In a study of the relationship between extraversion and the amygdala that is described in the textbook, participants viewed fearful or happy faces while they underwent fMRI scans. Researchers found that the faces elicited relatively high levels of activity in the amygdala of highly extraverted people.

happy faces, left

Explanation:

Our emotions what we feel are controlled by the limbic system. One of the parts of the limbic system called the amygdala is involved in the processing of emotions, motivation, and memories. Researchers have found that the happy faces show high levels of the activity of the left amygdala as the amygdala also controls the facial expressions caused due to emotions.

how do you know that

explanation:

answer; i believe its called ; checks   and balances;