Are humanoid robots perceived as mindless mannequins?

The shape and texture of humans and humanoid robots provide perceptual information that help us to appropriately categorise these stimuli. However, it remains unclear which features and attributes are driving the assignment into human and non-human categories. To explore this issue, we ran a series of five preregistered experiments wherein we presented stimuli that varied in their appearance (i.e., humans, humanoid robots, non-human primates, mannequins, hammers, musical instruments) and asked participants to complete a match-to-category task (Experiments 1-2-3), a priming task (Experiment 4), or to rate each category along four dimensions (i.e., similarity, liveliness, body association, action association; Experiment 5). Results indicate that categorising human bodies and humanoid robots requires the integration of both the analyses of their physical shape and visual texture (i.e., to identify a humanoid robot we cannot only rely on its visual shape). Further, our behavioural findings suggest that human bodies may be represented as a special living category separate from non-human animal entities (i.e., primates). Moreover, results also suggest that categorising humans and humanoid robots may rely on a network of information typically associated to human being and inanimate objects respectively (e.g., humans can play musical instruments and have a mind while robots do not play musical instruments and do have not a human mind). Overall, the paradigms introduced here offer new avenues through which to study the perception of human and artificial agents, and how experiences with humanoid robots may change the perception of humanness along a robot—human continuum.