Physiognomy was the belief that the study of a person's external appearance, esp. the face, was reflective of their character or personality.
Captain Picard attended what was supposed to be a physiognomy workshop at a three-day psychological conference discussing the effects of deep space assignments in late 2369. The presenter, Doctor Vassbinder, was not aware of the intended subject and instead gave a hypnotic hour-long dissertation on the ionization effect on warp nacelles. (TNG: "Timescape")