Effects of Social and Non-Social Cues On Saccadic Eye Movements in ASD and ADHD

Background: Information gained from another person’s eyes plays a crucial role in social communication. People with autism have difficulty following gaze in naturalistic and semi-naturalistic situations. Children with ADHD also exhibit behavioral difficulties with social interaction, although it is unclear whether their problems arise from substrates similar to those with ASD. It has been suggested that poor social behaviors in ASD are related to deficits in social perception, while in ADHD they are associated with inattention and impulsivity. Recently, the attentional mechanism corresponding to reflexive orienting towards the direction of others’ eye gaze was assessed using the Posner-style spatial cueing paradigm. Evidence that people with autism can reflexively orient their attention in response to eye gaze cues is contradictory. Although some studies have demonstrated apparently normal effects of social cueing, the results of other experiments suggest that people with autism respond to social cues such as eye gaze in much the same way as they do to non-social cues such as arrows, whereas in non-autistic people, a greater salience to social cues has been reported.
Objectives: Studies comparing the ASD group with other neuropsychiatric disorders are lacking. This study uses an eye-tracker to investigate social attention comparing pure ASD and ADHD groups for the first time with a group of co-morbid ADHD&ASD.
Subjects & Methods: Boys aged 7 to 16, with diagnosis of pure ADHD, pure ASD or comorbid ASD+ADHD (FSIQ>70) were tested on a cueing paradigm. Participants were instructed to shift their gaze to the peripheral target that appeared on either side of a visual fixation point. Before the target appeared, a centrally presented stimulus (eye gaze or arrow) cued the participant to the correct or incorrect side. The cue was predictive (i.e. congruent) only in 50% of trials.
Results: Results of 13 ADHD, 7 ASD & 8 co-morbid subjects (age and FSIQ matched) are reported with data collection still in progress. Saccadic reaction times were analysed using repeated measures analysis of variance with group as between-subject factor and cue (arrows versus eyes) and congruency (congruent versus incongruent) as within-participant factors.
There were no group effects, and no significant group by cue interaction. The group by congruency interaction approached significance (p=0.054). In the ASD group the SRT for incongruent condition was significantly faster than the congruent condition (p=0.01) whilst both ADHD and comorbid groups were significantly slower in incongruent than congruent conditions (p=0.04 and p=0.007; respectively). The congruency by cue interaction was also significant (p=.047) suggesting longer reaction times with congruent than incongruent cues in the arrow but not the face condition.
Conclusions: Reaction time facilitation for the congruent conditions was seen in the ADHD and co-morbid groups but not in the ASD. This pattern points to a dissociation of the clinical groups at the level of attentional cue processing and it seems as if the ASD participants didn’t acknowledge the salience of cue. The comparison of the data with a control group will enable us to better explain the different patterns of social attention in theses clinical groups.