Now, after training and scanning a dozen dogs, my one inescapable conclusion is this: dogs are people, too.

Because dogs can’t speak, scientists have relied on behavioral observations to infer what dogs are thinking. It is a tricky business. You can’t ask a dog why he does something. And you certainly can’t ask him how he feels. The prospect of ferreting out animal emotions scares many scientists. After all, animal research is big business. It has been easy to sidestep the difficult questions about animal sentience and emotions because they have been unanswerable.

Until now.

By looking directly at their brains and bypassing the constraints of behaviorism, M.R.I.’s can tell us about dogs’ internal states. M.R.I.’s are conducted in loud, confined spaces. People don’t like them, and you have to hold absolutely still during the procedure. Conventional veterinary practice says you have to anesthetize animals so they don’t move during a scan. But you can’t study brain function in an anesthetized animal. At least not anything interesting like perception or emotion.