RJA)
• Joint attention (JA)
• Autism Spectrum Disorder (ASD)
• High Risk -non ASD (HR-nASD)
• Eye tracking

BACKGROUND
Joint attention (JA) is the human ability to coordinate our attention with that of other people. It has been established that joint attention is impaired early in Autism Spectrum Disorder (ASD).
The aim of this eye-tracking study was to evaluate the visual patterns during tasks eliciting responding joint attention and initiating joint attention in High Risk – non ASD (HR-nASD) subjects as compared to ASD and typical development (TD) children.

METHODS
Fifty-two children participated in the study: 17 ASD, 19 HR-nASD and 16 TD. The sample age range was 18-33 months. All subjects enrolled underwent a comprehensive clinical assessment and eye tracking experiments using three tasks: one for responding JA (RJA) and two tasks for initiating joint attention (IJA-1 and IJA-2). Fixations, Transitions and alternating gaze were analyzed.

RESULTS
In the RJA task only the number of transitions from face to non- target object was significantly different between the HR- nASD and ASD subjects (p=0,004) with lower values for the HR-nASD group.
In the IJA1 task alternating gaze between target object and the model’s face was statistically different between HR-nASD and ASD subjects (p<0,001) as well as between TD and ASD subjects (p= 0,029). Alternating gaze between the non-target object and the model’s face and between non-target object and target object differed significantly between the HR-nASD and TD groups (p= 0,012 and p= 0,003, respectively) with lower values for the HR- nASD population.
In the IJA2 task alternating gaze between face and target object differed significantly between HR-nASD and ASD subjects (p <0,001) as well as between the TD and ASD groups (p= 0,004). Moreover, in ASD group reduced alternating gaze between the face and the target object was associated with more core ASD symptoms (p=0,004), in particular social and communicative impairment (p= 0,015).


CONCLUSIONS
Siblings who do not develop later ASD show lower non-verbal cognitive skills than typical development children and similar levels of restricted and repetitive behaviors and better social and communicative skills as compared to ASD children.
During eliciting initiating joint attention tasks, HR-nASD toddlers exhibit visual patterns similar to TD in terms of target-object-to-face gaze alternations, while their looking behavior was similar to ASD toddlers regarding not-target-object-to-face gaze alternations. In ASD reduced alternating gaze target object-to-face is associated with elevated social affect impairment. The study of alternating gaze in typical and atypical development can provide us with valuable information about how children begin to visually explore the world around them and how they share interest in objects and/or events with other people.