This is part 2 of 5 in the series Brain - Time - Music - Computing.
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Even though perpetual contingency characterizes Middle World, the underlying dynamics are not random. On the contrary, their complexity thinly veils a rich variety of spatio-temporal patterns . The term pattern, here, denotes “a regular and intelligible form or sequence discernible in certain actions or situations; esp. one on which the prediction of successive or future events may be based” (Oxford English Dictionary). Under such conditions, the brain has evolved into a highly effective spatio-temporal pattern detection and prediction system . Moreover, the brain exhibits an “infovorous” behavior : it craves for new experiences. More specifically, studies have linked sensory novelty and surprise to pleasure and reward activity in the brain. This is consistent with the continuous reﬁnement of the prediction system through acquisition of new knowledge.
Both the creation and performance of music play directly into these fundamental brain mechanisms , taking advantage of the pleasure systems wired in the brain. From rhythmic patterns to more intangible tonality systems, the brain naturally picks-up, processes, and responds to, spatio-temporal structures in music. If too predictable, a piece of music or a performance are simply boring; on the other hand, the listener might not be able to make sense of a piece or a performance that is "too" unexpected. The art of creating music, or any other artifact intended to stimulate human interest, hinges on striking a delicate balance between familiarity and surprise; establishing a frame of anticipation, and venturing outside of this frame in such a way that prompts the listener to adapt her own frame of reference.
These observations point to a highly dynamic notion of music making and listening. If the musical expertise, and expectations, of brains change every time they experience music, then what constitutes interesting music and interesting performance changes constantly, both at the individual and at the cultural levels. The computational modeling of such concepts as musical appreciation must therefore characterize how context, both individual and collective, plays out in the dynamics of the particular perceptual and cognitive processes involved.
 I. Biederman and E. A. Vessel. Perceptual pleasure and the brain. American Scientist, 94:249–255, 2006.
 Jeff Hawkins and Sandra Blakeslee. On Intelligence. Times Books, 2004.
 David Huron. Sweet Anticipation: Music and the Psychology of Expectation. MIT
 Ken Richardson. A Mind for Structure: Exploring the Roots of Intelligent Systems.
Brown Walker Press, 2006.