A small percentage of the populatio

A small percentage of the population has direct access to pitch information in the form of linguistic codes that they can apply to pitches. Research in this area suggests that access to some of this information might exist in a much larger proportion of the population. Infants appear to be born with the capacity to attend to and make use of absolute pitch information in melodic recognition tasks, although general development or musical training causes a strategic shift towards relative pitch processing in most normally developing (as opposed to developmentally delayed) individuals. Those who do acquire absolute pitch most probably do so within a critical period of development; they might have a genetic or neural predisposition to do so (Box 3), but some form of system atic training appears to be necessary (see also Box 4). Neuroanatomical studies have confirmed differences between AP possessors and non-possessors, although cause and effect have not been distinguished. New work on the neuroanatomy of pitch memory may yield additional clues. Understanding both the nature of absolute pitch, and why it occurs in some individuals and not others, might tell us more about how humans process melodies and pitch, and has already informed work on perceptual expertise and memory, and theories about cognition, perception, and the interaction between the two