Research shows that information received by one brain hemisphere (e.g., auditory messages entering the right ear) is processed and transferred to the other, interpretation being a combination of right and left brain processing, with high intensity messages shifting control from the left to the right brain. If information is received by one hemisphere in isolation from the other (e.g., monaural reception inhibited by cross-ear masking), the opposite hemisphere must rely on input from the first hemisphere as if it were the same information it would normally receive from the ear. Hence, the analyses may be skewed by the different semantic and syntactic style of each hemisphere. In P. MacLean's concept of a hierarchical "triune brain"--three evolutionary brains stacked vertically--auditory messages are normally first processed by the R-Complex brain, reinterpreted by the Paleomammalian brain, and finally integrated and processed according to social rules and the logic of human experience in the Neomammalian brain. Together these theories imply that the auditory processing of advertisements is mediated by hemispheric style and possibly influenced by the evolutionary level of the brain controlling message interpretation. Thus, the type of advertising message (propositional versus nonpropositional, high versus low intensity) combined with masking (e.g., sales pitches using background noise heard on "walkman" radios) could obtain different degrees of acceptance by inducing isolated hemisphere reception. (JG)