Trending upward on an IQ test might make even more sense for a young HG+ kid, because of psychological factors such as perfectionism that might be overcome as the child gets older, but also because reaching the child's limit on certain tests might take significantly longer than for an ordinary child (and in fact in some cases it seems that kids peter out before showing what they can do). An HG+ young kid might be significantly more able, but without significantly more stamina, and with significantly more performance anxiety.