The Relationship Between Repetitive Behaviors and Executive Function in Children with Autism Spectrum Disorder

Background: It has been hypothesized that the manifestation of repetitive behaviors and restricted interests in individuals with ASD may be related to impairments in executive function. Past attempts to validate this theory, however, have yielded mixed results. Prior studies that have utilized broad measures of executive functioning (e.g., Wisconsin Card Sorting Task) have generally yielded positive results; whereas studies that employed measures thought to primarily tap an isolated component of executive functioning often fail to find a relationship with repetitive behaviors.  One possible explanation is that ASD-related impairment in executive function and its relationship to repetitive behaviors may be most evident in situations in which concurrent demands are placed on multiple aspects (e.g., inhibitory control, task switching) of executive function.

Objectives: The goal of the present study was to test the hypothesis that the presence of secondary executive demands (e.g., task switching needs) would mediate the relationship between laboratory-measured inhibitory control and day-to-day manifestations of repetitive behaviors.

Methods: A sample of 22 children (mean age: 14.4 years, SD = 2.4) with high functioning (IQ >70) ASD completed an antisaccade eye movement task.  In this task, participants were presented with a central fixation point flanked to the far left and right by peripheral boxes.  After a short delay, the fixation point was replaced briefly with a colored symbol (e.g., a red X or green O) followed by a brightening of one of the peripheral boxes.  Importantly, the colored symbol indicated whether the participant should look towards the subsequent brightened box (a prosaccade) or away from it (an antisaccade).  Participants completed 20 practice trials, followed by 192 experimental trials.  Trial types were intermixed thus resulting in 4 critical conditions: (1) ‘Baseline’ trials associated with minimal executive demands = prosaccade trial that follows another prosaccade trial, (2) ‘Inhibition Only’ trials associated with inhibitory but not switching demands = antisaccade trial that follows another antisaccade trial, (3) ‘Switching Only’ trials associated with switching but not inhibitory demands = prosaccade trial that follows an antisaccade trial, and (4) ‘Inhibition+Switching’ trials associated with both inhibitory and switching demands = antisaccade trial that follows a prosaccade trial.  The severity of repetitive behavior symptoms exhibited by participants was assessed using the Repetitive Behavior Scale (RBS; Lam & Aman, 2007).

Results: Data was analyzed using a multiple regression approach.  Performance in the combined Inhibition+Switching condition of the antisaccade task explained a significant portion of variance in repetitive behavior symptomatology (as measured by the RBS), ΔR²=.19; ΔF(1,17)=5.4; p=.03.  In contrast, performance in the Inhibition Only condition and Switching Only condition explained little variance in RBS score, ΔR²<.07; ΔF(1,17)<1.5; p>.24 in both instances.

Conclusions: Consistent with our hypothesis, the relationship between day-to-day manifestation of repetitive behaviors and our laboratory test of executive function was evident only when concurrent demands were placed on more than one aspect of executive function (i.e., both inhibitory control and task switching).  This research represents a promising step towards understanding (and bridging) the gap between the laboratory-based assessment and everyday functioning.