How to put your finger on maths

The results of numeracy and literacy tests for seven-year-old children can be predicted by measuring the length of their fingers, shows new research.In a study to be published in the British Journal of Psychology, scientists compared the finger lengths of 75 children with their Standardised Assessment Test (SAT) scores.They found a clear link between a child’s performance in numeracy and literacy tests and the relative lengths of their index (pointing) and ring fingers.Scientists believe that the link is caused by different levels of the hormones testosterone and oestrogen in the womb – and the effect they have on both brain development and finger length.The researchers made photocopies of the palm of the children’s hands and then measured the length of their index finger and ring finger on both hands using callipers, accurate to 0.01mm.They then divided the length of the index finger by that of the ring finger – to calculate the child’s digit ratio.When they compared this ratio to the children’s SAT scores, they found that a smaller ratio (i.e. a longer ring finger and therefore greater prenatal exposure to testosterone) meant a larger difference between ability in maths and literacy, favouring numeracy relative to literacy.