Charles Spearman and L. L. Thurstone were pioneers in the field of intelligence. They not only developed methods to assess and understand intelligence, but also developed theories about its structure and function. Methodologically, their approaches were not that distinct, but their theories of intelligence were philosophically very different --…

The assessment of cognitive ability in students with the most severe disabilities presents a challenge to the clinicians who are charged with this task. This article is the second of a two-part series that summarizes what is currently known about effective assessment of the cognitive ability of students with significant impairments in order to…