15849
Response and Initiative Joint Attention in Toddlers with Autism Spectrum Disorder: An Eye-Tracking Study
Autism Spectrum Disorders (ASD) is well known only from three years of life and further information seems to be necessary regarding the modality of onset in the first two years. Studies on high-risk detected several evolutionary atypical ability that can be considered precursors of ASD. In particular ‘joint attention’ (JA) is a crucial ability for the social development of the child. An atypical functioning of JA in ASD is widely recognized. Up to date JA is mainly assessed using clinical evaluations of behaviour. In this Italian multi-centric study, called ALERT, we used eye-tracking to better characterize JA in toddlers with ASD.
Objectives:
To use eye-tracking technology for the evaluation of JA (response and initiative) in toddler with ASD.
Methods:
A sample of 11 ASD toddlers (9M and 2F; mean age: 21.4 ± 1.6 months) was recruited. Two subjects were excluded because they moved too much during the test and so the amount of data was not enough for the analysis. The test involved the use of video sequences (8 s) and gaze behaviour was measured with an eye-tracker (SMI, RED500). The experiment consisted of three tasks: a response joint attention (RJA) and two initiative joint attention (IJA) tasks. In RJA task a woman is between two identical toys and turns her head and eyes to one of the objects (task 1), in the two IJA task the woman maintains direct gaze but in one case one the object activates unexpectedly (task 2), while in the other one the object appears from one end of the frame and crosses the scene (task 3). Different region of interest (ROIs) were defined: person’s face, eyes, mouth and body, target object and non-target object. For each ROI the fixation count (FC), the first fixation duration (FFD) and the fixation time (FT) were measured. FC and FT were computed as a percentage of the total.
Results:
In all the 3 tasks FC and FFD were increased for the face with respect to the other ROIs. In task 2 also FT was increased for the face with respect to the other ROIs. No other significant differences were present among the different ROIs within each task. Comparing the different tasks we observed an increased FC in task 2 vs task 1 for target object (p=0.02) and non-target (p=0.03) an increased FT for target object in task 2 vs task 1 (p=0.015) and vs task 3 (p=0.004) and an increased FT for non target object in task 2 vs task 1 (p=0.04).
Conclusions:
The protocol developed appears effective in characterizing gaze during JA tasks. The children seem to be more attractive by the objects in the task 2 although they do not distinguish so much between the target and other objects. A longitudinal study could allow to better understanding the evolution of JA ability in children with ASD.