19.07.2023: Like human children, dogs have expectations about their environment, for example about whether and when an object moving behind a cover should be visible. If these expectations are violated, they become curious and explore their surroundings more closely. A research team from the University of Veterinary Medicine Vienna was able to demonstrate these parallels between humans and dogs in a new study.

Previous studies have shown that human infants react with curiosity when basic physical regularities are violated. Such unusual events stimulate them to examine the objects involved more closely, which might give them insights into new causal relationships.

In their study, the scientists investigated whether a similar relationship between violations of expectations and exploration exists in non-human animals. Specifically, they investigated how dogs respond to expectancy violations associated with temporarily hidden objects - so-called occlusion events.

In the first two experiments, the dogs saw videos of a ball moving across the screen. The ball moved behind covers of different widths as the videos progressed. In the first experiment, the ball rolled past behind a narrow cover and either appeared on the other side, as would be expected under real conditions, or disappeared behind the cover. In the second experiment, a ball rolled past two covers with a gap between them. In one condition, the ball reappeared in the gap as would be expected under real conditions, whereas in the other condition it did not reappear in the gap. In the third experiment, the second experiment was repeated, but now not as a video, but with a real ball.

Violated expectations stimulate curiosity

"In all three experiments, dogs showed longer looking times for events that violated expectations than for consistent events. This result was further supported by pupil size analyses in the first two experiments. Our results suggest that dogs expect objects to reappear when they are not occluded by an opaque screen and that they consider the size of the screen in relation to the occluded object," says first author Christoph Völter from the Messerli Research Institute at Vetmeduni.

In the third experiment, violations of expectation increased the dogs' motivation to investigate the target object more closely - similar to what has been found with human infants. "The surprise reaction of the dogs led to increased exploration of the object involved, which opened up the possibility for them to find out more about the unusual properties of the object. Overall, we conclude that expectancy violations might also provide learning opportunities for non-human animals," says Völter.