When you look at a bulldog's face, your eyes are working harder than you know. Scientists at Braude College of Engineering in Karmiel, Israel, paired with researchers from Czechia and Hungary, have discovered something surprising: humans require significantly more cognitive effort to read the facial expressions of brachycephalic dogs—breeds like bulldogs, pugs, and Boston terriers with their characteristic flat faces and compressed airways—compared to dogs with more typical snouts.
The finding matters because brachycephalic breeds have exploded in popularity despite serious health concerns. French bulldogs alone have ranked as the most popular dog breed registered with the American Kennel Club every single year from 2022 to 2025, and bulldogs have consistently ranked in the top five since 2013. Yet as these breeds have become beloved companions, a crucial question has gone largely unexamined: can their owners actually read what their dogs are feeling?
To investigate, the research team recruited 44 undergraduate volunteers from their campus and asked them to examine photographs of Boston terriers and Jack Russell terriers in four different scenarios: being called by name, playing, separated from their owners, and being threatened by a stranger. While the volunteers studied these images, sophisticated eye-tracking technology measured exactly where they looked, how many times they shifted their gaze, and for how long they focused on different areas.
The results were striking. Volunteers made 42 percent more visual visits to images of the brachycephalic dogs and recorded 46 percent more saccades—those rapid, involuntary eye movements that dart between focal points—while studying them. They also spent 45 percent more total time gazing at brachycephalic dogs than normocephalic ones. Yet here's the puzzle: the average time they spent looking at any single spot was nearly identical between the two breeds, differing by only 1.3 percent.
What this tells us is that volunteers weren't simply taking longer to look; they were looking more restlessly, searching harder to find the information they needed. Their brains were working overtime, repeatedly scanning the flatter faces of brachycephalic dogs in a way they simply didn't need to do with more conventionally shaped faces. The researchers note that the compressed spatial arrangement of facial features in brachycephalic breeds—those pedomorphic, infant-like proportions that may trigger nurturing responses—simultaneously constrains the range of facial movements available for social signaling. In other words, the very features that make these dogs so appealing to humans may make them harder to read emotionally.
Interestingly, the volunteers' gender made no statistical difference in their ability to interpret dog faces, nor did their ownership status. Whether someone owned a normocephalic dog, a brachycephalic dog, or no dog at all didn't significantly affect how their eyes moved across the photographs.
The implications extend beyond eye movement studies. As brachycephalic breeds continue their rise in popularity, this research suggests that their owners may be working harder—often without realizing it—to understand what their dogs are feeling. That extra cognitive load could affect how well humans respond to signs of distress or discomfort in breeds already burdened by respiratory challenges and other health complications. Understanding this gap between what brachycephalic dogs express and what humans can read may be essential for improving the welfare of some of the world's most beloved dog breeds.