Principles of Psychology - Nineteenth Century Experimental Results

Nineteenth Century Experimental Results

The opening of Principles, after introductory material, presented what was known at the time of writing about the localization of functions in the brain—how each sense seemed to have a neural center to which it made report, and how varied bodily motions have their sources in still other centers.

The particular hypotheses and observations on which James relied are of course very much dated. But the broadest conclusion to which his material leads is still valid: that the functions of the "lower centers" (beneath the cerebrum) become increasingly specialized as one moves from reptiles, through ever more intelligent mammals, to humans, while the functions of the cerebrum itself become increasingly flexible, less localized or specialized, as one moves along the same continuum.

James discussed experiments on illusions, too (optical, auditory, etc.), and offered a physiological explanation for many of them, that "the brain reacts by paths which previous experiences have worn, and makes us usually perceive the probable thing, i.e. the thing by which on previous occasions the reaction was most frequently aroused." Illusions are thus a special case of the phenomenon of habit.

Principles is an important source for the history of psychology in the 19th century. In Chapter 7, James suggests that Weber, Fechner, Vierordt, and Wundt might be the greatest experimental psychophysiologists of the 19th century.