The scientific interest in studying canine cognition has led to the development of a slew of test protocols—some uniquely designed for dogs and others modified from the field of comparative psychology. Many of them employ visual tasks to test dogs’ capabilities. In order to succeed with touch screens, at discriminating fine details in tests of their abilities to follow gazes or gestures, to understand object permanence, to identify faces or facial expressions, their visual perception is part of the equation. However, most of the studies are designed based on human, rather than canine, visual perception.
Canine vision differs from humans in a number of ways. Their ability to perceive a range of color hues is not as good as people’s ability, nor is their ability to distinguish levels of brightness or their visual acuity. Dogs are sensitive to higher flicker rates than people are, which can affect any studies that use moving items on computers or on televisions. There is evidence that dog vision is even more sensitive to movement than human vision.
Since visual perception abilities are not consistently accounted for in many studies with dogs, it is hard to know whether the test protocols are accurately assessing canine cognition. The results may be affected by visual capabilities instead. Researchers recently tested the hypothesis that visual perceptual differences between dogs and people could affect the performance in visually-based tasks using a free online tool (http://dog-vision.com) that converts images to settings that match what humans or dogs can see best. They report their results in the study “Do you see what I see? The difference between dog and human visual perception may affect the outcome of experiments”.
The test subjects in the study were humans, and they were asked to decide which side was indicated by a person in a series of photos. The photos showed a woman indicating a direction (right or left) by either pointing that way with her arm extended, by turning her head or by moving the gaze of her eyes in that direction without moving her head. People were tested with photos in their original form (set for human vision) and in a form altered for canine vision.
Participants in the study could correctly choose the direction of all three sorts of cues in the unaltered (human vision setting) photos. In the photos that were altered to the dog-vision setting, they could identify the cues in the pointing with extended arm and with the head turn quite well. However, their performance dropped considerably when asked the direction indicated by the gaze of the woman’s eyes in the dog-vision setting.
The results of this study suggest that differing visual capabilities may affect performance in visual tasks. The researchers acknowledge that this study only shows that human performance is influenced when visual tasks are designed for the other species, but it is likely that dogs are similarly affected. Though many experiments that do not account for vision differences between dogs and humans have still revealed intriguing canine capabilities, future research could benefit from doing so. It is likely that researchers could increase the number of unambiguous results and also eliminate the hassle of a large drop-out rate of subjects who do not meet preliminary criteria for inclusion in the study. Potentially challenging visual presentations are a problem in canine studies, and avoiding them will help scientists conduct better research.