Psychologists have many cleaver tests to ascertain personality traits of people. Now, according to a study published in the journal Aggressive Behavior, the shrinks have a new tool in their medical diagnostic kit: a 6-inch ruler.
Leander van der Meij and colleagues at the Department of Psychology in The Netherlands report a finding that seems more rooted in mysticism of the palm reading parlor than in science from a laboratory, but there is good biological evidence to back up their conclusion: Two measurements of a man's hand can predict how aggressive and domineering he will be.
To test yourself, simply measure the length of your pointing finger and your ring finger (the second and fourth digit). Measure from the crease where these fingers join the palm to the finger tips. Now divide your pointing finger length by your ring finger length to calculate the 2D:4D ratio. The ratio ranges from about 0.9 to 1.03. The lower the ratio, the higher your aggressive dominance.
Palm reading to measure personality? How can that be?
Here's a clue. The study involved only men: 84 university students between the ages of 18 and 29, who were given psychological tests for aggressive dominance and then had their fingers measured. That's because women have a higher 2D:4D ratio than men; that is, in men the ring finger tends to be significantly longer than the pointing finger, but in women these two fingers are closer to the same length. Lesbians, however, have a more "masculine" 2D:4D ratio, according to a 2010 study by Grimbos and colleagues. Another clue is that girls who share the womb with a twin brother are more prone to aggressive behavior than girls who have a twin sister, according to Cohen-Bendahan in a 2005 study. Even in the animal world aggressive dominance in monkeys is related to a more masculine 2D:4D ratio.