When Augustin Lignier, a professional photographer in Paris, was in graduate school, he began to ponder the point of picture-taking in the modern world: Why did so many of us feel compelled to photograph our lives and share those images online?

It was not a novel question, but it led Mr. Lignier to a surprising place, and before long he found himself building what was, in essence, a photo booth for rats.

He took inspiration from B.F. Skinner, the famous behaviorist who had devised a test chamber to study learning in rats. The Skinner box, as it became known, dispensed food pellets when rats pushed a designated lever.

It became one of the most well-known experimental paradigms in psychology. Scientists found that reward-seeking rats became lever-pressing pros, pushing the bar down over and over again in exchange for food, drugs or even a gentle electric zap directly to the pleasure center of the brain.

Mr. Lignier built his own version of a Skinner box — a tall, transparent tower with an attached camera — and released two pet-store rats inside. Whenever the rats pressed the button inside the box, they got a small dose of sugar and the camera snapped their photo. The resulting images were immediately displayed on a screen, where the rats could see them. (“But honestly I don’t think they understood it,” Mr. Lignier said.)

The rodents quickly became enthusiastic button pushers. “They are very clever,” Mr. Lignier said. (He named the white rat, which proved to be the cleverer of the two, Augustin, after himself. The brown and white rat he named Arthur, after his brother.)

But after this training phase, the rewards became more unpredictable. Although the rats were still photographed every time they hit the button, the sweet treats came only once in a while, by design. These kinds of intermittent rewards can be especially powerful, scientists have found, keeping animals glued to their experimental slot machines as they await their next jackpot.

Indeed, in the face of these unpredictable rewards, Augustin and Arthur — the rats — persisted. Sometimes, they ignored the sugar even when it did arrive, Mr. Lignier said, and just kept pressing the button anyway.

To Mr. Lignier, the parallel is obvious. “Digital and social media companies use the same concept to keep the attention of the viewer as long as possible,” he said.

Indeed, social media has been described as “a Skinner Box for the modern human,” doling out periodic, unpredictable rewards — a like, a follow, a promising romantic match — that keep us glued to our phones.

Or maybe being able to keep ourselves busy pressing buttons is its own reward. In a 2014 study, scientists concluded that many human volunteers “preferred to administer electric shocks to themselves instead of being left alone with their thoughts.” Maybe we would rather sit around and push whatever levers are in front of us — even those that might make us feel bad — than sit with ourselves in quiet contemplation.

But that’s precisely the sort of thing that might be too uncomfortable to sit around and contemplate. Especially when there are rat selfies to marvel over — “I found them cute and fun,” Mr. Lignier said — and an endless stream of Instagram photos to scroll through or even, occasionally, enjoy.

Produced by Antonio de Luca and Matt McCann