Use scientific methodology to study behavior and mental processes in order to understand why people behave, think and feel the way they do in a variety of situations.

Each type of situation (i. e. how someone behaves going to a party where they don't know anyone) should be tested individually. You should first observe people in the setting in question. Based on those observations, ask a question you want an answer to about what they may be feeling or thinking in that setting. Guess what you believe the answer to the question would be. You can gather data by asking those people what they were thinking and feeling. If there is a common emotion or theme to the answers, then you can determine if your initial hypothesis was correct.

I believe the answer is: Psychologist

Psychology is a discipline that aimed to study all aspects of mind and behavior (both conscious and unconscious)

Scientific methodology under this discipline is used to found out the pattern on how the majority people react/behave when they're placed under certain occurrences