A new study of identical twins suggests that early reading skills are an indicator of higher intellectual abilities later in life. The study, published in the July 24 journal Child Development, was conducted by researchers at the University of Edinburgh and King’s College London.
Led by Stuart J. Ritchie, a research fellow in psychology at the University of Edinburgh, the research team followed 1,890 identical twins who were a part of the Twins Early Development Study. Participants in the study were representative of the population as a whole.
Twins were used because they are genetically identical. In this study, the twins were also brought up in the same family environments, which allowed the researchers to determine any outside experiences not shared by the twins. Types of non-shared experiences might include having a particularly inspiring teacher or having a group of friends who encouraged reading as a pastime.
According to a journal news release, the research team examined scores from reading and intelligence tests taken when the twins were 7, 9, 10, 12 and 16 years of age. The children took standard IQ tests to measure their general intelligence, and pattern-completion reasoning puzzles to determine their non-verbal IQ.
The investigators found that earlier differences in reading skills between twins were linked to later differences in intelligence. Specifically, they found that the differences in reading that were linked to higher intelligence score in later life were present by age 7. The findings also showed that reading ability was not only associated with higher vocabulary skills and general knowledge, but with improved non-verbal intelligence as well.
“It’s not surprising that being better at reading might improve your vocabulary,” Ritchie told Medical News Today, “but it is surprising that there were effects on non-verbal intelligence.”
“It’s possible,” suggested Ritchie, “that reading helps train children to use abstract thinking, as they have to imagine other people, places and things while reading. This would be helpful in more general problem-solving tasks, such as those on IQ tests.”
Ritchie and his colleagues noted that since the youngest children in their study were 7 years of age, further investigation should be done to identify the precise age which reading starts to affect cognitive development.
“Since reading is an ability that can be improved, our findings have implications for reading instruction,” Ritchie said in the news release. “Early remediation of reading problems might aid not only in the growth of literacy, but also more general cognitive abilities that are of critical importance across the lifespan.”