“Scattered Attention” in Face Perception: The Case of Co-Morbid ASD+ADHD

Background: Early atypical attention to faces in ASD is hypothesized to lead to downstream effects on social cognition, causing impairment in everyday social interaction. Although some research using infrared eye tracking paradigms suggests reduced attention to faces (particularly the eye region) in ASD versus typical development, many other studies find no effects. These null results may partially result from small sample sizes and significant within-group heterogeneity in ASD (e.g., high rates of co-morbid ADHD that likely affect gaze patterns). To our knowledge, large-scale eye tracking studies of ASD plus co-morbid ADHD do not exist in the literature.

Objectives: Compare large samples of children with ASD+ADHD vs. ASD alone on an eye-tracking metric of “scattered visual attention” to faces and objects, as well as eyes and mouths.

Methods: Children with ASD (N=125) and ASD+ADHD (N=110) watched 3 16-second sets of 4 video clips, 1 in each quadrant of a 32-inch screen, while their gaze data was collected at a rate of 60 Hz using a Tobii X120 system. Groups did not differ on sex-ratio, age (mean=10y), or IQ (mean=103; all participants >70). Each set of videos included 2 naturally moving neutral faces and 2 moving objects (e.g., car on highway). Areas of interest (AOI) included faces, objects, eyes, and mouths. The number of visits made to faces vs. objects and eyes vs. mouths were compared between diagnostic groups using omnibus repeated measures ANOVA with planned t-tests to determine directionality.

Results: Overall visual attention to the screen did not differ by group (t=-.08, p=.93). An index of “scattered attention” (visit count to the four screen quadrants) was significantly higher in the ASD+ADHD group than the ASD alone group (t=3.24, p=.001). A 2x2 repeated measures ANOVA on visit count with Stimulus (face, object) as a repeated measure and Group (ASD, ASD+ADHD) as a factor revealed a main effect of Group (F=10.48, p<.001, η_p²=.04) and no Group x Stimulus interaction. A similar ANOVA focused within the face with Stimulus (eyes, mouth) as a repeated measure revealed a main effect of Group (F=7.16, p=.008, η_p²=.03) and a Group x Stimulus interaction (F=4.17, p=.04, η_p²=.02). Planned t-tests revealed that the ASD+ADHD group looked more frequently at the eyes than the mouth, whereas the ASD only group did not, and this translated to longer raw time spent on the eyes in the ASD+ADHD group than the ASD group (all ps<.05).

Conclusions: Children with ASD and ADHD attend to faces differently than those with ASD alone, focusing relatively more on the eyes, and they are significantly more active in their exploration of visual information. This might represent ADHD-driven “scattered attention” or other fundamental differences between the ASD groups, such as decreased social motivation in those with ASD alone. Ongoing analyses are exploring these hypotheses, as well as relationships to face recognition ability and neural representations measured with fMRI (e.g., FFA activation).