JEAN PIAGET

Jean Piaget born in Neuchâtel (Switzerland) on August 9, 1896, studied
natural sciences in the college of Neuchâtel.  This is where he recieved
his Ph.D.  At the age of 11, at Neuchâtel Latin high school, he wrote an
essay of an albino sparrow which started his long succesful career.

Piaget world famous for child congnition created the principle for ageing
infants.  Sensorimotor(first phase 0-2[years]), preoperational(second
phase 2-7[years]), concrete(third phase 7-11[years]), and lastly formal
operations(12+[years]).  Hes most famous for studying and answering the
question how does knowledge grow.  answer is that the growth of knowledge
is a progressive construction of logically embedded structures superseding
one another by a process of inclusion of lower less powerful logical means
into higher and more powerful ones up to adulthood.

http://www.piaget.org/biography/biog.html