Finger Length and Personality, Part 3: Q&A

I must admit, I have been smitten with curiosity about the so-called 2D:4D ratio. I find its implications for improved self-awareness and appreciation of diversity to be compelling. This is the third post on the subject, the previous ones having to do with the Higher Perspective article and then my attempt to more accurately measure the 2D:4D ratio. 

I also dedicated a whole edition of L.I.N.K.S. to the subject, and I published a related inquiry on facial symmetry--a feature that, like ring finger length, tends to increase in response to pre-natal androgen exposure. 

That is a lot of exploration and investigation already. But, being the curious sort, I feel one really good question usually inspires two or three dozen more. And so I have prepared for you a list of additional questions (and some preliminary answers). It's my hope that this Q&A monologue will engage readers and inspire something more like a dialog. If you share my interest in this topic and would like to advance the conversation, please feel free to chime in--via comments.

Here we go!

• Does it matter if you measure the ratio on your left hand or your right hand? If the measurements are different, which one is more accurate? 

Higher Perspective said simply to look at the back of your left hand. Most scientific studies I have seen cited have used calipers to accurately measure the digit lengths on the palm side. The copy machine works well enough for practical purposes as any errors are proportional. Some studies specify the right hand for increased accuracy, though I have yet to see why that should be the case. I suspect it's because "most people" are right-hand dominant. I suggest either using the hand with the greatest variation, or, having measured both, averaging the two.

• If your instincts are hardwired, how much choice do you really have in the heat of the moment? Are people with low 2D:4D ratios more likely to be aggressive drivers? 

Studies have shown a positive correlation between longer ring fingers and increased risky behavior. Obviously, behavior can be learned (or unlearned) through training, but it is interesting to note that a certain amount of aggressiveness is apparently innate. Studies have shown, for example, positive correlation between longer ring fingers and aggressive driving. 

• Is there a correlation between finger length ratio and other measures of personality, such as the MBTI profile? Are certain ratios disproportionately represented among Es or Is, for example? 

Low 2D:4D ratios are correlated with increased confidence, risk preference, search persistence, and vigilance. However, these traits are not unique to introverts or extroverts, so there does not appear to be a strong positive correlation between finger length ratios and personality type indicators such as the Jungian Meyers-Briggs Type Indicator (MBTI). It's worth noting that behavior and preference are different. 

• Is there a correlation between finger length ratio and a person's sex (male, female, or intersex), sexual orientation (i.e., gender identity, e.g., male, female, trans, queer), or sexual preference (asexual, heterosexual, bisexual, homosexual)?

The sex difference in digit ratios is unrelated to the Y-chromosome. Estrogen in utero does not produce larger ratios. The presence or absence of testosterone explains all the difference. 

• What are the ranges of ratios that have been measured?

Bailey and Hurd (March 2005) has a sample of 134 people. The distribution of men's finger length ratios has a mean of 0.947 and a standard deviation of 0.029. For women, the statistics are 0.965 and 0.026. 

• Are there any published studies correlating the effects of pre-natal androgens? For example, to what degree are finger length ratios and facial symmetry correlated?

There must be a study correlating finger length ratio and facial symmetry, but I have not found it yet. I did find a study that found a positive correlation between finger length ratio and penile length. Apparently, the researchers took measurements of male subjects while they were under general anesthesia 

• To what extent should finger length ratio influence your choice of  a potential mate? Should the ratio matter more or less than, say, a zodiac sign? In other words, is the finger length ratio merely a persistent but meaningless bit of pop psychology, or is it a window into serious insight?

No, those jeans fit you perfectly! 

• What, if anything, do these topics have in common? How are they related if at all? 
• Numerology
• Tarot
• Astrology (signs of the zodiac)
• Parapsychology (hypnosis, extra-sensory perception, telepathy, etc.)  
• Phrenology (reading the bumps on a person's skull for insights into brain structure and function)
• Chiromancy (reading the proportions of a persons hands and fingers for predictions of future health and well-being)
• Finger Length Ratio
• Positive Psychology
• Myers-Briggs Type Indicator
• Abnormal Psychology

You are looking at a list of 10 topics ranging from parapsychology to pop psychology to main stream psychology. They are listed in order of my estimation of their relative seriousness, beginning with topics that require the most skepticism and progressing to the topics that are relatively more sound. I conclude the Q&A with this point to show that I think the finger length ratio is more useful and more reliable than most of the other topics, but still less accepted in academic circles.

Send or post your responses to the questions posed, your additional questions, more links as you find them, and your own answers as you think of them.