Empathy-related responses to moving film stimuli depicting human and non-human animal targets in negative circumstances.

Research supports an "ingroup empathy hypothesis" of higher empathy-related psychophysiological responses towards individuals of the same ethnicity. However, little research has investigated empathy-related responses to non-human targets graded for phylogenetic relatedness. Participants (N=73) were presented with film stimuli depicting humans, primates, quadruped mammals and birds in victimized circumstances. Phasic skin conductance responses (SCR) and subjective empathy-related ratings to the film clips increased as phylogenetic similarity to humans increased across animal groups, revealing an empathic bias towards human stimuli. Participants also completed a trait empathy scale. High trait empathy participants gave higher subjective empathy ratings than moderate and low trait empathy participants. Low trait empathy participants showed less corrugator electromyographic activity than moderate and high empathy participants. The moderate trait empathy participants showed higher SCR than the high group. The results confirm an effect of phylogenetic similarity in subjective self-report and psychophysiological measures of empathy-related responses. Additionally, convergence between subjective and objective measures of empathy-related responses was observed.