facial leakage
n.— «Natural emotions are instantaneous, which makes them difficult to fake. When Auntie pops round at Christmas to give you your 18th pair of socks, you look pleased and surprised because anything else would be rude. But if you filmed it, you’d see something called facial leakage—the milliseconds where you’re searching for the right look.» —“Far too close for comfort” by Charlotte Phillips Times (London, United Kingdom) Aug. 11, 2007. (source: Double-Tongued Dictionary)