A given specialization may occur in more than one

cortical area, although at different levels of efficiency.

More than one area may be able to process the same

information and produce the same or a similar result,

although the precise qualitative nature of the process-

ing, and hence its efficiency (resource use), would

generally differ. This overlap is presumed to arise as a

consequence of the way that the specializations arose

developmentally. Elman and colleagues [1996] suggest

that initial differences at infancy in cell types across

cortical areas can result in some areas gradually becom-

ing more proficient (and hence specialized) in particu-

lar types of processing, namely, those types of process-

ing for which the given cell types are most suited. For

example, cells in more than one brain area may

initially attempt to process speech sounds, but the area

containing cells that are particularly sensitive to the

fine timing distinctions that differentiate phonemes

may eventually become specialized for speech process-

ing. Another area also may have initially attempted to

process speech and eventually lost the competition for

the specialization, but may nevertheless have retained

a residual capability to process speech, albeit less

efficiently. Thus there might be some overlap in func-

tion between areas, such as between the left and right

homologues of the language network.