They claim that differential ring and index finger measurements in adults is an indicator of womb exposure to testosterone. As such, finger length can be used to predict both physical and mental performance in both men and women.
Men usually have a longer ring finger than the index finger. The bigger the difference the more testosterone exposure. Women tend to have just the opposite. Index fingers longer than ring fingers.
After Claudette and I stopped measuring our ring and index fingers, we exchange bemused looks as we verified the researcher's findings.
In one test, a researcher visited a college track & field team of six male runners. He measured finger differentials of each and then predicted the finish order in a race based strictly on the measurements. He got 1st, 2nd and 3rd place correct. Reversed 4th and 5th place finishers and got the 6th correct.
A little Googling on the net, I turned up the following:
"...Exposure to testosterone in the womb is said to promote development of areas of the brain often associated with spatial and mathematical skills, he said. That hormone makes the ring finger longer. Estrogen exposure does the same for areas of the brain associated with verbal ability and tends to lengthen the index finger relative to the ring finger.
To test the link to children's scores on the College Board's Scholastic Assessment Test (for which the name has changed a number of times in the past 100 years), Brosnan and his colleagues made photocopies of children's palms and measured the length of their index and ring fingers using calipers accurate to 0.01 millimeters. They used the finger-length ratios as a proxy for the levels of testosterone and estrogen exposure.
The researchers then looked at boys' and girls' test performances separately and compared them to finger-length ratio measurements. They found a clear link between high prenatal testosterone exposure, indicated by the longer ring finger compared to the index finger, and higher scores on the math SAT.
Similarly, they found higher literacy SAT scores for the girls among those who had lower prenatal testosterone exposure, as indicated by a shorter ring finger compared with the index finger."Not sure if all this is on the up and up, but it's going to be hard not to stare at the hands of the little monsters in class starting September.