average iq for every age

Introduction

The study of IQ (Intelligence Quotient) across different ages has been a significant area of research in psychology and education. Understanding how IQ changes with age can provide insights into cognitive development, the impact of environmental factors, and the effectiveness of educational interventions.

Key Insights

Heritability of IQ Increases with Age:
- The heritability of IQ increases with age, reaching an asymptote at about 0.80 at 18-20 years and continuing at that level into adulthood. Shared environmental influence decreases across age, approximating about 0.10 at 18-20 years and continuing at that level into adulthood.
IQ Consistency and Changes in Superior Children:
- Studies show a fair degree of consistency in IQ scores over time, but some large changes do occur. For children with superior intelligence (IQ of 140 or higher), there is a tendency for IQ to decrease with age, with boys losing about 3 points and girls losing about 13 points over six years.
IQ Trends in Adults:
- In adults aged 20 to 74, after controlling for educational attainment, there is no significant decline in Verbal IQ with age. However, declines are observed in Performance IQ and Full Scale IQ across this age range.
IQ in Autism Spectrum Disorder (ASD):
- For individuals with ASD, nonverbal IQ (NVIQ) scores tend to remain consistent from early childhood to young adulthood for those in the average range. However, for those in the lower ranges of ability, actual scores decline from age 2 to 19.
Sex Differences in IQ:
- Longitudinal studies indicate that girls have a slight IQ advantage over boys at ages 7 and 11. However, by age 16, boys tend to have a higher average IQ than girls by approximately 1.8 points.
Historical IQ Gains:
- There has been a significant increase in the mean IQ of Americans from 1932 to 1978, with a total gain of 13.8 points. This trend suggests that representative samples of Americans performed better on IQ tests over this period.

Conclusion

Research indicates that IQ is influenced by a variety of factors including age, heritability, and environmental influences. While heritability of IQ increases with age, environmental factors play a diminishing role. IQ scores tend to be relatively stable over time, though some changes can occur, particularly in individuals with superior intelligence or those with ASD. Additionally, there are observable sex differences in IQ that change with age, and historical data shows a significant increase in average IQ scores over several decades.

Average iq for every age

Summary

Introduction

Key Insights

Conclusion

Sources and full results

The Wilson Effect: The Increase in Heritability of IQ With Age

The heritability of IQ increases with age, reaching an asymptote of 0.80 at 18-20 years of age and continuing at that level well into adulthood, while shared environmental influence decreases across age.

Measurement of Nonverbal IQ in Autism Spectrum Disorder: Scores in Young Adulthood Compared to Early Childhood

Nonverbal IQ scores in individuals with autism spectrum disorder (ASD) generally remain within the average range from age 3 to 19, but actual scores decline from age 2 to 19.

Do the Stanford-Binet Iq’S of Superior Boys and Girls Tend to Decrease or Increase with Age?

Children with IQ scores of 140 or higher tend to lose IQ points over time, while girls tend to gain IQ points over time.

Age and WAIS-R intelligence in a national sample of adults in the 20- to 74-year age range: A cross-sectional analysis with educational level controlled

Intelligence declines in Performance IQ and Full Scale IQ from age 20 to 74, but not in Verbal IQ, even after controlling for education.

Wisconsin Card Sorting Test performance in above average and superior school children: relationship to intelligence and age.

Above average children outperform average 9- to 14-year-olds on the Wisconsin Card Sorting Test, with intelligence being a significant qualifier of age trends.

The mean IQ of Americans: Massive gains 1932 to 1978.

The mean IQ of Americans increased by 13.8 points from 1932 to 1978, with higher norms being established in each sample, posing a serious problem for causal explanation.

A longitudinal study of sex differences in intelligence at ages 7, 11 and 16 years

At age 16, boys have an IQ advantage of 1.8 IQ points over girls, supporting Lynn's hypothesis that males develop higher average intelligence than females.

Preliminary Real-World Evidence That Average Human Intelligence Really is Rising

The young have increasingly dominated chess since the 1970s, suggesting that population intelligence may be rising.

Childhood IQ's as Predictors of Adult Educational and Occupational Status

Childhood IQ's can predict adult education and occupational status, but not long-term predictions for individual normal children.

Age and intelligence of a group of juvenile delinquents

Boys aged 14 and over have a slightly higher mean IQ than those below 14 years, but no significant differences were found between sexes.

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