Growing up in poverty can have long-term negative consequences for children. Now, a study offering unconditional cash to a group of mothers on low-incomes in the US is beginning to discover the precise role of parental income in child development. It is the first randomised trial to look at whether a basic income might affect the way a child’s brain develops in this critical period.

Studies of children born into families with low income have found they tend to have more behavioural problems and are behind their peers when they start school. We know that the first few years of a child’s life are the most influential for their development, and brain development is particularly rapid in early childhood and therefore more likely to be influenced by the environment.

However, it isn’t clear whether income directly causes these outcomes, or whether they are a result of other factors associated with growing up in poverty.

To find out, Kimberly Noble at Columbia University and her colleagues approached women on low incomes who had just given birth at four sites in the US, and asked them if they would take part in a study following their child’s development. Around 1000 women accepted and were randomly assigned to one of two groups. The first group, consisting of 40 per cent of the women, received an unconditional monthly cash gift which added up to $333 per month, and the other group received $20 per month. Both groups will receive the money for the first 40 months of their child’s life.

The first babies in the study were born in May 2018, and the team have been following up every year. Preliminary findings from the first year were presented this week at the virtual Society for Research in Child Development Conference.

“To date, the dots are not connected in a careful scientific way,” one of the study authors Katherine Magnuson at the University of Wisconsin-Madison told the conference. “We still don’t know whether the types of early experiences that poverty creates for children will directly impact their early development and specifically their brain development in any meaningful way.”

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To find out whether the cash gift made a difference to mothers in supporting their child’s development, the team are measuring several things. At each yearly follow up, children will be assessed for measures like sleep quality, developmental milestones, overall health and emotional development. One unique aspect of the study is the use of mobile EEG headsets to monitor the infants’ brain activity in their home environments.

The researchers have only analysed data from the first year, and the findings haven’t been peer-reviewed, so it is too early to draw any conclusions from the results.

Almost $4 million has been given out through the study so far. Some parents consented to the researchers keeping track of their transactions and some spending patterns are emerging. For instance, those in the high-cash group are spending more on books for their children, and spending more time reading together, according to surveys the team conducted. This is potentially good news because reading to infants is known to be good for cognitive development, vocabulary and promoting important bonds between adults and children. The researchers say it also seems like very little money was spent on what they call temptation goods like gambling, alcohol and tobacco.

“To my knowledge a study like this has not been done before,” says Charles Nelson at Harvard Medical School, who was a consultant on the study but isn’t part of the research team. “Cash transfer programmes have been around for many years, particularly in countries like Brazil. But they are not common in the US, certainly not at this scale; and none have used brain-based measures as outcomes.”

Eventually, the findings could help with policy interventions to help children born into poverty, or even to find ways to buffer against the effects of poverty later in life.