HighIQ - Wanting to respect the OP's thread and not veer off-topic, I will just answer you very briefly:
1) I am not aware of a correspondence table or validity test which correlates the scores of the two tests you mention.
2) Here is a bit of information about WAIS-IV, courtesy of Pearson:
http://images.pearsonclinical.com/images/Assets/WAIS-IV/WAISIV2_6_08.pdf (2008).
3) It seems that you could have the Adult Intelligence Scale (WAIS-IV) administered, if interested to do so?
4) Your post was a bit unclear to me, as to which test you had taken, WISC-V or WAIS-IV:
"Would an adult who maxed out the matrix reasoning test on the WAIS-IV
(sounds like you took the WAIS-IV) max out the the extended norms of the WISC-V matrix reasoning test
(sounds like you are asking what the equivalent childhood scores might've been)? I was able to correctly answer the last question on the matrix reasoning test, so I would have easily maxed the section if I were to take the WAIS-IV
(this sounds like you have not taken the WAIS-IV).
If you wish to discuss this further, please consider creating a new thread, so as to be respectful of the OP's topic of interpreting their child's scores, and not veer off topic, hijacking their thread.
