Eighty-two children (ages 4.4 to 6.5 years) were administered a Backward Digit Span test to measure M-space and four conservation tasks (number, substance, continuous quantity, and weight). Based upon a neo-Piagetian theory of intellectual development proposed by Pascual-Leone (1969), two hypotheses were tested: (1) A significant relation should…

An attempt to train concrete operational fifth-grade students (N=32) and seventh-grade students (N=32) to perform at the formal operational level on tasks demanding the control of variables are reported. The training was conducted in four individual sessions of approximately 30 minutes each. The training sessions were designed to represent a…