Effect of speaker gaze on word learning in fragile X syndrome: a comparison with nonsyndromic autism spectrum disorder.

PURPOSE: This study examined use of a speaker's direction of gaze during word learning by boys with fragile X syndrome (FXS), boys with nonsyndromic autism spectrum disorder (ASD), and typically developing (TD) boys. METHOD: A fast-mapping task with follow-in and discrepant labeling conditions was administered. We expected that the use of speaker gaze would lead to participants selecting as the referent of the novel label the object to which they attended in follow-in trials and the object to which the examiner attended in the discrepant labeling trials. Participants were school-aged boys with FXS (n=18) or ASD (n=18) matched on age, intelligence quotient, and nonverbal cognition and younger TD boys (n=18) matched on nonverbal cognition. RESULTS: All groups performed above chance in both conditions, although the TD boys performed closest to the expected pattern. Boys with FXS performed better during follow-in than in discrepant label trials, whereas TD boys and boys with ASD did equally well in both trial types. The type of trial administered first influenced subsequent responding. Error patterns also distinguished the groups. CONCLUSION: The ability to utilize a speaker's gaze during word learning is not as well developed in boys with FXS or nonsyndromic ASD as in TD boys of the same developmental level.

Effects of labeling and pointing on object gaze in boys with fragile X syndrome: an eye-tracking study.

We examined the visual processing of a social learning stimulus and the ways in which visual attention was distributed to objects as well as to the examiner's face during word learning under conditions that varied only in the presence or absence of a label. The goal of the current study, then, was to evaluate the effects of differentially providing pointing and labeling during exposure to a novel target object in males with fragile X syndrome (FXS) (n=14, ages 4.33-10.02), autism spectrum disorder (ASD) (n=17, ages 4.04-10.4), or typical development (TD) (n=18, ages 2.05-5.33). In particular, the present study examined attention to the examiner's face as well as target and distracter objects that were presented as video stimuli. An eye-tracker captured gaze to the video stimuli as they were shown in order to examine the way in which children with FXS, ASD, or TD distributed their gaze toward the examiner and the objects. Results indicated that no group showed increased gaze toward the target object compared to the distracter object. However, results revealed that participants with FXS showed significantly increased face gaze compared to the novel objects, whereas children with ASD and TD both showed similar amounts of relative gaze toward the face and objects. Furthermore, the act of pointing at the target object was found to increase gaze toward the target objects compared to when there was no pointing in all groups. Together, these findings suggest that social cues like those employed in a word-learning task, when presented with video, may relate to gaze in FXS in context- or task-dependent ways that are distinct from those expected during live interaction.