I Summary

Although the origins of many of the trends culminating in the experimental psychology of 1860 and beyond can be seen in Greek and pre-Renaissance thought, it is primarily the history of ideas since the Renaissance that casts light on the academic and intellectual Ortgeist and Zeitgeist of mid-19th-century Europe, where experimental psychology was born.

Five major lines of development from science contributed to the birth of experimental psychology about 1860. In physiology, there were the rediscovery of the anatomical distinction between sensory and motor nerves, the study of the electrical nature of the nerve impulse, anatomical and functional studies culminating in the neuron theory, the controversy concerning the localization of functions in the brain, the doctrine of specific nerve energies, and extensive research in sensation. Biology contributed the careful study of morphology and, to a lesser extent, behavior; the most important influence from biology was the concept of evolution. Atomism was a prevalent and useful approach in physics, chemistry, and other fields, and therefore many people tried to be atomistic in the analysis of mental phenomena too. The desirability of quantification was very' much in the Zeitgeist; study of the personal equation led to mental chronometry and the study of reaction time, descriptive and inferential statistical tools were developed, and the psychophysical methods grew out of the attempt to quantify mental events.There was a strong tendency to establish formal research and training laboratories in the natural sciences.

Three major trends in philosophy influenced the newly developing science of psychology. Critical empiricism, with roots in Greek and Renaissance thought and carried on by the new philosophers—among whom Descartes, Locke, Berkeley, Hume, and Kant stand out—examined the important question of how one can acquire knowledge. Associationism, begun by Aristotle and taken over particularly by the British philosophers of the 18th and 19th centuries, attempted to explain how ideas hang together. Scientific materialism had its modern origins in Descartes, was picked up in particular by French philosophers, but was also contributed to by British and German thinkers; one of its chief tenets is that mind and behavior are part of the natural world and can be described and studied just as scientifically and materialistically as any other phenomena.

It was, then, out of scientific developments in physiology and biology, the establishment of laboratories, and the tendency toward quantified atomistic thinking as well as the philosophical views of associationism, critical empiricism, and scientific materialism, that the new science of experimental psychology arose.