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During the 20th century , starting with the often criticised but nonetheless important work of G. Stanley Hall , who " promoted the link between the study of development and the ' new ' laboratory psychology " , and especially with the work of Jean Piaget , who " saw cognitive development as being analogous to biological development " , it became understood that the psychological development of children occurs in stages and that their capacities differ from adults .
 G. Stanley Hall, Jean Piaget
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
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Answer:
 G. Stanley Hall, Jean Piaget