This is Scientific American's 60-second Science, I'm Susanne Bard."I thought you were downstair boxing chocolates.""Oh, they kicked me out of there. I kept pinching them to see what kind they were."Laugh tracks in television shows like I Love Lucy have been encouraging us to chuckle since the 1950s.But they originated even before that with old radio shows."If you just put out a comedy program on the radio, people didn't necessarily realize it was supposed to be funny.So they started recording them with a live audiencebecause then people had all the cues that they would get if they were at the theaters, say―of an audience response.And, indeed, laughter can be highly contagious."Sophie Scott is a cognitive neuroscientist at University College London.She and her team wondered whether adding laughter to a joke could also make it seem funnier.So they scoured the Internet for the most groan-worthy jokes they could findand enlisted the help of a professional comedian to record them."So things like 'What's the best day for cooking? Friday.How does a dinosaur pay its bills? Using tyrannosaurus checks,' that kind of thing.And then we got people to rate how funny they were without any laughter added."The researchers paired the jokes with both spontaneous, involuntary laughter and with laughter that had been produced on demand."What do you get when you ask a lemon for help? (Lemon aid)"They played these recordings to adults, some neurotypical and some on the spectrum.