The impact of eyes on attributions of agency and experience in humanoid robots

Humans' tendency to attribute mental states to robots positively correlates with the increasingly human-like appearance of the robots. As eyes have been suggested to be "the windows to the soul", in the present study we investigated whether the presence or absence of facial features appearing as eyes in humanoid robots affects how perceivers attribute mental capacities of agency and experience to robots. We created images of highly realistic humanoid robots with full bodies and showed these robots either with the eyes or without the eyes. In Experiment 1, attribution of agency and experience was measured with self-evaluation questionnaires, whereas in Experiment 2, we used the Implicit Association Test (IAT). Results from both explicit and implicit measurements showed that humans attribute higher levels of agency and experience to humanoid robots with eyes (i.e. eyelike facial features) compared to robots without eyes. The results have great practical relevance to humanoid robot technology as the presence or absence of eyes in humanoid robots could have a fundamental effect on human-robot interaction.