When children didn’t expect a reward, receiving one had little impact on their intrinsic motivation. Only contingent rewards—if you do this, then you’ll get that—had the negative effect. Why? “If-then” rewards require people to forfeit some of their autonomy. Like the gentlemen driving carriages for money instead of fun, they’re no longer fully controlling their lives. And that can spring a hole in the bottom of their motivational bucket, draining an activity of its enjoyment.
