For NDDs = so normally, in TD children, they perform similarly on all the diff tasks. But in NDDs, the performance on each task is diff e.g., autistic kids have savant skills. So IQ is seen in the normal distribution, and in some NDDs we want to see full IQ score bc we expect them to have learning disability (low IQ), but in some other NDDs, i.e., "specific disorders", we expect them to have normal IQ but specific impairments in some skills, e.g., dyslexia, ASD, etc. So full IQ scores are meaningless, there's an uneven cognitive profile in many NDDs (both strengths and weaknesses) which is masked by an average full IQ score - so it's better to look at the 5 primary index scores for NDDs to really see where they're overperforming & underperforming compared to TD