Augustin Lignier, a photographer in Paris, created a photo booth for rats. He took inspiration from B.F. Skinner, the famous researcher who made The Skinner Box, designed to dispense food pellets when rats pushed a designated lever.

It became one of the most well-known experiments in psychology. 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. But then 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 very powerful, keeping animals glued to their slot machines as they await their next jackpot.

In the face of these unpredictable rewards, the rats ignored the sugar even when it did arrive, 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.