Cognitive Control Deficits in Individuals with Differing Levels of Autistic Traits

Abstract

Deficits in inhibitory control are common in Autism Spectrum Disorders (ASD) and are associated with higher levels of repetitive behaviours. Inhibitory deficits may present as an inability to stop a prepotent motor response (reactive inhibition), or as an inability to delay a response onset before it is performed (proactive inhibition). Previous studies have found conflicting results in reactive inhibition deficits in children with ASD indicating heterogeneity in stopping ability, while limited research into proactive inhibition has demonstrated more consistent deficits. This study aims to explore deficits in both types of inhibition in individuals from the general population with differing levels of autistic traits, by comparing two tasks measuring proactive and reactive inhibition. A Stop Signal Task (SST) and reinforcement learning task were administered to 152 participants (18-81 years). Level of autistic traits was measured using the AQ-28 scale. Stop Signal Reaction Time (SSRT) (an index of reactive inhibition) and post-error slowing (a measure of proactive inhibition) were examined in the SST, while another measure of proactive inhibition (reaction time between trials of high and low conflict) was obtained from the reinforcement learning task. Results indicated no significant deficits in both reactive and proactive inhibition regardless of self-reported autistic trait level. A modest interaction effect between age and SSRT predicted Routine subscale score on the AQ-28, suggesting that repetitive behaviour level can be altered by reactive inhibition ability changes across the lifespan. Cognitive control deficits in ASD therefore may be related to factors outside of response inhibition alone.