ABSTRACT
The period of modern experimental physiological psychology may be dated from the publication of Brain Mechanisms and Intelligence in 1929. Karl Spencer Lashley formulated neuropsychological problems which he attacked with the new methods that he developed in the laboratory; he set exacting standards of analysis which themselves became the standards of contemporary brain ablation research. And he summarized the results of his now-famous brain ablation experiments on rats which he conducted in Chicago in the 1920s. Lashley's emphasis on standard procedures of testing was important because it permitted verification of data and replication of experiments. Lashley's early diagrams of brain lesions did not prove to be satisfactory; these were based on camera lucida drawings of the fixed brain, prepared in 1917 with Franz. Then, in 1921, Lashley described a method of reconstructing the lesion from histological material. Serial frontal sections of the brain were prepared, stained in iron hematoxylin, and mounted in balsam.
