Research has long shown that students from low-income families tend to lag behind their wealthier peers on standardized test performance and other measures of academic success. Now, a study led by researchers at the Massachusetts Institute of Technology and Harvard finds a correlate to this “income-achievement” gap within kids’ brain structures.
The researchers imaged the brains of 58 lower- and higher-income public school students in seventh and eighth grade and reviewed their scores on the Massachusetts Comprehensive Assessment System exams. They found that the higher-income students had thicker cortex in many areas of the brain, and that some of these differences — including in areas associated with knowledge storage and visual perception — correlated with the students’ MCAS performance. In fact, the researchers believe differences in cortex thickness could explain nearly half of the income-achievement gap found in the study.
“The findings add a biological perspective on what it means to come from a lower socioeconomic background,” says coauthor John Gabrieli, professor of brain and cognitive sciences at MIT and an investigator at the school’s McGovern Institute for Brain Research. He adds that the differences in brain structure are by no means fixed. “We know the brain is highly plastic and can change through motivation and support,” he says.
The lower-income children in the study, published in the journal Psychological Science, received free or reduced-price lunch. Students were eligible for free or reduced-price lunch if their family income was below 185 percent of the poverty line, which roughly translates to less than $42,000 per year for a family of two adults and two children.
Fifty-seven percent of the lower-income students scored proficient or higher on the average of the math and English language arts MCAS tests, compared to 91 percent of the higher-income students.
Other recent research has looked at links between family income and kids’ brain structures. A study published in Nature Neuroscience in March found that the brains of children in families earning less than $25,000 a year had up to 6 percent less surface area than those whose families earned more than $150,000. They also found kids’ scores on tests measuring cognitive skills including reading and memory ability decreased with parental income.
While neither study explored reasons for this difference in brain structure, earlier research has found links between low socioeconomic status and exposure to stress, reduced environmental enrichment, and other factors that influence brain development.
As educators explore ways to shrink the income-achievement gap, programs that improve the quality of education, particularly for low-income students, may help, says Martin West, associate professor of education at the Harvard Graduate School of Education and a coauthor of the Psychological Science paper. He cites charter schools in Boston that combine high expectations of students’ success with longer school days and frequent skill assessment as an example.
Increased opportunities may also lead to differences within the brain, Gabrieli adds.
“People might have the misconception that there can be changes in educational opportunities, but the biology of the brain is fixed,” he says. “We think the opposite — that when there are differences in opportunities, you will see differences in the brain.”