Low 2D:4D Values Are Associated with Video Game Addiction

Abstract

Androgen-dependent signaling regulates the growth of the fingers on the human hand during embryogenesis. A higher androgen load results in lower 2D:4D (second digit to fourth digit) ratio values. Prenatal androgen exposure also impacts brain development. 2D:4D values are usually lower in males and are viewed as a proxy of male brain organization. Here, we quantified video gaming behavior in young males. We found lower mean 2D:4D values in subjects who were classified according to the CSAS-II as having at-risk/addicted behavior (n = 27) compared with individuals with unproblematic video gaming behavior (n = 27). Thus, prenatal androgen exposure and a hyper-male brain organization, as represented by low 2D:4D values, are associated with problematic video gaming behavior. These results may be used to improve the diagnosis, prediction, and prevention of video game addiction.

Full report is available here:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0079539

(This concerns a study from Germany: Funding for this study was provided by intramural grants from the University Hospital of the Friedrich-Alexander-University of Erlangen-Nuremberg and by the Ministry for Science and Culture of Lower Saxony.)

The illustrations provide an impression of the results:

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Earlier this month Peter Hill from Melton claimed that his finger length became a clue for the diagnosis of his prostate cancer – after he read a newspaper article which explained that a man whose index finger is shorter than his ring finger (resulting in a low 2D:4D digit ratio) has a higher risk of developing prostate cancer.

Mr. Hill had been concerned that he might have the disease for some time but it was the article, based on research carried out by the University of Warwick in 2010, which prompted him to push his doctor for a blood test.

Peter Hill said:

“I went to Latham House and told them about my concerns, they carried out a blood test to measure the amount of prostate specific antigen (PSA) in my blood, and it confirmed that I had an extremely dangerous and very high result of 96.”

Mr Hill was immediately referred to Glenfield Hospital and then later Leicester Royal Infirmary for further tests meanwhile his PSA level rose to a worrying 117.

Prostate cancer was confirmed and in October 2012 he started hormone treatment for a year and then spent eight weeks, from January 2013, receiving radiotherapy until his PSA level dropped down to below 1.

Peter Hill said:

“The cancer will never go away but they have it under control now and I am currently in remission. I’m just really glad that I pushed my doctor to get the test done and I want to raise awareness of the importance of getting tested to men of a similar age.”

Dr Julian Barwell, of the Clinical Genetics Department at Leicester Royal Infirmary, said: “Mr Hill has now been given as good a result as you can get, and it’s a fantastic success story that he took the initiative to get checked following research he had looked into himself.”

Source: Modern Hand Reading Forum

Prenatal testosterone exposure, as indicated by relative finger length, may be a marker of increased verbal aggression in adults, new research suggests.

In 2 studies, investigators measured the ratio of length of the second digit/index finger to length of the fourth digit/ring finger (2D:4D) of more than 600 young adult volunteers.

Those who had smaller 2D:4D ratios, which correlates with prenatal exposure to testosterone, reported more verbal aggression behaviors than did the participants with higher ratios. In addition, the male participants showed smaller 2D:4D ratios and higher levels of verbal aggression than their female counterparts.

“These findings are very promising,” lead author Allison Shaw, PhD, assistant professor in the Department of Communication at the University at Buffalo–State University of New York, told Medscape Medical News.

The investigators report that this is one of the first studies to use this method to examine prenatal testosterone exposure as a determinant of a communication trait.

Although verbal aggression may be beneficial in certain situations, such as when standing up for oneself if attacked, higher degrees of this behavior have been shown to be detrimental, they note.

“Understanding the causes of verbal aggression, both biological and social, will allow therapists to have a greater understanding of how to work with these individuals,” said Dr. Shaw.

“In terms of clinical practice, I think the take-home message is that there is a longer process that is involved with this. It’s not just a set of behaviors.”

The study is published in the October issue of the Journal of Communications.

Proxy for Sex Hormones

According to the researchers, the ratio of 2D:4D is an indicator of prenatal androgen exposure (PNAE).

“The endocrine literature indicates that the ratio of the length of 2D to 4D is smaller for men than for women and this difference is driven by PNAE,” they write.

“Most importantly, data indicate that 2D:4D is a proxy for sex hormones levels at the time of brain organization.”

Previous research has also shown a link between 2D:4D and mental rotation ability, courtship behaviors, dominance, athletics, memory, and physical aggression.

“I became very interested in understanding how prenatal hormones can affect adult behavior. And as a communications major, I was especially interested in looking at communication behaviors,” said Dr. Shaw.

She noted that a recent study suggested that 2D:4D could predict financial success over a lifetime, which then gave her the idea to apply this technique toward understanding communication behaviors “not just in a social context but also within a biological one as well.”

In the first study, 224 students from the University of Tennessee in Knoxville (52% women; mean age, 20.2 years) had each hand photocopied. From these images, measurements were taken of each finger from its tip to where it meets the palm of the hand.

Questionnaires that included Infante and Wigley’s verbal aggression measure were then administered to all participants.

The second study included 405 students from a large Midwestern university (49.6% women; mean age, 20.4 years). Investigators measured each of the participants’ fingers in person and from images of their hands.

These students filled out the same verbal aggression measure used in the first study as well as the self-reported Infante and Rancer’s Argumentativeness scale and the HEXACO Personality Inventory.

Important Indicators

In the first study, the men’s 2D:4D ratio was significantly smaller than the women’s — but only on the right hand ( P = .005). The men also showed higher levels of verbal aggression than did the women ( P < .001).

In addition, there were statistically significant correlations between 2D:4D and verbal aggression for both hands in both the men and the women.

In the second study, the men had significantly smaller mean 2D:4D ratios than the women on both hands for both the in-person and the photocopied measures. These men were also statistically more verbally aggressive than the women, but they were less argumentative.

Finally, the higher the level of verbal aggression, the lower the 2D:4D ratio for both sexes for the live measure of the right hand and photocopies of both hands.

The ratio did not correlate with either argumentativeness or openness to other experiences.

“This second study showed that 2D:4D didn’t correlate with just any type of communication behavior. Instead, it was with a very specific behavior caused by prenatal testosterone exposure,” said Dr. Shaw.

“Future research would profit by attempting to explicate the mediating mechanisms that result in androgen exposure and differences in 2D:4D and psychological dispositions,” write the investigators.

Dr. Shaw noted that, even so, the difference between the second and fourth digits for everyone “is pretty small.”

“You can’t really look at your hand and know your ratio or know if you’re predisposed to be more verbally aggressive than someone else,” she said.

“Instead, this is a proxy. In human research, we don’t have the ability to measure things perfectly. So these indicators are very important.”

J Commun. 2012;62:778-793. Abstract – The Effect of Prenatal Sex Hormones on the Development of Verbal Aggression

Via: Medscape

Earlier reports about 2D:4D digit ratios and agressesion:

Aggression, testosterone and your finger length!