What is the correlation between WISC & WIAT scores? If a person scores > 99.9% on VC in WISC ( over 160 for extended score) but only scores 99% (130+) on reading in WIAT, what does it mean? Does it mean that the person has not been worked to his/her potential yet? Is it considered an area of under-achievement? Especially if the person really loves reading and etc together with such a strong IQ score, why is the achievement test result not at the same range?