Adolescents from lower-income backgrounds show a different brain response during classic tests of working memory

Adolescents from higher-income families and lower-income families were asked to do working memory tests while having an MRI scan (magnetic resonance imaging). On average, those from higher-income families performed better on the memory tests. As the working memory task got more difficult, they showed greater activation in parts of the brain that are important for working memory (the front-parietal executive network). They then performed better on a state-wide math test.

Other research has shown that children from poorer backgrounds perform worse on many measures of cognitive ability, including working memory capacity, which determines how much goal-relevant information can be held and manipulated in mind. Children from these backgrounds also perform less well in tests of academic achievement, a pattern known as the income-achievement gap.

Working memory capacity is believed to be a major determinant of both cognitive performance and educational outcomes. Greater capacity is associated with better reading comprehension, problem solving, inhibitory control and performance on math tests.

Previous research has shown that people from poorer backgrounds have less grey matter in the brain and that children who score lower on tests have thinner cortexes. But these physical observations merely indicate the likelihood of different brain functioning and tell us little about how adolescents from different backgrounds might be using their brains differently.

Researchers led by Dr Amy Finn at the University of Toronto in Canada set out to see if different patterns of brain functions could be observed among 67 11- and 12-year-olds from higher- and lower-income backgrounds. The marker of poorer socio-economic background was whether the young person received free or reduced-price school meals. The young people performed a memory test during the MRI scan. After the scan, they completed a nonverbal intelligence test and a second working memory test.

The research raised some new conundrums. For example, some lower-income children who did as well on the memory tests as higher-income children showed less brain activation when the task was hard. How can this be? Are other parts of the brain at work that we are not observing?

But the key finding remained clear. There is a statistically significant link between income status and math test scores that is mediated by working memory performance and the brain activity that occurs during working memory tests.