Theory is the branch of psychology that studies the perception of reality and the mental processes required to understand the world we live in?

Cognitive theory

Explanation:

Cognitive theory of cognitive psychology is the psychology that studies the internal mental process of human beings as well as animals. It includes perception, cognition, thinking, memory, learning, attention, concentration, and language, etc. It is the latest branch of psychology.

This is the helping psychology branch that helps in many disorders and in making a decision problem. To help people from recovery in head brain injury.

Thus here in the above context, it talks about the cognitive psychology that deals in cognition or mental process of people.