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:



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!

Study in Namibia points out that males & females with a low 2D:4D digit ratio tend to get married at an early age:

The second to fourth digit ratio (2D:4D) is used as a potential marker for prenatal androgen exposure. It is associated with many behavioral and biological variables, including fertility and sexual behavior. However, direct association between 2D:4D and reproductive success—in populations where no contraceptives are used—has not been investigated. Here, we present a study conducted among the semi-nomad Himba population living in northern Namibia. 2D:4D ratios were calculated for a sample of this population (N = 99; 60 women, 39 men), and the results were correlated with age, marital status, age at first marriage, number of children, and number of marriages. As found in the majority of previous studies, males had lower 2D:4D ratios than females. The 2D:4D ratio did not correlate with number of children. Females and males with a more masculine 2D:4D were married earlier and were more likely to have a husband or wife. We suggest that mating preferences for females with masculine 2D:4D are related to masculinity of phenotypic and personality traits of such women, which are beneficial in harsh environmental conditions and/or higher facial masculinity, which influences the perceived age of an individual. At the same time, masculine (physically strong, dominant, and hardworking) males might gather resources necessary to marry their first wife earlier.

NOTICE: 2D:4D digit ratio is known to correlate with many aspects of marriage/relationships, including e.g. the age of the partner, the number of partners, the offspring & the wearing of wedding rings.

On october 9 (2012) Manning et.al. presented the very first 2D:4D digit ratio study in Klinefelter syndrome (XXY).

The results describe how Klinefelter syndrome is typically featured with a high 2D:4D digit ratio + short fingers.

SUMMARY:

The ratio of second to fourth digit length (2D:4D) is a correlate of prenatal testosterone. High 2D:4D is associated with low prenatal testosterone, and reduced sensitivity to testosterone. Klinefelter’s syndrome (KS; 47 XXY) affects the endocrine system, such that low testosterone levels are found in KS foetuses, new-borns and adults. To date, there are no published data regarding the pattern of 2D:4D in KS males. Here we consider 2D:4D in KS individuals (n = 51), their relatives (16 fathers and 15 mothers) and an unaffected control sample of 153 men and 153 women. Adult KS individuals were taller than their fathers and had shorter fingers than fathers and male controls. Compared with fathers, male controls and mothers, KS males had shorter fingers relative to height. With regard to 2D:4D, KS individuals had higher 2D:4D than fathers (right and left hands), male controls (right and left hands) and mothers (left hands). Among KS males older than 13 years there were 34 individuals currently prescribed testosterone and nine not prescribed. In comparison to the former, the latter individuals had higher right 2D:4D and higher right–left 2D:4D. We conclude that KS males have mean 2D:4D values similar to those found in female population norms. In addition, testosterone supplementation in KS males may be most common for individuals with low right 2D:4D.

Keywords:

  • 2D:4D;
  • azoospermia;
  • digit ratio;
  • Klinefelter’s syndrome;
  • prenatal testosterone;
  • testosterone sensitivity

In the two videos below are taken from a Korean TV program featuring Professor John Manning describing how he is able to ‘predict’ the talents in Korean children.

(Manning is talking about visuospatial skills vs. verbal skills)


Ron Jeremy, adult actor.

 JULY 4, 2011 – Finally… the long waited proof is now available: Korean researchers from the In Ho Choi of Gacheon University Gil Hospital, have pointed out that the popular ‘digit ratio‘ does correlate with penile length!

Finger professor John T. Manning had already pointed out in his second book ‘The Finger Book (2008) that a Greek study in the Naval and Veteran’s Hospital of Athens (2002) had pointed out that the length of the index finger correlates with the length, glans & volume of the penis. Manning commented (in ‘The Finger Book’):

“Spyropoulos and his collegues did not measure the remaining fingers, so we cannot be sure of their relationship to penis length. My guess is that they would have found the ring finger the strongest predictor, and that long ring fingers in relation to index fingers would be associated with longer penises.”

The new Korean study shows that John Manning – the ‘finger professor’ – was right… again!

Psychologist John T. Manning, a.k.a. the 'finger professor'.

The researchers from Korea found that the ratio between the second and fourth digits on men’s right hand correlate to the length of his flaccid and stretched penis. A lower index-to-ring finger length ratio indicates a longer (stretched) penis.

NOTICE: The table below is taken from the scientific article; it e.g. illustrates that likewise results were found for body length and penis length – for the ‘flaccid condition’ the result for body length were slightly higher than for the 2D:4D digit ratio, but in the ‘stretched condition’ finger length ratio was a better predictor for penis length!

The key to this relationship may lie in the womb, a team member added:

“During the fetal period, high concentrations of testosterone lead to high testicular activity, resulting in a lower digit ratio, in the present study, patients with a lower digit ratio tended to have a longer stretched penile length.”

The researchers also added that the length of the stretched and flaccid penis does show “a strong correlation” with an erect penile length.

The Korean report was published on july 4 in the Asian Journal of Andrology, and the scientific article is available at Nature.com.


 THE HANDS OF ADULT STAR RON JEREMY:

How can we understand this correlation between finger lenght and penis length?

Let’s take a look at the hands of one of the biggest ‘stars’ in the adult industry today: Ron Jeremy. Jeremy is today known as the ‘best performing’ male adult star ever, he is e.g. listed in the Guinness Book of World Records for “Most Appearances in Adult Films”, and he is noted for his 9.75-inch (~24.75 cm) penis (self-reported according Wikipedia).

How about his hands? His handprints are display at the entrence of Hustler’s Hollywood,  at the ‘Porn Stars Walk of Fame’ in West Hollywood, California – see the picture below. His 2D:4D digit ratio is estimated at 0.85… which is exceptionally low for a caucasian male!


MORE FAMOUS HANDS AVAILABLE AT:

‘Hands of fame’ – The hands of 93 celebrities & famous people!

Handprints of Ron Jeremy, adult actor.

Amyotrophic lateral sclerosis (abbreviated ALS) is a form of motor neuron disease caused by the degeneration of neurons in the brain. The condition is often called Lou Gehrig’s disease in North America, after the famous New York Yankees baseball player who was diagnosed with the disease in 1939. The disorder is characterized by rapidly progressive weakness, muscle atrophy and fasciculations, spasticity, dysarthria, dysphagia, and respiratory compromise. ALS is a fatal disease with most affected patients dying of respiratory compromise and pneumonia after 2 to 3 years; although occasional individuals have a more indolent course and survive for many years. The cause is usually unknown, but a new Canadian finger length study suggests that the onset of ALS may even be determined before birth!

For patients without a family history of the disease, which includes ~95% of cases, there is no known cause for ALS – though environmental causative factors have been indentified.

Interestingly, earlier this year a new Canadian finger length study suggests that the onset of ALS may partly be established even before birth!

The Canadian researchers report:

“A biomarker that has generated considerable interest is digit ratio, the ratio of the second (index) finger to the fourth (ring) finger, 2D:4D. Men have a longer fourth digit relative to the second digit than do women, and the ratio is lower in boys and men than in girls and women. 1 A reduced 2D:4D ratio is assumed to indicate reduced prenatal androgen exposure or sensitivity and high prenatal testosterone levels.”


PEOPLE WITH A LONGER RING FINGER ARE NOT ‘AT RISK’!

NOTICE: Even if you have a longer ring finger, you are probably NOT 'at risk' for ALS!

 The researchers hasten to explain, however, that this does not mean people with long ring fingers will develop the disease — or even that they are at higher risk for it.

“We have not done a study that shows the risk of subsequently getting ALS in people with long ring fingers,” cautioned lead researcher Ammar Al-Chalabi, a professor of neurology and complex disease genetics and director of King’s MND Care and Research Center at King’s College London.

What the study does find, Al-Chalabi said, is that “people with ALS tend to have more ‘male’ hands in that the ring finger is relatively longer than the index finger – something that is a tendency in men.”

“We already know that ALS is commoner in men, but this might suggest that the reason is something to do with the balance of hormones we are exposed to in the womb, because finger length seems to be determined in part by the amount of male hormone a developing baby is exposed to,” he added.

Length of ring fingers & correlates with sexual attraction.

Various studies have shown that babies exposed to higher levels of testosterone when developing in the uterus have longer ring fingers as adults, and higher levels of oestrogen typically result in longer pointer fingers. However, testosterone & oestrogen levels also affect the rest of the body, including a person’s physical appearance. The ratio between the length of the index and ring fingers has been found to be a good indication for a variety of social and economic factors, thought to be directly or indirectly related to the effects of the prenatal testosterone. These photographs are part of a study on beauty and sexual attraction.

In 2010 a Meta-analysis studyby researchers from the University of Ontario, Penn State, and the Centre for Addiction and Mental Health found that the second to fourth finger length ratio (2D:4D) serves as an indicator of sexual orientation. The study included 1.618 heterosexual men, 1.693 heterosexual women, 1.503 gay men, and 1.014 lesbians.

In addition to identifying the normative heterosexual sex difference in 2D:4D for both hands, the researchers found that heterosexual women had higher (more feminine) left- and right-hand 2D:4D than did lesbians. However… the researchers found NO difference between heterosexual and gay men (though moderator analyses by the researchers suggested that ethnicity explained some between-studies variation in men).


MORE  FINGER & DIGIT RATIO REPORTS ARE AVAILABLE AT:

http://www.handresearch.com/news/hands-in-the-news.htm

Last year British researchers reported new confirmative findings for a link between index finger length (relative to ring finger length) and the risk of developing prostate cancer. Men featured with a longer index finger than ring finger, appear to have a 33% higher chance for not developing prostate cancer.

Often such studies are qualified by non-experts as “nonsense” – initially because of the association with classical palmistry. Usually a main argument of concern is the seize of the studied sample: many ‘2D:4D digit ratio’ studies have been focused relatively small samples, and usually with the statistics were simly not strong enough to be applied to individuals. But those arguments can not be used to the describe the new British study!

The new British research involves a study where the hands of 1,524 prostate cancer patients were examined, which were compared with a control group of 3,044 men.

It can also be noted that Professor John Manning described in his second book ‘The Finger Book‘ with great details the suspected link between the ‘2D:4D digit ratio’ and prostate cancer – a complex theory about of role glutamine chains in the sensitivity of hormone receptors, which in their turn play a role in the activation of testosterone in the body:

…The various forms of the androgen receptor have important consequences for our health and behaviour. For example, African-American men have shorter glutamine chains (high sensitivity to testosterone) than white men. Short glutamine chains are associated with an increased susceptibility to prostate cancer, and this may in part explain why the incidence of prostate cancer is higher in African-Americans than in white Americans. …”

In short, there seems to exist a triangular relationship between: 1) the high percentage of prostate cancer in Americans with African ancestry, 2) the length of the glutamine chains, and 3) the length ratio between index finger and ring finger.

The importance of the new British study can be recognized in the fact the use of preventive screening for prostate cancer – which is anno 2010 usually done through the use of a blood test – is still an object of confusion. Simply because the benefits of the screening devices are still very unclear. Meanwhile it is a fact that prostate cancer is known as the No. 1 cause of death from cancer in men (see picture below).

Therfore finger length assessment can become a new tool in prostate cancer screeing!

The British researchers therefore are speculating about how to add a practical application of their finger length study to the traditional methods of prostate cancer prevention screening!

RELATED SOURCES:
More finger length studies
How to read your own palm!