Explorations of crystallized intelligence: Completion tests, cloze tests and knowledge

An attempt is made to reconcile two historically important tools for the assessment of intelligence and the prediction of academic achievement with extant theories of verbal-crystallized-knowledge aspects of adult abilities. A study of 167 adults (aged 18-69 yrs) reasserts the importance of individual differences in completion test and cloze test performance in accounting for both measures of crystallized intelligence (Gc) and four scales of knowledge (biology, US history, US literature, and technology). The completion tests were found to account for all of the variance in Gc and knowledge that the cloze tests accounted for, and resulted in incremental predictive validity for both domains. In addition, completion and cloze tests were found to have a suppressor effect on the relationship between Gc and Age. We note that C. Spearman’s (1927) assertion, namely that the completion test had higher correlations with intelligence than any other measure. Our results suggest that abstract reasoning may be far less useful in predicting learning and performance than the completion test is.