"Dominance of the left hemisphere for such analytic functions would explain dominance of the right ear for melody recognition in experienced listeners: as their capacity for musical analysis increases, the left hemisphere becomes increasingly involved in the processing of music. This raises the possibility that being musically sophisticated has real neurologic concomitants, permitting the utilization of a different strategy of musical apprehension that calls on left hemisphere functions."1
The study of music and the brain has received recent attention in part through the publication of Daniel Levitin’s This Is Your Brain on Music2 and Oliver Sacks, Musicophilia.3 The next article in the Classic Series honors the seminal work of Thomas G. Bever and Robert J. Chiarello conducted at Columbia University. The experiment addressed an apparent paradox. A prevailing theory, first proposed by Hughlings Jackson,4 was that cognitive activity in the left hemisphere was specialized for propositional and serial analytic processes whereas the right hemisphere was involved in holistic associational processing. This suggested that the apparent dominance of the left hemisphere for language and mathematics and the apparent dominance for the right hemisphere for handling art and music reflected a difference in computational processing. The view that music would be preferentially managed by the right hemisphere was bolstered by multiple studies demonstrating left ear superiority for the recognition of musical melodies. These studies were also based on the premise that monaural presentation of stimuli, though processed by both hemispheres, is associated with dominance of the contralateral hemisphere.5 Bever and Chiarello were predominantly interested in using music as a window for testing assumptions about functional cerebral asymmetry. The apparent preference for left ear listening for music, and by inference, right hemisphere processing, was difficult to explain because music is organized in serial patterns of notes and phrases which presumably would favor a preference for left hemisphere processing.
Bever and Chiarello’s innovation was to compare experienced musicians to nonmusicians on ear preference and their ability to accurately identify a two-note excerpt versus the full melody. The latter task was chosen to test their ability to analyze music by its subcomponents. Nonmusicians showed a preference for the left ear to identify whole melodies consistent with prior studies suggesting right hemisphere preference for processing musical information. Further, the nonmusicians were not able to accurately identify two-note excerpts. In contrast experienced musicians showed a right ear preference and were able to identify subcomponents. The results suggested that musical training recruited left hemisphere processing. These results show that music can be appreciated holistically as well as analyzed by its structure of subcomponents. It also shows that musical training can result in a remodeling of stimulus processing. This fits both the idea of neurologic plasticity and that musical training can actually change the physical structure of the brain.
In a phone interview, Dr. Bever stated that the experiment grew out of an honors thesis by Robert Chiarello, who was a senior at Columbia University. The citation record shows a bimodal pattern with a large number of citations in the years following the initial publication and a resurgence of citations in recent years. Dr. Bever speculated that this may relate to a rekindling of the debate on the fundamental basis of cerebral asymmetry; that is, are the hemispheres differentiated to manage different stimulus response modalities, or differentiated by aspects of computational efficiency? The results from many functional imaging studies have contributed to a reemergence of the modular view of cognitive processes, thus the debates lives on. The Bever and Chiarello article is an excellent example of how an elegant and efficient experiment can have an enduring impact on a major question in the brain sciences. And yes, both authors were enthusiastically interested in music in addition to the broad issues related to cerebral asymmetry.