Stimulus generalization studies were conducted using rats trained to discriminate 1.0 mg/kg of the phenalkylamine hallucinogen 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM) from saline in a two-lever operant procedure. The results suggest that certain indolealkylamine hallucinogens, including LSD and several alpha-methyltryptamine, N,N-dialkyltryptamine and beta-carboline derivatives,...