An unfolding model was selected for the scores on the Scale of Intellectual Development to take into account that, for stage-based instruments, agreement with a statement first increases as the student approaches the stage represented by the statement, then decreases as the student progresses beyond that stage. (Contains 21 references.) (Author)

A student development instrument, the Scale of Intellectual Development (SID), designed to measure a model of cognitive development. Validated the instrument with a sample of college freshmen (N=3,321). Results suggest that the SID has promise as a student development instrument; however, additional validation evidence needs to be collected. (RC)