The role of contour and intervals in the recognition of melody parts: Evidence from cerebral asymmetries in musicians

Abstract

The left hemisphere (LH) has been shown to be involved in tasks requiring interval-based procedures, and the right hemisphere (RH) in task allowing a contour-based approach in melody recognition. Support for this distinction was obtained by studying contour properties at the level of whole melodies and interval characteristics at the level of individual tones. The purpose of the present study was to extend the validity of this two-component model at the level of melody parts. It was predicted that both the LH interval-based procedure and the RH contour-based approach contribute to melody part recognition, but that their respective efficiency will depend on the structure of the parts used as recognition probes. To address this question along the lines of prior work [3] ( Bever and Chiarello, Science 185, 537–539, 1974), a probe recognition task was presented monaurally to right- handed musicians. The recognition probes that corresponded to one of the melody parts were found to be far more accurately and quickly recognized than the probes that bridged across the contour- defined boundary. On the latter, subjects performed initially at about chance level. They improved, however, after some exposure to the task, that is on the second half of the test material in Experiment 1 and on the second half of Experiment 2, and displayed the predicted interaction between laterality and probe type. Subjects recognized the probes that coincided with a part delineated by contour boundaries in the left ear (or the RH) more easily; whereas they recognized more easily the probes which crossed contour boundaries in the right ear (or the LH). These findings justify the consideration of contour as an important grouping factor in pitch sequences and emphasize the usefulness of laterality effects.