Lightman and Foster tell the students possible but not necessary interpretations of the behavior they show to them. When Nixon looks down and hesitates it could be generated by an attempt to lie, but it could just as well be the product of being cautious in choosing his words, or as one of the students suggests, that he was checking his notes before giving a reply. An innocent person who knows he is under suspicion would be wise to be cautious about what he says, careful to check his notes. That is why we would call this a hot spot not a lie, it suggests something more is happening than what is being revealed, but only further questioning might reveal whether it is caution or a lie.
Foster says that crossed arms are defensive. Could be, but it could also be because the person is cold, feeling insecure, or stretching. Another hotspot. When a student challenges her Foster says that one such hotspot is not sufficient but many show lying; probably, but not necessarily. It would certainly take more than the two shown here to convince me.
Before Lightman begins his demo that he can spot whether the student Martin is lying, Martin quotes Telling Lies that without stakes there is no fear of being caught, hence no leakage that would betray a lie. Lightman then puts $100 down, which Martin will get if Lightman fails. That is better than no reward or a trivial reward (which has been typical in most research on deception), but our research found that it is not enough. The important stake is punishment, severe or humiliating punishment if caught. That is more likely to produce the overload on feeling and thinking that generates many hotspots.
Loker says that Andre was feeling regret when he looked down and away. Maybe, but that is not an evidence-based interpretation. There is a family of related feelings -– disappointment, discouragement, regret, guilt, shame, sadness -– that may be signaled by this expression. To my knowledge the research to link it to just one member of the family has yet to be done.