Dysgraphia and dyslexia are going to impact any subtest which requires a child to use a skill that is impacted by either dysgraphia or dyslexia. I am not familiar enough with dyslexia to give you a list of subtests for either the WISC or the WJ-III Cog. that might be impacted - I don't think either test requires a child to actually read any of the questions, but there are subtests that require visual ids. My dysgraphic ds has taken both the WISC and the WJ-III Cognitive Abilities tests - his FSIQ (called "GIA") on the WJ-III was very close if not a little bit higher on the WJ-III than his GAI is on the WISC. The one WJ-III subtest that was impacted by his dysgraphia was visual matching, and on the WISC the subtest score that was impacted was coding. Although there is no "GAI" on the WJ-III there are a larger number of subtests that go into calculating the "GIA" - hence I think the impact of the one very low subtest wasn't as great as it would be on the WISC.
Re the scores coming out lower than you expected, remember that no child is defined by one test score. It's possible that with a different day, a different tester, etc your ds will have a much higher score - or maybe not. Even if he doesn't, that doesn't mean he isn't all that you've seen in him to this point
And fwiw, my dd who has a challenge that impacts her ability to read (but does not have dyslexia) had much lower scores on the WJ-III than I would have anticipated based on just knowing her. She's also struggled more and more as time goes on so sometimes I wonder if her scores would have been higher when she was younger. She hasn't had the WISC (yet) but on the WJ-III Cog. the one subtest that was substantially lower was associative memory (I can't remember the exact name of the subtest). Her reading-assessment type tests have scores that are mostly very strong except the subtests impacted by that one ability.
"I can say that, compared to DD, he doesn't have her vocabulary. That is where I can see her verbal gifts in spades. But he finds patterns so quickly! When we are doing puzzles of some kind, he is the one who will grasp it the fastest." I suspect dyslexia is coming into play here - no matter how many audiobooks your ds has listened to or how many deep conversations he's been a part of. I've found that vocabulary growth for my dd with the reading challenge seems to be slower than I would have anticipated based on just "knowing her".
"The tester also said that his visual memory was poor. Again, I'm not sure if this could affect his score. What I see from him academically is that he can be quite advanced in math, etc. He is working 1.5 grades ahead, and catches on to concepts quickly, but has trouble retaining procedures, so he can astound me with how quick he is one day, and the next day, it is like he forgot what he was doing the day before."
This is also a lot like my dd with the reading challenge.
"FWIW, my son has more gifted personality traits than DD. He can be somewhat intense, with obsessive interests, and has some OE's."
I am a bit of a skeptic about the lists of "gifted traits" - not because they don't exist in gifted children, but because they can exist in children who are not gifted too. My EG child is not my most intense child - not by a longshot. I have known children with obsessive interests who are not gifted or anywhere near it. Same goes for the OEs. So while I think you will find gifted children who have lots of the "gifted traits" checked off on those types of lists, I think you'll also find gifted children who *don't* fit those lists all that neatly. If you didn't know my ds well, he absolutely would not at first glance appear to be the EG child in my family, but my reading-challenged dd often does appear EG - until she has to do schoolwork lol!
Hope some of that helps -
polarbear
ps - I actually like the WJ-III Cog test better than the WISC for children with LDs - both because of the number of subtests and because of the way it can be paired with the WJ-III Tests of Achievement to further define areas of strength and weaknesses.
