Last night, on her 26th appearance - Julia Roberts, one of Dave's best guests, recalls being reluctant to show up to her very first interview with David Letterman.
Famous for many things, among these her infectious smile and laughter - the accomplished actress here displays a rarely discussed and fantastic nonverbal quality of sincere laughter. In this image and its close-up captured below (during 5:59), we can see both Dave and Julia in the midst of sincere laughter. Roberts, seen in-profile, is retracting (pulling in) her jaw (Letterman is too - however the camera angle doesn't afford us the same view). Although there are certainly times when laughter is sincere and this particular body language of jaw retraction is not seen (e.g., not all sincere laughter is the same), whenever jaw-retraction is displayed - you can be sure the laughter is indeed sincere.
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