Method A: Look for Subject (thesaurus) terms at the right of a search results page OR at the bottom of a citation.
Method B: Go Directly to the Thesaurus: From the Advanced Search screen in PsycInfo, you can search the Thesaurus (link found above search box). See screenshots below.
Explode option (expands) - retrieves all sources tagged with the subject PLUS sources tagged with narrower subject terms.
Major option (targets) - retrieves sources with the subject heading as the major point of the article.