As suspected, this paper is based upon Paul Ekman's Facial Action Coding System, better known as micro-expressions.
This controversial literature borderlines on pseudo-science, with Ekman's work having significant conflicts of interest in the form of undisclosed funding from US defence, police, and border control, who wanted Ekman to create systems that can detect lies based on supposed micro expressions. Subsequent independent meta analyses have found that micro expressions cannot be consistently read, even by Ekman's own researchers.
Unfortunately, despite this, world governments have poured millions of dollars into private contractors to develop AI systems based on this flawed research for border control.
Munecat's video essay on debunking body language experts goes into much greater detail: