We’ve all heard it before: smoke weed, and you’ll become a lazy, unmotivated bum. The image is vivid – a glassy-eyed stoner sprawled on a couch, surrounded by pizza boxes, with a suspicious crust on their sweatpants that may or may not be dried Ranch dressing. This stereotype has been hammered into our collective consciousness for decades, from “Reefer Madness” to those infamous “This is your brain on drugs” PSAs.