First, third, fifth and eleventh graders were videotaped as they completed the Block Design Subtest of the WISC-R. Neither the order of placement of blocks within each design nor the degree to which children persisted in placing a given block correctly before moving to the next one evidenced developmental differences. (Author/RD)

Various experiments demonstrated that the difficulty level of several performance-type intelligence test tasks is determined directly by stimulus and task variables that vary the information to be processed. The implications of these findings for intelligence and the problems of an experimental approach to the measurement of intelligence are…