It is known that childhood experience influences brain development but the only evidence scientists have had for this has usually come from extreme cases such as children who had been abused or suffered trauma. Martha Farah, director of the centre for neuroscience and society at the University of Pennsylvania, who led the latest study, wanted to find out how a normal range of experiences in childhood might influence the development of the brain.

Farah took data from surveys of home life and brain scans of 64 participants carried out over the course of 20 years. Her results, presented on Sunday at the annual meeting of the Society for Neuroscience in New Orleans, showed that cognitive stimulation from parents at the age of four was the key factor in predicting the development of several parts of the cortex – the layer of grey matter on the outside of the brain – 15 years later.