Relations Among Speed of Attention Shifting, Background Noise, and Symptom Severity in Children with Autism Spectrum Disorders

Background:  Children with autism spectrum disorders (ASD) show impaired attention and intersensory processing skills compared with typically developing (TD) children (Bebko et al., 2006; Bahrick & Todd, 2012). They show difficulty disengaging attention (Landry & Bryson, 2004; Todd & Bahrick, 2010) and integrating audiovisual speech in the presence of background noise (Smith & Bennetto, 2007). Findings suggest impairments in ASD are enhanced in the context of competing auditory or visual stimulation. 

Objectives:  We investigated whether competing background noise would degrade speed of attention shifting in children with ASD to a greater extent than for TDs.  Disengagement (shifting away from competing stimulation to a peripheral event) and orienting (shifting in the absence of competing stimulation) were assessed using the Multisensory Attention Assessment Protocol (MAAP; Bahrick et al., 2011). We predicted that, compared to TDs, children with ASD would show greater impairments in disengagement and orienting when background noise was present vs. absent. We also predicted that greater impairments in attention shifting would correlate with higher symptom severity in ASD.

Methods:  Children with ASD (N=21; M=4.23 years, SD=.86), who passed ADOS cutoffs, and TD children (N=21; M=2.47, SD=.50), matched on Mullen adjusted age (ASD: M=2.47, SD=1.37; TD: M=2.77, SD=.77) participated. In the MAAP, trials of a 3s central visual event were immediately followed by two side-by-side peripheral events (10s), one moving in synchrony with its natural soundtrack, were presented. Peripheral events consisted of social (two woman speaking) and nonsocial events (two objects striking a surface) and were presented with and without background noise. Disengagement (RT to shift to a peripheral event while the competing central event was on) and orienting (RT to shift to a peripheral event after the central event went off) were assessed.  ADOS Standard Scores indexed symptom severity (see Gotham et al., 2009).

Results:  Children with ASD showed longer RTs on noise than no noise trials (p<.03), whereas RTs for TDs did not differ as a function of noise. ASDs showed longer RTs to disengage and orient than TDs (ps<.01); however, this pattern was more extreme during noise trials. On noise trials, ASDs showed longer RTs for both disengaging and orienting than TDs (ps<.02). In contrast, on no-noise trials, ASDs showed longer RTs to disengage (p=.01) than TDs, but RTs to orient did not differ from TDs. Finally, longer RTs to disengage and orient on noise (but not no noise) trials predicted higher ADOS Standard Scores (rs>.54, ps<.01) in ASDs.

Conclusions:  Children with ASD show significant decreases in speed of disengaging and orienting attention to social and nonsocial events in the presence of noise.  Moreover, noise enhances impairments in ASD relative to TD children, but has little effect on speed of attention shifting in TD children. Further, greater impairments in shifting attention are correlated with higher symptom severity in ASD.  Findings extend research indicating impaired attention skills in ASD (Landry & Bryson, 2004; Todd & Bahrick, 2010) and suggest that these impairments will be most evident under conditions of competing stimulation from background noise.