Psychology
Defaults: IQ-6 or Sociology-4.
This is the skill of applied psychology, which may be learned by academic study or lengthy observation of human nature. Roll against skill to predict the general behavior of an individual or small group in a particular situation – especially a stressful situation. In settings with multiple sapient species, you must specialize by race. Defaults between specialties are up to the GM.
If the GM desires extra detail, he may rule that Psychology is split into two specialties: Applied (described above) and Experimental (for scientists who run rats in mazes and so forth). Applied defaults to Experimental-5; Experimental does not default to Applied, as a shrewd observer of people may lack training in scientific procedures.
Modifiers: +3 if you know the subject well; +3 if the subject is of a known deviant personality type; +1 for Sensitive or +3 for Empathy, or -3 for Low Empathy, if diagnosing a subject in your presence; -3 for Callous, unless specifically rolling to deduce someone's weaknesses so you can exploit them.