ABSTRACT
In the case of adults and older children, the strategy to be followed can be communicated verbally, its implementation being perfected by practice. When the psychologist compares results on a given task obtained from groups of children of differing ages, the improvement in performance appears to be progressive, the slope of the developmental curve being more or less steep depending on the task concerned. During the various stages of childhood the number and importance of the changes observed is particularly impressive. The child’s responses are organised in terms of coherent systems called models. As the child grows, under natural conditions of stimulation, new, acquired structures are added to those which are predetermined and modify them slightly. The youngest children hardly relate any but a very few elements which are close together, as is shown by the restricted extent of their visual displacements and the relatively circumscribed area of their useful field of fixation.
