The NNAT-2 is a single task, most closely resembling the Matrix Reasoning subtest from the WISC. Adding in the scantron aspect of administration, processing speed-related factors do enter, depending on the reasons for his low PSI. Even if he didn't make errors entering his responses, the additional effort of visual scanning, discrimination, and bubbling may have slowed him down, leaving him less time to reflect on and complete downstream items. It's also often administered in a group setting, which may affect children who are not as efficient at screening out background noise or visual distractions.
Was there ever any follow-up on his low PSI? Though solidly Average, it is markedly lower than his GAI index scores.
