Modelling how people establish a sense of tonality and encode pitch invariance are important elements of research into musical cognition. This paper describes simulations of processes that induce classifications of pitch and interval use from a set of nursery-rhyme melodies. The classifications are identified with keys and degrees of the scale. The extractive process has been implemented in various forms of shunting, adding and tracking memory, and ART2 networks, Kohonen feature maps and feedforward nets are used as classifiers, in modular combinations. In the model, stable tonal centres emerge as general categories of pitch use over the short to medium term, while degree categories emerge from classifying interval use over the longer term. The representations of degree reflect the similarity relations between degrees. Overall, this research is concerned with the problem of how to abstract representations of sequences in a way that is both resilient and adaptive. It uses various extractive processes cooperatively to derive consistent representations from sequences of pitches, and shows that by using information generated within one process it is possible to guide the development of another, in this case functional representation.