A two-alternative choice test was used to behaviourally test the visual acuity in dogs and humans. In total three dogs were tested in daylight conditions, while two dogs were tested in dim light conditions. Eight humans were tested in both daylight and dim light conditions. 

The dogs were trained to choose one of two presented visual stimuli, either a stimulus with vertical or horizontal black and white gratings. The humans were told before the test which grating orientation to chose. 

To be able to determine the acuity threshold the stimuli used varied in spatial frequency.  The threshold for visual acuity was measured in cycles per degree (CPD) and was determined using a binomial test. 

The video shows a test session with one of the dogs in the experimental set-up.