Dogs’ looking times and pupil dilation response reveal expectations about contact causality

Contact causality is one of the fundamental principles allowing us to make
sense of our physical environment. From an early age, humans perceive
spatiotemporally contiguous launching events as causal. Surprisingly
little is known about causal perception in nonhuman animals, particularly
outside the primate order. Violation-of-expectation paradigms in
combination with eye-tracking and pupillometry have been used to study
physical expectations in human infants. In the current study, we establish
this approach for dogs (Canis familiaris). We presented dogs with
realistic 3D animations of launching events with contact (regular
launching event) or without contact between the involved objects. In both
conditions, the objects moved with the same timing and kinematic
properties. The dogs tracked the object movements closely throughout the
study but their pupils were larger in the No-contact condition and they
looked longer at the object initiating the launch after the No-contact
event compared to the Contact event. We conclude that dogs have implicit
expectations about contact causality.