Academics have thrown doubt on the conclusions of seminal research that linked preschool children’s self-control to their academic achievement and behaviour in later life.

In the 1960s and 1970s, Stanford University psychologist Walter Mischel examined delayed gratification in preschool children.

He gave them a treat such as a marshmallow, but told them they would receive a bigger treat if they delayed eating it for a short period of time.

Follow up research in 1990 showed that those children who had been able to exercise self-control and wait for the bigger reward had better exam results and socioemotional behaviour when they were teenagers.

The findings led to parents being encouraged to raise their children to exhibit self-control, in the hope of benefits later in life.

However, new research, published in Psychological Science, suggests the benefits of delayed gratification are much smaller than originally suggested.

Researchers Tyler Watts, Greg Duncan and Haonan Quan found that the correlation between waiting for a larger treat at the age of 4, and academic achievement when they were 15, was only half that found in the 1990 study.

And they said that the correlation was reduced by two-thirds when they controlled for family background, early cognitive ability, and a child’s home environment.

They added: “Associations between delay time and measures of behavioral outcomes at age 15 were much smaller and rarely statistically significant.”