Some people may think of psychology as less of a science than physics or biology, because they might consider it subjective and don’t believe in personality types. But as any other science, psychology has a question, then a hypothesis and ways to confirm or deny it through experiments. It also can apply the results for problem solving.
You can even test out some of the things yourself. While there are a lot of myths about what works and doesn’t work, people on Reddit have already done the work themselves and witnessed the desirable results without anyone even knowing they were deliberately manipulating someone.