How to do the test
For this you will need a friend and a piece of paper.
- Cover your friend's hand with the paper so you can see it but they can't.
- Your task is to gently tap one of their fingernails and their task is to name which finger you have touched (ring finger, little finger, etc.) without moving their fingers to figure it out.
- Repeat this a few times for different fingers, and then swap over so they test you.
What does it tell you?
This test tells you how good you are at recognising which of your fingers is which, obviously, but in children it is also a pretty good predictor of basic maths abilities like addition (Fayol, Barouillet, & Marinthe, 1998).
There are a number of possible explanations for this, including the possibility that the parts of the brain used for sensing and moving the fingers are re-used for carrying out maths tasks, and/or that we typically use our fingers a lot while we are learning to count.
Don't worry if you didn't do well on this task - Gracia-Bafalluy and Noël (2008) have shown that it's possible to train better finger knowledge through games like tracing maze paths with different fingers, and this training has an impact on maths ability!
- Fayol, M., Barrouillet, P., & Marinthe, C. (1998). Predicting arithmetical achievement from neuro-psychological performance: A longitudinal study. Cognition, 68(2), B63-B70.
- Gracia-Bafalluy, M., & Noël, M. P. (2008). Does finger training increase young children's numerical performance? Cortex, 44(4), 368-375.
- Olympic Park.