Psychometric Evidence of Intellectual Growth Spurts in Early Adolescence

A tantalizing idea indicated by both qualitative psychological research and brain research is that intellectual growth includes spurts. Intellectual growth spurts have been difficult to confirm quantitatively because of the lack of a constant unit of measurement for an intellectual variable applicable across different ages and because of problems in conducting longitudinal studies. This article reports quantitative evidence of an intellectual growth spurt during early adolescence by combining (a) modern psychometric modeling that permits transforming discrete responses of persons to test-items into formal measurements, (b) computerized testing with the Raven progressive matrices, and (c) a longitudinal study over 5 years involving 201 students of both genders and from homogeneous socioeconomic and educational backgrounds. No gender differences in the magnitude or the timing of these differences were found although the spurt for girls were clearer than those for boys. The significance of this evidence for educational decisions made during early adolescence is noted, especially in relation to educational assessment and placement.