Answer:
A psychologist went to school to study the effects that situations have on the human brain and how the human brain copes or deals with those situations.
Step-by-step explanation:
Because they have the insight on would brings joy, stress, sadness, fear, etc. to the human mind or state, they can help video game designers better invoke those emotions through their games. They know what makes the human brain tick, so they can help scare, sadden, cheer up, or anger the audience the game developers are designing for. They know the difference between what will work or invoke different emotions to different audiences.