Marco Leyton, PhD, assures me the cocaine he purchased was legal. Plus, it wasn’t for him. Definitely not. It was for recreational cocaine users who had answered Leyton’s ad in a local newspaper to do drugs and collect 500 Canadian dollars — for science.

Leyton had jumped through many hoops to get to this point — getting an okay from the Canadian equivalent of the FDA, exempting him from criminal prosecution, and clearing his own university’s ethics approval. “I wasn’t asking people to bring in their own cocaine,” Leyton, an addiction neurobiologist at McGill University in Canada, tells me. Now that could be unethical.

It was all in pursuit of one of the deepest questions that haunts us as individuals: “Why do we really care about some things and not too much about others?” as Leyton says.

Really: Why do we want what we want?

. . .

After talking to several researchers for this story, I realized the English word “want” is imprecise to describe the psychological phenomenon Leyton has been describing.

“It’s not your desire for world peace,” says Kent Berridge, a neuroscientist at the University of Michigan. “It’s not my desire to exercise or lose weight.” Those are “real desires,” he assures. But they are not behind the sort of behavior that is facilitated by the dopamine system in the brain. “They don’t give you that kind of urge.”

. . .

It’s a manifestation of our mesolimbic system, the reward pathway in the brain that’s facilitated by dopamine. It’s a system that’s trained, over time, to influence our decisions. It’s the system that compels you [. . .] toward [. . .] things, like scrolling through endless TikToks or Instagram reels.

Read the complete article in Vox