"Psychologists study mental processes and human behavior by observing, interpreting, and recording how people and other animals relate to one another and the environment. To do this, psychologists often look for patterns that will help them understand and predict behavior using scientific methods, principles, or procedures to test their ideas. Through such research studies, psychologists have learned much that can help increase understanding between individuals, groups, organizations, institutions, nations, and cultures."
[Excerpt taken from the Occupational Outlook Handbook]
Tip: For more books in addition to the ones listed below, do a search in our library's catalogy for "psychology" and "handbook." You will find many books on specific areas of psychology that go into the details of what professionals in those areas do and research.