Theories of learning were enormously visible and influential in psychology from 1930 to 1950, but dropped precipitously from view during the next two decades while the information-processing approach to cognition based on a computer metaphor gained ascendancy. The groundwork for a resurgence of learning theory in the context of cognitive psychology was laid during the earlier period by the development of a subspecialty that may be termed mathematical learning theory.

In psychology, just as in physical and biological sciences, mathematical theories should be expected to aid in the analysis of complex systems whose behavior depends on many interacting factors and to bring out causal relationships that would not be apparent to unaided empirical observation. Mathematical reasoning was part and parcel of theory construction from the beginnings of experimental psychology in some research areas, notably the measurement of sensation, but came on the scene much later in...