Your hand print can be used as an IQ test

When faced with a mathematical challenge – do you sometimes count things up on your fingers ?

I still do it on occasion, but according to research published in the British Journal of Psychology, fingers are not just a convenient tool used by your brain to keep count, fingers count in how well your brain works too.

This week’s Neurotechnology Tip puts your hand inside a fortune teller’s crystal ball to reveal how your brain is wired.

Weighing up hand prints

The research team gathered the hand prints of 75 seven year olds. But instead of proudly displaying the hand print on the fridge, they carefully measured the length of each child’s fingers. The finger measurements were done with callipers, which meant that the measurement was pretty accurate – the calliper can detect a difference of 0.01 mm.

The researchers were not all that interested in the overall size of the little hands, but in the length of two fingers relative to each other. The fingers of special interest are the index finger, this is the one you typically point with and the ring finger.

The digit ratio for each hand was calculated by dividing the length of the index finger, by the that of the ring finger.

Hand prints are a print out of the brain

The hand print from each child was matched to the score that was attained when the child completed a Standardised Assessment Test (SAT).

Amazingly, the digit ratio was able to “predict” how well they performed on the Standardised Assessment Test. Not the actual IQ per se, but whether the kid was good at numbers or good with words .

A longer ring finger created better maths skills at the expense of literacy skills. The effect was very clear in males, but in girls, a shorter ring finger signified better literacy.

Palm reading is scientific

Now you might have already had your hand print read by a fortune teller – this is not exactly science.

But it can be…..

Finger length is a “sign” of the hormonal mileau which was happening during development in the womb. The hormones which were helping sprout your fingers , were also sprouting the neuronal connections in your brain.

Thinking fingers

It is believed that

• Testosterone strengthens the wiring in the areas of the brain associated with spatial and mathematical skills.
• Estrogen is involved in wiring the areas of the brain associated with verbal ability.

In theory, the ring finger and index finger should be about the same length if things are in balance.

But when there is “extra” testosterone floating about, it encourages the ring finger to sprout, leaving it a little longer than the index finger.

Not a boy thing but a Mom thing

Of course, testosterone is the “boy” hormone , so boys should have more of this hormone circulating. So does that mean boys are wired to do maths and girls are doomed to be mathematically illiterate ?

Definitely not, the evidence suggests the testosterone that counts during development doesn’t come from the developing baby, it is coming from Mom.

Long ring fingers in boys happen when there is “extra” testosterone. Short ring fingers in girls happen when there is a short fall of testosterone.

Do the digit ratio test ?

So grab a pen and a blank piece of paper and carefully trace around your hand, then fish out that ruler and measure the length of your index and ring finger for a little insight into how your brain is wired.

Is your digit ratio accurate ?

PS. If you’re destined to be a mathematical whizz, congrats – you’re THE MAN but be warned, the extra testosterone you experienced during development means you’re at a slightly higher risk for prostate cancer.

Finger length helps predict SAT exam results, study shows - press release from the  University of Bath

To wire up your brain a little each week ………………..

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Further reading

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