Putting cash in the hands of mothers can help shape the brains of their babies, according to a rigorous randomized study in the United States.

Family income has been linked to child development numerous times in the past in observational studies, but this is the first time researchers have found direct experimental evidence of how poverty drives such changes.

The findings come from an ongoing study known as Baby's First Year, which is attempting to assess how poverty reduction can impact the cognitive and emotional growth of very young children.