On the development of early conditioned reflexes and differentiations of auditory stimuli in infants.

Abstract

Three children, aged 11 days to 1 month (at the beginning of experimentation) were used as subjects in these studies. The chief findings and conclusions are summarized as follows: "(1) The conditioned alimentary reflexes, in response to auditory stimuli, appear in the first half of the second month of the human infant's life. (2) There are three stages in the development of the conditioned auditory reflexes: (a) the stage of indifference, (b) the inhibition of movements and the appearance of the first signs of conditioned reactions; (c) the stage of a clear conditioned reaction. (3) In the formation of the conditioned auditory reflex the main role is played by the child's age and not by the number of stimulations. (4) The sucking movements are the most convenient and simple indication of the conditioned alimentary reflexes in the first three months of the child's life. (5) At the age of 2½ to 3½ months the child is able to differentiate as small a difference as 11½ tones, as indicated by the method of conditioned reflexes. (6) At the age of 4 months and 4 days the differentiation amounts to 5½ tones. (7) There are considerable individual variations even in the formation of the simplest auditory differentiation. (8) In its formation the first differentiation formed passes through the following stages: (a) an absence of differentiation; (b) the stage of unstable differentiation, and (c) the presence of differentiation. (9) The formed auditory differentiation, being stable enough, still may disappear under the influence of certain outer and inner factors. (10) The presence of a differentiation suggests a complication of the cerebral functions with the age of the child." (PsycINFO Database Record (c) 2006 APA, all rights reserved)