Introduction to the special issue on jazz improvisation.

How do we define expert improvisers? What is the nature of their internal dialogue and external interaction during performance? How do we evaluate interaction between musicians during performance? Are certain domain-general abilities related to improvisation achievement? And, can a computer program model the improvisational process? These are some of the questions explored in this special issue of Psychomusicology: Music, Mind & Brain (PMMB) based on selected papers from the Improvising Brain Symposium held at Georgia State University in Atlanta, Georgia, April 7-9, 2013. The opening event consisted of a concert performed by jazz musicians and related interview in which the featured jazz violinist and the accompanying rhythm section players were asked about their thinking as they listened to short excerpts played back from the just completed performance. In this introduction, I briefly describe interview data from this event as a way to introduce selected articles that make up the core of this special issue. A separate conference report by Steven Anderson describes some of the other papers presented at the symposium.The interview event was conceived as a way to explore interaction between jazz musicians during small group performance. Previous research has outlined the primary importance of this interaction (Berliner, 1994; Monson, 1996; Sawyer, 2006; Vuust & Roepstorff, 2008). Monson interviewed expert jazz musicians looking at a full transcription of a piano trio performance. They described how intimate knowledge of the style allowed them to signal to each other using various techniques including obscure musical references. However, the interview was conducted long after the actual performance took place.The current event was based on a methodology I used in previous research with individual jazz performers (Norgaard, 2011). During each session, I first asked the improviser to perform a blues improvisation along with a recorded drum loop. I then converted their performance to approximate notation that I displayed while playing the original audio in synchrony. This served as the basis for a directed interview in which the performer described his thinking. This design specifically eliminated any external cues, as the performances were recorded in a solo setting. Though the results included important descriptions of the thinking of artist-level improvisers, obviously information about interaction with other players and audience could not be collected.The Improvising Brain concert event offered an opportunity to investigate the thinking of artist-level jazz musicians in an ecologically valid concert environment. Though the participants were aware that the performance would serve as the basis for a subsequent interview, here they played in a group setting in front of an audience of about 300 people in a small concert hall. As in my previous study, an attempt was made to create approximate notation for the violin, piano, and bass parts. However, the technology did not cooperate and most of the interview was based on audio prompts only.The methodology was as follows. The four musicians were asked to play an improvisation on a selected blues theme. They chose the blues composition, Sonnymoon for Two, by jazz saxophonist Sonny Rollins. The drummer was given a click track set to metronome 200 in a pair of headphones but was asked to take the headphones off as soon as the performance started. The tempo was therefore not necessarily constant. The performance was recorded on four separate tracks representing the four instruments violin, piano, bass, and drums into a computer using standard multitrack recording software ("Logic Pro," 2012). The first three were recorded using a direct line signal instead of individual microphones to eliminate cross talk. The drums were recorded with two overhead microphones.After the performance, the musicians were seated in a row on one side of the stage and interviewers on the other about 10 feet away. …