Average iq for different ages
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Average IQ for Different Ages
Childhood IQ Trends
Early Childhood IQ Stability
Research indicates that IQ scores in early childhood can be predictive of later intelligence. A study following individuals from ages 2 to 19 found that most adults who scored in the intellectual disability range also had low scores as children, while those with average scores in adulthood had similar scores by age 3. This suggests a degree of stability in IQ from early childhood.
IQ Development from Preschool to Adulthood
A longitudinal study assessed IQ from preschool to early adulthood, showing that intellectual ability remains relatively stable over time. The study found that children with initially higher IQ scores maintained their advantage into early adulthood. This stability was more pronounced for children with lower IQs compared to those with higher IQs.
IQ Changes During School Years
Sex Differences in IQ
A longitudinal study examining sex differences in intelligence found that girls had a slight IQ advantage at ages 7 and 11, but by age 16, boys had a slight advantage. This shift suggests that while early childhood IQ may favor girls, boys may catch up and surpass girls in later adolescence.
Predictive Power of Childhood IQ
IQ scores between ages 3 and 18 have been used to predict educational and occupational outcomes in adulthood. By the second grade, these predictive correlations were similar to those obtained with adult IQs, particularly for occupational status . However, the correlations were not strong enough for practical long-term predictions for individual children .
Adolescent IQ Trends
Flynn Effect Variability
The Flynn Effect, which describes generational increases in IQ, shows variability across different ages and ability levels. A study of American adolescents aged 13-18 found that while IQs increased by 2.3 points at age 13, they decreased by 1.6 points at age 18. This suggests that the Flynn Effect may not be uniform across all age groups and ability levels.
IQ Comparability Across Tests
Research comparing seven widely used intelligence tests found substantial correlations at the group level but significant mean differences at the individual level. This indicates that while group-level IQ trends can be reliably compared, individual IQ scores may vary significantly depending on the test used.
Adult IQ Trends
Heritability of IQ
The heritability of IQ increases with age, reaching an asymptote of about 0.80 at ages 18-20 and continuing at that level into adulthood. Shared environmental influences decrease with age, approximating about 0.10 by adulthood. This suggests that genetic factors play a more significant role in determining IQ as individuals age.
IQ and Aging
Older adults (aged 60-79) show increased variability in IQ-related tasks compared to younger individuals. However, their ability to time events accurately remains intact, indicating that while some cognitive functions may decline with age, others remain stable.
Conclusion
IQ shows a degree of stability from early childhood into adulthood, with some variations based on sex, age, and ability levels. While early childhood IQ can predict later outcomes, the predictive power is not strong enough for individual long-term predictions. The heritability of IQ increases with age, and while older adults may experience increased variability in certain cognitive tasks, their overall timing abilities remain accurate.
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