An investigation was made of the Guilford-Martin and Bernreuter personality inventory question mark scores of several hundred naval aviation cadets in an effort to determine the reliability and relationship of these responses to personality and intelligence. The question mark scores from these tests were correlated with the Guilford-Martin trait scores, ACE scores, and years of schooling. Results indicate that the tendency to respond by question mark is a reliable trait as evidenced by the relatively high intercorrelations between the number of such responses from the tests used. The question mark scores were independent of intelligence. The conclusions recommend that personality trait scores should be adjusted by a factor representing the number of times the question mark category is used and the scoring procedures followed with respect to this category.