Similar impressions of humanness for human and artificial singing voices in autism spectrum disorders.

People with autism spectrum disorder (ASD) exhibit impairments in the perception of and orientation to social information related to humans, and some people with ASD show higher preference toward human-like robots than other humans. We speculated that this behavioural bias in people with ASD is caused by a weakness in their perception of humanness. To address this issue, we investigated whether people with ASD detect a subtle difference between the same song sung by human and artificial voices even when the lyrics, melody and rhythm are identical. People without ASD answered that the songs sung by a human voice evoked more impressions of humanness (human-likeness, animateness, naturalness, emotion) and more positive feelings (warmth, familiarity, comfort) than those sung by an artificial voice. In contrast, people with ASD had similar impressions of humanness and positive feelings for the songs sung by the human and artificial voices. The evaluations of musical characteristics (complexity, regularity, brightness) did not differ between people with and without ASD. These results suggest that people with ASD are weak in their ability to perceive psychological attributes of humanness.