Many studies show that the first few years after birth are the fastest period of intellectual development. Some psychologists believe that early childhood is a critical period of intellectual development. Under the influence of good environment and education, children's intelligence develops particularly rapidly at this stage. Psychologist R Pintner pointed out that the period from birth to five years old is the fastest development of intelligence. From five years old to 10 years old, the development is not so fast. But it's still developing. In another five years, development will gradually slow down. American psychologist B.S.Broom thinks that intelligence develops fastest in the first four years after birth, and Swiss psychologist J.Piaget also thinks that the decisive period of human intelligence development is from birth to 4 years old. American psychologist J.S. Bruner also believes that after years of research, from birth to 5 years old.
The results of intelligence test in early childhood are constantly improved with the increase of age, and children's intelligence development is very fast throughout early childhood. In addition, there are obvious differences between urban and rural areas in children's intellectual development. Judging from the scores of each dimension, urban children are generally higher than rural children. The reason for this result is the imbalance of economic and cultural development between urban and rural areas in China. The trend of children's IQ increasing with age has also been supported by other studies.
Some psychologists believe that the limit of intellectual development is 14- 16 years old, but many studies in recent years have denied this view. Some contemporary studies show that intelligence may increase even when people are old, but this growth is limited to one aspect of intelligence and is relatively slow. Professor Zhu Zhixian pointed out: "At present, the problem of the limit of human intelligence development is not very reliable. However, it seems clear that by the age of 18, people's intelligence has reached a mature stage (close to adulthood). After that, with the growth of knowledge and experience, although the total intellectual energy will not increase significantly, some aspects of intelligence may still increase at different speeds. " Generally speaking, people who are healthy, diligent and participate in physical and mental work have slower mental decline, especially nerves. "Intelligence drops rapidly. A study by Bloom et al. shows that language ability usually declines slightly at the age of 80, moderately at the age of 90, and some intelligence continues to grow at the age of 80 to 90. Recently, German anatomist Herbert? The body of Hogg111year-old hogg 165438 was studied. The results showed that the nerve cells in the brain hardly declined with age, but the cell bodies shrank, generally starting from the age of 60 and only 7-8% before the age of 90.