In general, it has been found that unschooled children succeed at the Piagetian tasks at somewhat later ages than the children studied in Geneva. Also, IQ results do not seem to correspond to the levels of
reasoning obtained by means of the Piagetian tasks. However, very little is known about the reasons for differences in speed of cognitive development, and as yet, few attempts have been made to find out whether differences in stimulation by the environment in general and schooling in particular affect only the speed or also the course of development. Does the development of the fundamental mental op erations follow one particular pattern, regardless of the type and amount of schooling a child may receive, or, on the contrary, are there different ways of acquiring a particular type of reasoning?