INTELLIGENCE 9, l 11-136 (1985) Information Processing Components of Substitution Test Performance* LILA F. LAUX AND DAVID M. LANE Department of Psychology Rtce Umverstty P.O. Box 1892 Houston, TX 77251 Although substitution tests have been included in tests of mtelhgence for years, the underlymg abdmes they measure have stall not been clearly determined This study used componentml analys~s to mvestlgate the mformatton-processmg components underlymg substitution test performance The bases of sex and age differences were also of interest One hundred subJeCts from each of three age groups (9-11. 18-25, and 60-89 years) were tested The componentlal analysis found that subsUtutlon tests measure perceptual speed and, to a lesser extent, memory ablhty and writing speed The component "Sumulus Onentat~on, Response Inltmtlon, and ExecuUon" was related to substitution test performance m the sample of chddren and the sample of older adults but not m the sample of younger adults Verbal abdlty was not slgmficantly related to substitution test performance m the two younger samples but was strongly related to substitution performance tn the oldest sample Although females outperformed males on the Symbol D~glt Test, males &d as well as females on the computerized tasks Appar- ently, sex differences in substltuaon test performance cannot be explained by the components of the test measured here INTRODUCTION Substitution tests such as the Digit Symbol Subtest of the Wechsl~r Adult Intel- ligence Scale (WAIS), the Army Beta Substttutton Test, and the Coding Subtest of the Wechsler Intelligence Scale for Children (WISC) are among the oldest and best established of all psychological tests and are currently included m many widely used intelligence measures (Matarazzo, 1972). These tests are rehable, easily and qmckly admimstered, relative culture free, and simply and objectively scored. The Digit Symbol Subtest of the WAIS patrs the &gits 1-9 with nine sym- bols; the task is to enter the appropriate symbol into the empty square beneath the *This research was supported by National Insutute of Health Grant # IR03 MH 36551-01 to David M Lane Requests for reprmts should be addressed to David M Lane at the address hsted above 111