Self-propelled motion cues elicit the perception of inanimate objects as animate. Studies usually rely on the looking behaviour of subjects towards stimuli displayed on a screen, but utilizing artificial unidentified moving objects (UMOs) provides a more natural, interactive context. Here, we investigated whether cats and dogs discriminate between UMOs showing animate vs inanimate motion, and how they react to the UMOs' interactive behaviour. Subjects first observed, in turn, the motion of an animate and an inanimate UMO, and then they could move freely for 2 min while both UMOs were present (two-way choice phase). In the following specific motion phase, the animate UMO showed one of three interactive behaviours: pushing a ball, a luring motion, or moving towards the subject (between-subject design). Then, subjects could move freely for 2 min again while the UMO was motionless. At the end, subjects were free to move in the room while the UMO was moving semi-randomly in the room. We found that dogs approached and touched the UMO(s) sooner and more frequently than cats, regardless of the context. In the two-way choice phase, dogs looked at the animate UMO more often, and both species touched the animate UMO more frequently. However, whether the UMO showed playing, luring or assertive behaviour did not influence subjects' behaviour. In summary, both species displayed distinctive behaviour towards the animate UMO, but in dogs, in addition to the physical contact this was also reflected by the looking behaviour. Overall, dogs were more keen to explore and interact with the UMO than cats, which might be due to the general increased stress of cats in novel environments. The findings indicate the importance of measuring multiple behaviours when assessing responses to animacy. The live demonstration using artificial agents provides a unique opportunity to study social perception in nonhuman species.
Keywords: UMO; animacy perception; animal-robot interaction; cat; dog.
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