Automatic facial responses to affective stimuli in high-functioning adults with autism spectrum disorder

Individuals with autism spectrum disorder (ASD) demonstrate atypical behavioural responses to affective stimuli, although the underlying mechanisms remain unclear. Investigating automatic responses to these stimuli may help elucidate these mechanisms. 18 high-functioning adults with ASDs and 18 typically developing controls viewed 54 extreme pleasant (erotica), extreme unpleasant (mutilations), and non-social neutral images from the International Affective Picture System (IAPS). Two-thirds of images received an acoustic startle probe 3 s post-picture onset. Facial electromyography (EMG) activity (orbicularis, zygomaticus, corrugator), skin conductance (SCR) and cardiac responses were recorded. The adults with ASDs demonstrated typical affective startle modulation and automatic facial EMG responses but atypical autonomic (SCRs and cardiac) responses, suggesting a failure to orient to, or a deliberate effort to disconnect from, socially relevant stimuli (erotica, mutilations). These results have implications for neural systems known to underlie affective processes, including the orbitofrontal cortex and amygdala.

► Adults with Asperger's demonstrate typical affective startle modulation to erotica and mutilation.
► They also demonstrate typical automatic zygomaticus and corrugator EMG responses to these stimuli.
► They displayed dampening in SCRs and ECA to affective (pleasant/unpleasant) but not neutral images.
► Atypical autonomic responses suggest a failure to orient to socially relevant stimuli.