For Contagious Laughs, Open Your Mouth ... And get your vocal chords into it By Nick McMaster, Newser Staff Posted Nov 20, 2010 12:36 PM CST 4 comments Comments Even on sad occasions: Dina De Laurentiis is overcome with laughter with her mother Martha, rear, sister Carolyna, and others at the funeral of her father, filmmaker Dino De Laurentiis, on Nov. 15. (AP Photo/Reed Saxon, Pool) (Newser) – When it comes to laughs, the bigger the better, at least if you want it to spread. In one of those science-confirms-the-obvious studies, researchers found that open-mouth laughs in which people use their vocal chords in "vowel-like bursts" are the most contagious, LiveScience reports. And the longer they last, the more listeners like it (the laughter got ranked by college students). Breathy "courtesy" laughs or quiet chuckles got lower grades.