Social and Non-Social Threat Detection in Autism Spectrum Disorders

Background: Previous research demonstrates that individuals with Autism Spectrum Disorders (ASD) are inhibited in processing social cues, including social threat (Krysko & Rutherford, 2009). For example, while participants with ASD detect threatening faces more quickly and accurately than friendly faces, they demonstrate overall slower response times and increased error rates relative to typical controls (Krysko & Rutherford, 2009). Other research has shown that individuals with ASD do not display a disadvantage when detecting non-social threat-related stimuli (South et al., 2008). We are not aware of previous research that directly compares the within-subjects relationship for response to social threat versus non-social threat in ASD.

Objectives: We explored whether adolescents with ASD have difficulties detecting threat in general, or whether adolescents with ASD are only disadvantaged when interpreting threat relating to socially salient stimuli. We hypothesized that adolescents with ASD will demonstrate decreased reaction time and error rates relative to typically-developing adolescents when viewing social threat-related stimuli. We also hypothesized that, when viewing non- threat-related stimuli with no social context, children with ASD will display intact performance relative to typically developing children.

Methods: Participants included 25 adolescents (3 females) ages 15-18 and diagnosed with an ASD (ASD group); compared to 25 typically-developing controls (CON group, 4 females) matched on age (M = 17. 24 years) and IQ (mean =107).  We utilized a “dot probe” task using words with either positive or neutral valence and both social threat (“lonely,” “foolish,” and “hopeless”) and physical threat (“injury,” “hazard,” and “disease”) words. The task displayed a word from one of the four categories, for 600 milliseconds prior to a dot appearing on the top or bottom of the computer screen (Keogh, Dillon, Georgiou & Hunt, 2001). The participant was asked to respond as quickly and accurately as possible regarding the location of the dot, along with determining when the dot appeared on the screen.

Results: Accuracy for all categories was at ceiling (>97% for all conditions for both groups). Repeated measures ANOVA of response times for the combined groups showed no significant main effect for threat condition but did show a significant main effect for diagnostic group, with the ASD group significantly slower than controls. The group x threat condition interaction was statistically significant. Planned decompositions showed that, as hypothesized, the ASD group did show a significant main effect for threat condition [F(2,23)=3.1, p<.05, η²=.14], with the Social Threat condition showing slower response time than the other conditions. There was no such effect for the TYP group as response time to all conditions was quite similar.

Conclusions: As hypothesized, adolescents with ASD displayed decreased reaction time to the social threat condition relative to the control group. However, there was no significant difference between groups in reaction time to the non-social threat condition. These results suggest that impaired threat detection in individuals with ASD is specific to social threat conditions rather than an overall delayed response to threat.