Does the Defining Issues Test measure psychological phenomena distinct from verbal ability? An examination of Lykken's query.

This study examined the incremental validity of the Defining Issues Test (DIT), a test purporting to measure moral reasoning ability relative to verbal ability and other major markers of the construct of general intelligence (g). Across 2 independent studies of intellectually precocious adolescents (top 0.5%), results obtained with the DIT revealed that gifted individuals earned significantly higher moral reasoning scores than did their average-ability peers; they also scored higher than college freshmen, who were 4 to 5 years older. The relative standing of the intellectually gifted adolescents on moral reasoning, however, appears to be due to their superior level of verbal ability as opposed to any of a number of the other psychological variables examined here. The hypothesis that the DIT is conceptually distinct from conventional measures of verbal ability was not confirmed. Investigators conducting subsequent studies involving the assessment of moral reasoning are advised to incorporate measures of verbal ability into their designs, thereby enabling them to ascertain whether moral reasoning measures are indeed capturing systematic sources of individual differences distinct from verbal ability. This idea also is relevant to other concepts and measures purporting to assess optimal forms of human functioning more generally (e.g., creativity, ego development, and self-actualization ).