TABLE I 



Threshold Quantities for Human Acquisition of 



Speech: Age and Brain Weight^ 



^ Lilly, John C. Man and Dolphin: A Developing Relationship. London: Victor Gol- 

 lancz, 1962. 



"Boston Children's Hospital data from 1,198 records, in Coppoletta, J. M., and 

 Wolbach, S. B., "Body Length and Organ Weights of Infants and Children," American 

 Journal of Pathology, IX (1933), 55-70. 



^ Summarized from McCarthy, Dorothea, "Language Development in Children," in 

 Carmichael, Leonard, ed.. Manual of Child Psychology. New York: John Wiley, 1946, 

 pp. 476-581. 



Table i shows relations between age, brain weight, and speech 

 performance, up to 23 months, 1070 grams, and the use of full 

 sentences. By 17 years, the brain reaches and levels ofl at 1450 

 grams and the number of words, levels of abstraction, etc., are so 

 large as to be difficult to assess. 



In these processes, what are die minimum necessary but not 

 necessarily sufficient factors?'" On the biological side, modern 

 theory concentrates on two factors: total numbers of neurons 

 and the number of interconnections between them. On the psy- 

 chological side, modern theory concentrates on the numbers of 

 occurrences of reinforced contingencies experienced, the num- 



48 



