Patience and rewards – the ‘raisin test’

This week’s post is about a study carried out at the University of Warwick which has been in the news recently, in which they were able to predict a child’s intelligence as they grew older using a simple test with a raisin.

In this test, a raisin was covered with a cup, and put in front of the young children who took part. They were told they had to wait for a minute until they could eat the raisin.

Results showed that children who were born prematurely were more likely to eat the raisin without waiting for the minute to elapse, and that the children who were more impatient did not perform as well in school when they were older – aged 8 (Wolke et al).

This method tests for something called ‘inhibitory control’ and is a cognitive skill learnt during childhood and is linked to activity in the prefrontal cortex. It is often disrupted in children with ADHD.

It is a similar method to the well known ‘Stanford Marshmallow Test’, in which children were told they could eat one marshmallow now, or wait for 15 minutes and have two. This research was carried out by Walter Mischel, who followed up on his original study to see how successful the original participants were during adulthood. This also found a correlation between those who were able to wait for the reward, and future successes.


Mischel believed that some children were able to wait for the larger reward because they were capable of more abstract thinking, and could picture the reward occurring. The fact that executive function performance during childhood can predict later achievements is fascinating, although of course it is not the only factor.

So, would you like one marshmallow now?

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