title: Toward an operational definition of anhedonia.
mesh_terms: D000293:Adolescent; D000328:Adult; D006240:Happiness; D006801:Humans; D007845:Laughter; D008149:Love; D008950:MMPI; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia