Objectives: The current study aimed to assess the ecological validity of an eye-tracking assessment of RJA by administering the ESCS and eye-tracking RJA to 39 eighteen-month infant siblings of autistic children, a sample therefore at heightened risk for diagnosis (Bailey et al., 1993). Relationships between both RJA measures and concurrent language scores were assessed. We predicted that both assessments of RJA would be correlated, and would be related to language skills.
Methods: During eye-tracking RJA, each infant watched a video of a model fixating 1 of 2 objects with direction of turn counterbalanced across trials. Eye movements were recorded with a Tobii 1750 eye tracker. Each trial consisted of a baseline phase, an infant-directed greeting and smile, and the model turning and fixating an object for 5 seconds. RJA was calculated by summing the duration of all looks from the model’s face to the correct object relative to the duration of looks from the face to either object. The ESCS yields two measures of RJA: a distal task wherein the examiner visually orients and points towards a poster and a proximal task wherein the experimenter points to pictures in a book directly in front of the infant. Language was assessed with the Mullen Scales of Early Learning. Total scores on the Autism Diagnostic Observation Schedule were used as an index of symptomatology
Results: The eye-tracking RJA was correlated with RJA during the distal ESCS task (p(39)=0.33, p<0.05) but not the proximal task. Only RJA during the proximal ESCS task was positively correlated with expressive (p(36)=0.51, p<0.01) and receptive language scores (p(36)=0.37, p<0.05). When we controlled for autistic symptomatology, eye-tracking RJA and RJA–ESCS-distal remained correlated (r(31)=0.49, p<0.01); and RJA-ESCS-proximal was correlated with eye-tracking RJA (r(31)=0.45, p<0.01) and expressive language (r(31)=0.57, p<0.01).
Conclusions: While eye-tracking RJA and ESCS RJA appear to measure a similar construct, only proximal ESCS RJA related to language. The current study establishes the construct validity of eye-tracking RJA and suggests that it may provide a useful prognostic tool for assessing autism risk.
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