* : The asterisk (shift/8 on the keyword) is the truncation symbol used in most databases. It's a quick shorthand for singular, plural, noun and adjectival forms of words. For examples, addict* looks for: addict, addicts, addiction, addictions, addictive, etc.
Getting better search results using "AND" and "OR" - Rutgers University Libraries (2017)
Brief video (3 min. 20 sec.) features a combination of keywords for problem AND population AND treatment, plus tips on expanding terms and limiting search results.
University of East Anglia Library's video, "Using Index Terms on EBSCO PsychInfo," shows how to find specific subjects in PsycINFO.