Early Word Learning In Neurodevelopmental Disorders: Implications for Eye-Tracking Trajectories In Autism and Fragile X Syndrome

 

Background: Learning words requires that children use adult social cues to make mappings between novel labels and objects (Hollich et al., 2000). Techniques for assessing this process, often termed “fast-mapping,” typically employ in-person assessments that require attention to and behavioral compliance with examiner directions (McDuffie, Yoder, & Stone, 2006). In young males with neurodevelopmental disorders, however, characteristics such as gaze avoidance, social anxiety, and poor response planning may interfere with the assessment of word learning in the context of in-person interactions requiring overt behavioral responses (Dalton et al, 2008; Hessl et al, 2006). By eliminating the need for such responses, eye-tracking methodology in combination with a video presentation of a fast-mapping paradigm may provide a more sensitive and in-depth measure of word learning.

Objectives: The purpose of this study is to compare two approaches to assessing novel word learning in young males with autism, FXS, and typical developmental profiles.  The approaches include: (1) an interactive fast-mapping paradigm during which an examiner presents novel label-object pairings in a teaching phase followed by a testing phase requiring an overt behavioral response from the participant, and (2) a passive eye-tracking version of the interactive paradigm requiring only visual attention to a computer screen.

Methods: Participants are 45 males, 15 each with typical development, autism, and FXS, with groups matched on nonverbal mental age. The eye-tracking task involves a video-recorded presentation of an examiner sequentially introducing four pairs of novel objects to a participant. For each pair, the target object is presented and labeled 5 times in sentence final position, whereas the foil object is talked about in general terms without labeling. The duration of exposure to each object is equivalent. Following exposure to the novel object pair, the child is asked to look at the target object. The outcome measure of the eye-tracking task is the relative duration of gaze to the target object during the comprehension probe.

Results: Preliminary analyses from a subset of the participants suggest that those with typical development, autism, and FXS are significantly different in the percentage of gaze to the target objects during comprehension probes. Specifically, typically developing participants showed the greatest average duration of fixation to target objects, followed by participants with autism. Participants with FXS showed little gaze to the target object during comprehension probes, which may be related to a lack of visual attention to examiner cues during exposure. We will compare these results to those obtained in the interactive-version of the task

Conclusions: A discussion of the fidelity and efficacy of eye-tracking paradigms for assessing socio-cognitive processes will be provided.  Implications for developing targeted interventions for children with ASD and Fragile X Syndrome based on eye-tracking trajectories will be discussed.