Specific cognitive abilities in 5- to 12-year-old twins

Area of Science:

• Developmental Psychology
• Behavioral Genetics
• Cognitive Neuroscience

Background:

• Previous twin studies indicate significant genetic variance for cognitive abilities in adolescents and adults.
• Research on cognitive development in early childhood requires further investigation into genetic and environmental influences.

Purpose of the Study:

• To investigate the genetic and environmental contributions to specific cognitive abilities in young twins.
• To compare findings in young twins with existing data from adolescent and adult twin studies.

Main Methods:

• Administered eleven cognitive ability tests to 108 pairs of young twins (average age 7.6 years).
• Assessed internal consistencies and two-month test-retest reliabilities for all measures.
• Adjusted cognitive scores for age due to high correlations.

Main Results:

• Significant genetic influence was found for only one measure, the Peabody Individual Achievement Test (PIAT) Reading Recognition.
• Possible genetic influences were suggested for vocabulary and Wechsler Intelligence Scale for Children-Revised (WISC-R) mazes.
• Environmental influences, both between-family and within-family, dominated most cognitive measures, especially nonverbal ones.

Conclusions:

• Environmental factors play a dominant role in the development of specific cognitive abilities in young children.
• Findings contrast with previous twin studies suggesting stronger genetic influences in older individuals.
• Early education environments significantly shape cognitive development during childhood.