Drug expectations associated with perceptual characteristics: ethnic factors.

For drugs, perceptual characteristics of size, form, and color have been associated with specific expectancies. Generally, capsules are perceived as stronger than tablets, larger capsules are seen as stronger than smaller ones, and some capsule colors have specifically ascribed expectations of drug action. This study replicated previous work with black subjects to assess perceptual constancies in drug expectancy between ethnic groups. 50 black subjects classified 12 colored capsules into 5 categories of drug action, rank-ordered 6 capsule sizes for relative strength, and compared a tablet and capsule for strength. Appreciable differences between white and black samples were noted for size-strength relationships and drug action expectancy associated with capsule colors. Results suggest ethnic implications for drug efficacy and compliance, with blacks less influenced by perceptual characteristics of drugs.