Psychology and Finger Length

There was a lot of interesting stuff going on at the Human Behavior and Evolution Society (HBES) conference held recently at California State University, Fullerton (USA).

You can check out HBES.com and read the abstracts of the papers presented. It gives you a real flavor for the kind of "science" being done in the name of evolutionary psychology.

There was a session on "Digit Ratio." Apparently this is a new field of research in evolutionary psychology. It attempts to correlate the lengths of your fingers with various behaviors. The most relevant parameter appears to be the ratio of the length of your index finger and your ring finger (2D:4D). In women these two fingers are the same length while in men the fourth finger tends to be slightly longer.

Two of the papers at the HBES meeting were from Gad Saad, an Associate Professor of Marketing at the John Molson School of Business at Concordia University in Montreal, Quebec, Canada. He's the author of a book called The Evolutionary Bases of Consumption.

Gad Saad recently posted on the Psychology Today blog [Can the Length of Your Fingers Affect Your Consumption?]. He said ...

Some have argued that the 2D:4D is nothing more than a "sophisticated" form of palmistry. Others have ventured that it belongs with astrology and phrenology, former scientific fields that are now completely discredited. The reality is that the sheer number of papers that have yielded robust 2D:4D effects in prestigious peer-reviewed scientific journals suggests that it is going to take more than a flippant dismissal, as the means of critiquing this thriving research stream.

That's an interesting argument. It doesn't address the real issue; namely, whether those papers are scientifically valid or not. It merely states that because they are reviewed and accepted by other evolutionary psychologists they must be true. This is, unfortunately, becoming a common excuse these days.

What if peer review is failing to distinguish good science from bad science? I think this is what's happening in most disciplines these days.

Here's the abstract of the presentation given by Gad Saad's group at the HBES meeting.

Finger length ratio and attitudes towards several product categories
Marcelo Vinhal Nepomuceno, Gad Saad, Eric Stenstrom, Zack Mendenhall

The second-to-fourth finger length ratio (2D:4D), a sexually dimorphic trait, is affected by androgen exposure in utero. It has been linked to a wide range of human phenomena including economic outcomes, personality, sexuality, athletic and musical abilities, health status, and occupational interests to name but a few examples. Surprisingly, it has yet to be investigated in the consumption context. Using a sample of 555 university students, we examined if finger length ratio was negatively correlated with products with a male penchant and positively correlated with products preferred by females. Participants responded to several items, which assessed their attitude towards several product categories namely: cosmetics, electronics, pornography, clothing, movies genres (drama, action, science fiction, romance, animation and war), sports (hockey, boxing, synchronized swimming and gymnastics) and genres of video-games (First-person Shooter, Real-time Strategy, Party-game, Platformer and Life Simulator). Two key findings were obtained. First, the length of the index finger relative to the sum of the lengths of all four fingers (2rel) was generally a better predictor of product attitudes than 2D:4D, given that it yielded a greater number of significant effects. Second, we found significant (p<.05) or marginally significant (p<.10) correlations, in the predicted directions, between 2rel and attitudes towards four out of the nine product categories preferred by males and towards five out of the ten product categories preferred by females. The remaining product categories were not significantly correlated to 2rel. This constitutes the first study to demonstrate a link between a morphological trait and attitudes toward specific products.

Could this be scientific evidence that palm reading actually works?

Does this have anything to do with evolution or is the evolution of consumption a separate study?

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