This study analyzed a number of problem solving behaviors that might contribute to an understanding of age and IQ differences in performance on the Block Design Subtest of the Wechsler Intelligence Scale for Children-Revised (WISC-R). The performance of 97 second graders and 99 fifth graders was videotaped as they completed the WISC-R Block Design Subtest. The behaviors coded from the videotape included the time taken to construct each design as well as the time taken to place each of the first four blocks in each construction. The number of block moves made in the construction of each design and the number of eye scanning movements made during the construction of each design were also assessed. The results showed that both developmental and individual differences exist in the skill and efficiency with which children solve WISC-R Block Design items. The fifth grade children appeared to apply more efficient solutions than the second grade children. The fifth graders made more moves in less time across increasing levels of item difficulty. Children in the high estimated IQ (EIQ) group were the most efficient and systematic problem solvers. The children in the low EIQ group were characterized by the use of a more impulsive response style. The results of this study were also found to support Wechsler's (1974) assertion that the WISC-R Block Design items are ordered so that each successive item is more difficult to solve than the one before it. This study presents a method for the analysis and interpretation of overt differences in student performance on the WISC-R Block Design subtest
