What shapes a man's ability and skill was always a question to psychologists until a few decades ago when findings show that they for the most part come from practice ---- repetitive and endless practice.  The psychologist K. Anders Ericsson of the University of Florida and his team, based on a survey of a violin class in a college of music, have found that the students whose levels are rated as "A" have spent on average over 10,000 hours on violin-practice, those with level B a bit less than 8,000 hours, and those with average or lower levels no more than 5,000 hours. The result of the survey is widely preferred because it suggests that practice makes perfect, that is, the distinction between "excellent" and "good" lies more in hard work than in natural intelligence. Malcolm Gladwell points out in his latest book Outliers: The Story of Success: "Practice isn't the thing you do once you're good. It's the thing you do that makes you good." Besides, he thinks IQ plays little part in the formation and development of ability. "When one has an IQ of 120," writes he, "what is beyond it does not make an evidential difference in real life."  However, scientists' experimental results are quite different from the psychologists'. Their findings show success in many areas depends on intelligence --- and not a little. David Lubinski and Camilla Benbow of Vanderbilt University, with their research group, carried out a milestone research. They selected from Youth Talented Search 2000 teenagers of or under 13 whose SAT results ranked top1%. After tracking the achievements the 2,000 "wonder children" made in academy and career, Lubinski and Benbow's group found that those ranking top 1% have more possibility (averagely by two to four times) to get a doctor's degree, a certificate, and publish academic theses and works than those ranking top 9%. As a conclusion, it's a great advantage in the real world to have a high IQ. Psychologists' conclusion is popular among people probably because   _  .
everyone sees a chance to succeed through practice hard work plays as important a part in success as IQ they are told that IQ makes no difference in real life there is no difference between "excellent" and "good"