It is well known that jazz improvisations include repeated rhythmic and melodic patterns. What is less understood is how those patterns come to be. One theory posits that entire motor patterns are stored in procedural memory and inserted into an ongoing improvisation. An alternative view is that improvisers use procedures based on the rules of tonal jazz to create an improvised output. This output may contain patterns but these patterns are accidental and not stored in procedural memory for later use. The current study used a novel computer-based technique to analyze a large corpus of 48 improvised solos by the jazz great Charlie Parker. To be able to compare melodic patterns independent of absolute pitch, all pitches were converted to directional intervals listed in half steps. Results showed that 82.6% of the notes played begin a 4-interval pattern and 57.6% begin interval and rhythm patterns. The mean number of times the 4-interval pattern on each note position is repeated in the solos analyzed was 26.3 and patterns up to 49-intervals in length were identified. The sheer ubiquity of patterns and the pairing of pitch and rhythm patterns support the theory that pre-formed structures are inserted during improvisation. The patterns may be encoded both during deliberate practice and through an incidental learning processes. These results align well with related processes in both language acquisition and motor learning.

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