An intense world? Heightened affective empathy for pain in ASD

Background: Empathy shapes our social behaviour, and is often thought to be reduced in autism spectrum disorder (ASD). However, reports of reduced empathy in ASD usually centre on cognitive empathy (i.e., thinking about others’ emotions) and largely neglect affective empathy (i.e., sharing or mimicking others’ emotions). Anecdotally, many adults with ASD report strongly experiencing emotion when viewing others' emotions or being overwhelmed by feelings when seeing someone in pain. However, previous empirical research on affective empathy has yielded conflicting results; with some evidence for heightened, intact and reduced affective empathy. Evidence from multiple convergent methods is necessary to better describe the affective empathy profile in ASD.

Objectives: We investigated affective empathy in individuals with varying levels of autism traits using three different paradigms: muscle mimicry, sympathetic nervous system response, and self-report.

Methods: We assessed 52 participants (ages 14 - 45) on the Autism Diagnostic Observation Schedule 2 (ADOS-2) and Autism Spectrum Quotient (AQ). Participants were classified, according to these measures, as having ASD (n = 15), having high ASD traits but no ASD diagnosis (n = 17), or having low ASD traits (n = 20). Participants were shown videos of painful stimuli (a needle stabbing a hand) and neutral stimuli (a static hand, a cotton bud touching a hand, or a needle stabbing a tomato). Muscle activity over the first dorsal interosseous (FDI; the muscle stabbed in the videos) and abductor digiti minimi (ADM; control muscle) was measured at 100ms intervals during the stimuli. Skin conductance was measured during the videos as an indicator of sympathetic arousal. Afterwards, participants rated the intensity of pain that they felt actors experienced. 

Results: Regression analysis of the EMG activity showed significantly higher FDI activation while viewing painful stimuli in the ASD group than in the low-ASD-traits group; F(2, 1807) = 5.65, p = .004. A mixed factorial ANOVA (condition x group) indicated that skin conductance was, on average, higher in the ASD and high-ASD-traits groups than in the low-ASD traits group, F(2,111) = 6.04, p = .005. The ASD and high-ASD-traits groups reported significantly higher perceived pain than the low-ASD-traits group; F(2,184) = 4.07, p = 0.019. 

Conclusions: Affective empathy for pain, as measured by muscle mimicry, skin conductance levels and self-report, is intact in ASD. Contrary to statements that individuals with ASD have reduced empathy, we found heightened reporting of others’ pain and heightened sympathetic arousal and mimicry in individuals with ASD and those with high ASD traits. Current evidence suggests that, rather than being insensible to others' pain, individuals with ASD experience it more intensely.