Extremely high-performing children are also difficult to differentiate due to a ceiling effect tests designers don't include many high-difficulty questions, because the vast majority of people would miss them, rendering such questions pointless. This makes it difficult to sum up their overall intellectual capacity in a single score, according to Cambridge University.
Some children may achieve genius levels in some categories of intelligence, such as spatial reasoning, but perform normally in other categories. Exceptionally intelligent children suffering from attention-deficit hyperactivity disorder or other cognitive impairments may underperform on the tests relative to their true intelligence. Although IQ tests provide a simple and convenient measurement of intelligence, they have some serious limitations.
