Past research has demonstrated relatively intact response inhibition in individuals with autism spectrum disorders (ASD). Response inhibition studies using the Go/NoGo paradigm typically use letters and simple shapes as stimuli. However, several Go/NoGo studies use emotional facial expressions as stimuli in order to explore the influence of social content on response inhibition. Only one study has implemented the Go/NoGo task in ASD using facial emotions, which were limited to anger and happiness (Geurts, Begeer, & Stockmann, 2009). While the study failed to demonstrate differential response inhibition between children with ASD and typically-developing controls (TYP), it is unknown if these findings generalize to additional negative facial expressions, such as sadness and fear, which several studies show to be atypically processed by individuals on the autism spectrum.
Objectives:
To expand on ASD research of response inhibition of social stimuli by including additional negative facial emotions.
Methods:
37 children from two groups (25 ASD; 12 TYP) matched on age (7-12 years), IQ (70+), gender ratio, and socioeconomic status completed an E-prime emotional Go/NoGo response inhibition task. The task consisted of two block types (Go and NoGo trials) across three facial emotions (fear, sadness, and happiness). Neutral faces were paired with the Go or NoGo emotional stimuli within each block type.
Results:
False alarm (FA) rates and mean response time (RT) did not differ significantly across emotion condition or diagnostic group. However, the ASD group had a significantly greater mean standard deviation of RT during NoGo trials, F(1,35)= 4.82, p< 0.05. Due to this extreme variability, an Intra-individual Coefficient of Variation (ICV) was calculated for each participant. There were significant ICV group differences in NoGo trials, F(1,35)= 4.28, p< 0.05, and in fear trials, F(1,35)= 4.12, p= 0.05, demonstrating significantly greater variability in the ASD group during fear NoGo trials.
Conclusions:
Processing emotional stimuli does not significantly influence response inhibition accuracy or central tendency (i.e., mean RT) in children with ASD or TYP. However, children with ASD demonstrate significantly greater variability, as captured by the ICV, in their ability to inhibit responses to fearful faces. This finding has methodological implications, as it provides a quantifiable index of the phenotypic heterogeneity that is often discussed qualitatively in ASD research. It also demonstrates variability in an attentional bias to fearful stimuli in ASD.