Well, the matrix reasoning score makes sense, as the task is more about abstract reasoning and pattern recognition than it is about straight visual skills, although, of course, you have to be able to see the designs to solve them. Likewise, block design has significant motor and motor speed elements, which were probably impacted, and relies on vision to complete, but it also contains spatial reasoning and nonverbal problem solving components that would not necessarily be as compromised by vision issues. The blocks are big enough, and the color patterns distinct enough, that he was probably able to solve the items accurately, with just some points knocked off for speed. Any comments on slow-but-accurate performance, loss of bonus points for speed, or overtime responses? Those are usually tipoffs that the real issue with a relatively lower block design score is motor speed. Sometimes there is also an alternate score reported (it can be generated for any WISC-IV, but not everybody reports it) for block design no bonus points, which is a less-timed version of scoring. There are still time limits for completing each item, but speed is not factored into the scaled score. If you compare the standard bd score and the bd no bonus points score, and they are noticeably different (there are tables for statistical significance), that suggests that motor speed is compromising performance, rather than actual perceptual reasoning. Typically, you do not substitute the alternative block design scoring into the Index scores, but it is valuable clinical information.
