Many researchers, wishing to generalize to large numbers, have turned away from Piaget's measurement techniques to group paper-and-pencil tests. The psychometric properties of these tests and their statistical links with other constructs are examined, along with the relationship between the observed products of mental effort and their underlying…

This article considers relatively neglected resources for the "bootstrapping" of cognitive growth, including chance plus selection, the affective boosting of relevant schemas, the operation of innate biases, and use of spare mental capacity. Implications for educational research are illustrated with reference to recent work on the…