ABSTRACT
Most perceptive reactions of a spatial nature are congenitally predetermined, as we have noted. The localization of a cutaneous excitation, of a light or sound stimulation, is defined by motor reflexes of the limbs, of the head, and of the eyes, disclosed among the new-born in a very precocious fashion. But, if the reflexes continue to be produced under the same circumstances there will never be that adaptive plasticity characteristic of psychological functions, which requires the acquisition of experience. Whether congenital perceptive reactions were first acquired by trial and error or by chance variations in the physical-chemical structure of the germs, is a problem like all questions of origin which escapes investigation. 1 But we observe, during the life of an individual, the pre-existing reactions developing, becoming more perfect and more flexible, and the birth of innumerable new reactions.
