First, I want to state up front that the info I have is mostly taken from this book "A Parent's Guide to Gifted Children" by Webb, Gore, Amend and DeVries. This is truly an exceptional book - it is a must-have for all parents of gifted kids. It's well-researched and answered all the questions I had clearly and comprehensively. I've read other books on gifted kids, but none even came close to matching this one - it gets the gold star.
Some basic information (and common misconceptions):
There are many types of giftedness.
Gift in the arts, in sports, in leadership, etc. For purposes of the GEP, we are refering specifically to the intellectually gifted. However, while as a group, these kids have high IQs, they are not necessarily super in every academic subject.
Giftedness is generally inborn.
In other words, you're either gifted or you're not. However, environment does play a role. A supportive and nurturing environment up to the ages of 7 or 8 can increase IQ scores of 20 points or even more. But generally, test scores for giftedness will remain pretty much stable by the time the child is 8. Because of this, the recommended age for intelligence tests in schools is 8 or 9, otherwise time would have been wasted with gifted kids having their talents unidentified and untapped (The Singapore MOE has probably read all the research, that's why they do the GEP tests in P3!)
Being gifted and being "smart" is not the same thing.
People have often argued that the GEP is discriminatory because there are late bloomers who do pretty well later on in life. I think this arises because there is a confusion between being gifted and being smart. It's probably safe to say that all gifted children are smart, but not all smart children are gifted. Research shows that in general, about 1% of each cohort is intellectually gifted. Again, MOE follows this closely, the top 1% of each P3 cohort who take the selection tests are offered the GEP.
Those are the basic parameters. So we go back to the question, "how do I know if my child is gifted?" Here are but some of the common characteristics as listed in the book mentioned above, and my own experience with Lesley-Anne (ala how I was finally convinced she's gifted).
1) Strong verbal abilities from a young age. Many gifted kids start talking and reading early. Some on the other hand, start later but when they do, it's with astonishing maturity and complexity. Lesley-Anne didn't speak until she was way over 2 years old, but then she spoke in whole sentences and her understanding of instructions was very good even at age 1. In pre-school, her teacher commented that she "spoke like an adult". Gifted kids also usually have large vocabularies and can distinguish between similar words like "angry" or "irritated".
2) Overactive imagination and creativity. Gifted kids tend to like experimenting and can flit from one interest to another. They can live in an imaginary world with imaginary friends and imaginary pets. When she was 5, Lesley-Anne told me she had a new best friend in school called Sally. I got curious when she told me Sally was the same height, same weight, had the same haircut as her. I called the school and found out there was no such person!
3) Extreme sensitivity and intensity. This one really hit home when I read about it. I was despairing over Lesley-Anne because she was truly the most sensitive child I had ever come across. Every word could be deemed a criticism. She would be hurt by seemingly harmless gestures and any sort of unfairness would cause an intense reaction. When she was about 3 and watching Bambi on video, she burst into tears when Bambi's mother was shot and kept asking me why the hunter had to shoot her. From then, everytime she watched the cartoon, she would fast forward that scene. Even today, when she has learned to reign her emotions better, I would get comments from her piano teacher: "Aiyoh, just told her what she played wrong and the tears started flowing! I can't bring myself to scold her."
4) Super learning ability and memory. The difference between gifted and smart children are that while both can learn new things quickly, the smart child tends to learn age-appropriate things. Gifted children, on the other hand, have been known to grasp concepts way beyond their years. One of Lesley-Anne's classmates had finished reading Tolkien's Lord of the Rings several times over by age 9 and at 10, was poring over adult astronomy reference books. They also tend to have great memories. I remember watching Jumanji on tv with Lesley-Anne when she was 7. Before the next scene, she would tell me what would happen and even spout the exact words the actor would say. All this she remembered from watching the show ONCE when she was 4.
5) Need for reasoning and rationality. Gifted children tend to question everything and they need to have answers that satisfy their intelligence. The worst possible thing I can say to Lesley-Anne when she questions my instruction is: "Because I said so." This sort of autocratic answer with no logic upsets her, she needs to see the reasoning behind it. Once, she accidentally scalded her fingers on hot soup. When the pain had not abated after putting ice on her fingers, I offered to give her a dose of paracetamol. She immediately asked to know how paracetamol would work since it was to her, a medicine for fever. When I said it numbed the pain sensors, she questioned how it would know to numb the ones in her fingers and not anywhere else. All this while she was in pain. Basically, gifted kids are unlikely to take anything at face value, they will question you to death if necessary.
There are several other characteristics, but it would be too long to list everything. This is a summarised version. If you want to know more, I really recommend you get the book!
Finally, I just want to stress that giftedness is a blessing. If your child has it, embrace it. But he cannot claim credit for it anymore than a child born into a rich family can boast about having earned his wealth. And at the end of the day, it's not about possession but what you do with the giftedness that counts.