How knowledge of the song influences the matching of "melodies" to rhythm sequences tapped in the right and left palms.

Previous work by O'Boyle and Sanford (1988) has demonstrated that the right hemisphere (RH) is superior to the left hemisphere (LH) in the matching of tape-recorded melodies to rhythm sequences tapped in the palms of the hands. This asymmetrical advantage was attributed to a RH superiority in the perceptual processing of intonation as compared to the rhythm component of these musical stimuli. In the present study, subjects were taught that the monotone sound of two wooden drumsticks struck together in a specified rhythm actually represented non-melodic translations of songs with identifiable melodies. After such mental associations had been formed, these non-melodic stimuli (which produced no asymmetric performance in Exp. 2 of the O'Boyle and Sanford study), now produced a RH advantage that was comparable to that induced by the original melodies. This finding suggests that the physical presence of intonation and its subsequent perceptual analysis, are not necessarily critical to the RH advantage reported by O'Boyle and Sanford (1988). Rather, the asymmetry may be related to a superior ability of the RH to generate and/or manipulate echoic images in memory.