Dogs (Canis lupus familiaris) are susceptible to the Kanizsa's triangle illusion

Visual continuum in non-human animals: serial dependence revealed in dogs

Serial dependence is a recently described phenomenon by which the perceptual evaluation of a stimulus is biased by a previously attended one. By integrating stimuli over time, serial dependence is believed to ensure a stable conscious experience. Despite increasing studies in humans, it is unknown if the process occurs also in other species. Here, we assessed whether serial dependence occurs in dogs. To this aim, dogs were trained on a quantity discrimination task before being presented with a discrimination where one of the discriminanda was preceded by a task-irrelevant stimulus. If dogs are susceptible to serial dependence, the task-irrelevant stimulus was hypothesized to influence the perception of the subsequently presented quantity. Our results revealed that dogs perceived the currently presented quantity to be closer to the one presented briefly before, in accordance with serial dependence. The direction and strength of the effect were comparable to those observed in humans. Data regarding dogs' attention during the task suggest that dogs used two different quantity estimation mechanisms, an indication of a higher cognitive mechanism involved in the process. The present results are the first empirical evidence that serial dependence extends beyond humans, suggesting that the mechanism is shared by phylogenetically distant mammals.

Yes, dogs are susceptible to the Kanizsa's triangle illusion: A reply to Pepperberg

A recent paper by Pepperberg, Learning & Behavior, 51, 5-6, (2023) enquires about the validity of the finding that dogs are susceptible to the Kanizsa's triangle illusion, reported by Lõoke and coauthors (Lõoke et al., Animal Cognition, 25, 43-51, 2022). Here we elaborate on the matter, providing both theoretical considerations and further data, supporting the soundness of our previous conclusions.

Are dogs indeed susceptible to Kanizsa's triangle illusion?

Survival often depends on the ability of the visual system to process information accurately; thus, research demonstrating that a brain is susceptible to optical illusions is of considerable interest, particularly when the experiments involve phylogenetic comparisons. Are Lõoke et al.'s (Anim. Cogn, 25:43-51, 2022) data strong enough to allow the inclusion of dogs on the list of nonhumans that can perceive illusory Kanizsa figures?