When an owner shows affection to a fake dog, is their dog's reaction jealousy?

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These experiments adapted procedures used to study jealousy in human infants. The central question was whether dogs would act to protect their relationship with their owner when attention shifted to a potential rival.

In the primary experiment, dogs showed significantly more behaviors such as snapping, getting between the owner and the object, and pushing or touching the owner or object when the owner showed affection to what appeared to be another dog, compared with nonsocial objects. The researchers interpreted this as support for a basic form of jealousy, rather than proof that dogs experience the emotion as humans do.

The supplementary research reported two separate studies. In each, 36 adult dogs were ignored while their owner and a stranger directed positive attention to a book, a puppet or a fake dog. One study used a furry fake dog; the other used a plastic one. Dogs showed interest in the fake dogs, but a behavioral difference between the fake dog and the puppet appeared only in the plastic-dog study. Behaviors such as protesting, seeking attention or interfering were absent or limited. Responses to the owner and stranger did not significantly differ either.

Those studies found no clear sign that the dogs treated the fake dogs as genuine social rivals. This leaves the jealousy interpretation unsettled: the negative findings do not rule out jealousy in dogs, but these setups did not consistently demonstrate it. The supplementary researchers proposed testing real dogs or people as potential rivals in more natural situations.