Thesis (Ph.D.)--Boston University. / This thesis examined the relationship between thinking dominated by perception and thinking guided by logic. It was suggested by Piaget's theory of cognitive development which defines modes of thinking in terms of logical forms as models of operation of the mind. Thus thinking unfolds in several stages, each characterized by a precursor of logic. Within this theoretical framework, the present study focussed on the supremacy of misleading perception at the onset of the concrete operational stage. The relationship was examined in a situation of incompatibility between perception and logic [TRUNCATED]