The Effect of Target Saliency on the Disengage Deficit in a Reaching Task in Autism Spectrum Disorder

Background: It is widely reported that persons with Autism spectrum disorder (ASD) have disordered visual attention, in that they tend to continue looking at a target long after typically developing peers look away (i.e., a ‘disengage deficit’). During toy play, toddlers at high-risk (HR) of ASD (i.e., with an older sibling diagnosed with ASD) show a disengage deficit when grasping toys (Sacrey et al., 2013). Interestingly, resent research has noted that target saliency may impact visual attention patterns of persons with ASD (Freeth et al., 2011), raising the question of whether saliency may influence disengagement of attention in HR infants.

Objectives: To determine if target saliency affects latency to disengage visual attention in HR infants during a reaching and grasping task.

Methods: Participants: Three groups of toddlers: (1) HR siblings who did not receive an ASD diagnosis at 36 months (HR-N), (2) HR siblings who did receive a diagnosis of ASD at 36 months (HR-ASD), and (3) toddlers without a family history of ASD (low-risk; LR).

Task: LR and HR were filmed at 18, 24, and 36 months of age as they engaged in play with small, easily graspable toys (high visual saliency) or ate small, easily graspable food items (low visual saliency). Duration of time spent looking at targets before moving the hand towards the target (engaging attention) and the duration of time spent looking at the target after grasp (disengaging attention) were measured and transformed into percentage of time.

Diagnostic Assessment: At 36 months of age, an independent diagnostic assessment for ASD (including ADOS, ADI-R and clinical judgment based on DSM-IV-TR) was completed for all participants.

Statistical Analyses: A 3 (Group: LR, HR-N, HR-ASD) x 3 (Age: 18, 24, 36 months of age) x 2 (Target: toy, food) repeated measures ANOVA was completed on measures of engaging attention and disengaging attention.

Results: For engaging attention, the HR groups spent more time staring at the target than LR before reaching towards it (HR-ASD=19.8%; HR-N=12.8%; LR=4.3%; ps<0.0167). There were no target effects; that is, percentage of time looking at the target prior to reaching did not differ between the toy and food targets (14.5% versus 10.7%, respectively). For disengaging attention, the HR-ASD spent more time staring at the target than the LR group (HR-ASD=23.3%; HR-N=13.7%; LR=2.9%; p=0.001) following grasp. In addition, the LR (22.3%; p=0.002) and HR-N (19.5%; p=0.006) groups were more likely to disengage from the target at tactile contact than was the HR-ASD (8.4%) group. There was a target effect, in that all groups were more likely to continue looking at a toy target following grasp than a food target (17.2% versus 9.5%, respectively; p=0.002).

Conclusions: The results suggest that target saliency does not have an ASD-specific effect on engaging and disengaging visual attention during reaching for food and toys in LR and HR toddlers.  As such, the disengage deficit present in HR-ASD toddlers may serve as an early behavioural marker for ASD.