Inter-human and animal-directed empathy: A test for evolutionary biases in empathetic responding

• Empathy towards non-human animals was examined using psychophysiological measures and subjective empathy and arousal ratings.
• Two theories of empathy were examined, namely a similarity effect and the nurturance explanation.
• Stronger phasic skin conductance responses and subjective ratings were found for phylogenetically similar species.
• Although HR was lower during infant stimuli presentations, the magnitude of change resembled that reported for neutral stimuli.
• Subjective empathy and arousal ratings were higher for human infants but this did not extend to non-human infants.

Empathy is facilitated by the perceived similarity between the object and subject. Conversely, nurturance has been suggested to influence empathy, in that humans have an ability to empathise with non-kin in a similar way as with their own offspring when certain characteristics (e.g., childlikeness) are present. To examine the combined effects of similarity and nurturance, participants (n = 69) were presented with images of infant and adult human and wild non-human animals (non-human primates, quadruped wild mammals, and wild birds) depicted in negative, victimising situations. Stronger phasic skin conductance responses and subjective ratings of empathy and arousal were observed for phylogenetically similar species. Subjective empathy and arousal ratings were greater for human infants but this did not extend to the non-human infants. Heart rate was lower during infant than adult stimuli presentations, however, the magnitude of change resembled that previously reported for neutral stimuli presentations. Although a similarity effect is widely acknowledged in the literature, the present findings point to the importance of taking into account both the age and the level of similarity with the target to gain a fuller understanding of empathy towards others of our own and different species.