this psycinfo guide provides useful information on the following:
remember to use boolean operators between keywords or phrases to control how they are treated in a database. this applies to most databases, not just psycinfo.
and
use and to narrow a search and retrieve records containing all of the words it separates, e.g. adolescents and children will only find records containing both these words.
or
use or to broaden a search and retrieve records containing any of the words it separates, e.g. adolescents or children will find records containing adolescents only, children only, or both words.
not
use not to narrow a search and retrieve records that do not contain the term following it, e.g. adolescents not children will find records that contain adolescents, but will not contain the word children.
subject headings are words or phrases assigned to articles in a database that describe its subject content. the terms assigned are selected from a standardized list of headings specific to the database.
subject headings allow you to search for all articles on a particular topic without having to brainstorm all the possible ways to describe that topic. using a subject term instead of a specific word/phrase allows you to broaden your search.
subject headings are also referred to as controlled vocabulary, index terms, thesaurus terms or something more specific:
psycinfo - subject terms
medline - mesh (medical subject headings)
embase - emtree terms
subject terms may differ across databases so if you are searching multiple databases, you will need to identify the available subject terms for each database and revise your search strategy accordingly.
the video below explains why the use of subject terms is not only useful but important.