Which subfield of psychology is concerned with how a person’s thoughts, feelings, and behaviors are influenced by interactions with others?

Psychology has many subfields depending on the concern that it tackles regarding a person's behavior and thinking. In this case, if it is focused on the person's feelings, thoughts, and behaviors that are affected by interactions with others, the subfield that covers this is SOCIAL PSYCHOLOGY. Hope this helps.

In 1947, after the vice presidency had been vacant for most of a presidential term, Congress again changed the line of succession. ... The amendment states that the president may appoint a vice president to fill a vacancy in that office, subject to approval by both houses of Congress.