In Forty Studies That Changed Psychology by Roger R. Hock, Reading #21 from Chapter 6 from the textbook ("I can see it all over your face" by Paul Ekman and Wallace Friesen). What is the general area of psychology that the article dealt with ?

The study by Ekman and Friesen explored how the identification of emotion, through facial expressions, is similar between literate and preliterate groups. This argues for a certain universality of emotions, specifically, how facial expressions are interpreted cross-culturally.

As emotion is a prominent construct in the area of Personality Psychology and Social Psychology, I used this as my answer.

However, the design of this study also falls under Cross-Cultural Psychology.

Also note that emotion or facial expressions may also fall under other areas, such as Biological or Cognitive Psychology, depending on the specific research question of interest. In this case, the biological or cognitive aspects weren't as emphasized despite the facial recognition aspect.