The ability to improvise represents one of the highest levels of musical achievement. An improviser must master a musical language to such a degree as to be able to spontaneously invent stylistically idiomatic compositions on the spot. This feat is one of the pinnacles of human creativity, and yet its cognitive basis is poorly understood. In this dissertation, I explore cognition in improvisation, seeking to answer the following three questions: What is the knowledge base necessary for improvisation? How is this knowledge acquired? How is this knowledge used in performance?

To pursue answers to these questions from a variety of vantage points, I draw on several sources, methodologies, and disciplines. An examination of pedagogical treatises on improvisation from the mid-eighteenth and early nineteenth centuries yields insights into how improvisation in that style was taught. Interviews with Robert Levin and Malcolm Bilson, both present-day improvisers in this same style, allow for an exploration of how improvisation is learned, as well as providing performers' perspectives on the experience of improvising. Transcriptions and analyses of Levin's and Bilson's improvisations yield further insights into the processes described in those interviews. I discuss the findings from these sources in cross-cultural context, comparing them with improvisation practices in a variety of traditions. Complementing these musicological and ethnomusicological materials and techniques, I discuss improvisation from a neurobiological perspective, drawing on brain imaging research that I conducted in collaboration with Daniel Ansari.

Though disparate, these sources provide a convergent picture of the improvising mind, suggesting that musical improvisation draws on some of the very same cognitive processes and neural resources as the more mundane but equally infinitely creative faculties of spontaneous speech and action. I therefore examine the comparison of music and language cognition with respect to both learning and performance, expanding on previous research in the area of music-language comparisons that has focused largely on perception and the sound systems themselves. By combining the techniques and disciplines of historical musicology, ethnomusicology, and cognitive neuroscience, I seek to explore cognition in improvisation from diverse perspectives, and to situate my findings in a broad cultural and scientific context.