Dr. Beecher's research examines bird song as a model communication system. Bird song is of considerable general scientific interest because it has proved to be the single best model system, involving a naturally-occurring complex behavior, for the study of learning and for the study of brain-behavior relationships. In addition, there are many surprising parallels between bird song and human language, including developmental and neurological similarities. Dr. Beecher's approach is unique in considering the song communication system from a perceptual point of view. Previous research has focussed on the signals, and has generally ignored the transformations performed on these signals by the animal's sensory-perceptual system. Methods have been developed in recent years that allow researchers to characterize the perceptual dimensions of a set of stimuli for an animal by training it to indicate the perceived similarity between a pair of stimuli for all possible pairs in the set. Dr. Beecher will use these and related methods to map the perceptual dimensions of the song system of the song sparrow, a species with a particularly complex and varied song. To examine the role of experience in the development of normal song, Dr. Beecher will compare birds raised with and birds raised without hearing normal species song. The latter birds sing abnormal song as adults, and Dr. Beecher expects to show that their song perception is abnormal as well. He will also examine song perception as it relates to the use of song in natural contexts, such as in the recognition of neighbors. He is particularly interested in song perception by females, since virtually nothing is known about song learning in females as they do not sing as adults. Dr. Beecher's general goal is to advance our understanding and increase the utility of this model system by providing information on the heretofore neglected perceptual side of song learning.