As a research scientist, Dr. Erina Lee is responsible for the international relationships research at eHarmony. In the following article she described how to use hands in building relationships!

 

 

Whether they’re soft and manicured, strong and calloused, weathered and wrinkled—hands come in all shapes and sizes and can often say a lot about you. They can reveal the tattered fingernails of nervous nail biter, the orange fingers of a cheese puff lover, or the worn hands of a grandmother. And when you look even closer at the many lines and wrinkles, is it possible that your hands can reveal even more? Some people believe that clues to our basic selves can be found in the details of our hands. But do our hands really tell us anything of importance about who we really are? Is it possible that the numerous bumps and ridges unique to every hand hold some insight into our level of intelligence or into our love lives?

In an eternal quest for self-discovery, people have looked towards hand readers, among other mystics, to see if the lines in their hands really tell them something meaningful about themselves and their future. In current times, people turn to internet quizzes and online hand reading to make sense of the heart and life lines and the shape of their hands. Although these tests and quizes can be fun, when put to the test of empirical science, most of these claims and predictions cannot be verified. Furthermore, these uncorroborated predictions about personality traits and future events leave palm reading in the category of a pseudoscience.

Despite the inaccuracy of palmistry readings, however, there are aspects of the hands that have been studied empirically, including finger length. When looking at the palm of your hand, fingers straight together, you will likely notice a difference between your second (index) and fourth (ring) fingers. On average women have longer index fingers, compared to ring fingers while men have longer ring fingers compared to index fingers. This association between the two fingers, called the 2D:4D ratio, is related to levels of androgen exposure (a sex hormone higher in men) in the womb. That means that the amount of male hormones a fetus is exposed to determines this very specific detail of finger length in the hands. The precise mechanism by which androgen works is not entirely clear, but in general most theorists believe that increasing androgen exposure will masculinize a fetus. There is also some evidence suggesting that either too much or too little androgen can be feminizing to the fetus.

Because androgen exposure is related to sexual development and masculinization, researchers have begun to wonder if the 2D:4D ratio, as a marker of hormone exposure, may also predict other characteristics. Hormone exposure has been linked to things like general physical health, cognitive abilities, personality, job preferences, attractiveness, and sexual orientation. While the 2D:4D ratio may relate to these developmental characteristics, thus far the evidence supporting such a link is at best described as mixed. For example, there has been much attention dedicated to whether the 2D:4D ratio relates to sexual orientation. While there have been several studies in this area, some have shown no differences between heterosexual and homosexual men in their 2D:4D ratios (e.g., Williams et al., 2000), and others, like Lippa, have shown heterosexual men having lower 2D:4D ratios compared to homosexual men. Similarly with other characteristics like personality and attraction, the research findings have been fairly inconsistent.

Another aspect of the hands that have been conclusively studied are the ridges, the ones that cover the palms and fingers, the ones that make up our unique fingerprints. The study of these ridges is called dermatoglyphics. Similar to the finger length, these ridges are known to be established earlier in the embryonic development, while the fetus is still in the womb. Researchers have shown dermatoglyphic differences between non-deficient people and those with cognitive or genetic abnormalities, like schizophrenia, Down’s syndrome, and intellectual disability. For example, individuals diagnosed with schizophrenia show fewer ridges between two specific points under the second and third fingers [a-b ridge count] compared to non-schizophrenic controls (Bramon et al., 2005). These findings support the idea that changes in the prenatal environment can display its effects in multiple ways, including changes in cognitive development and ridges of the hands. However, the findings do not assume that all people with fewer ridges have cognitive deficiencies.

To summarize, we do know that specific details in our hands are affected by early hormonal exposure and other environmental influences in the womb. And we know that this early exposure also affects other aspects of our development. While it is intriguing to speculate further that details in our hands can predict aspects of our personality or behavior, these conjectures have not been empirically supported. It’s also likely that there are more direct measures of personality, intelligence, and behavioral traits rather than the hands. But even though you can’t currently rely on your hands to unlock all of your mysteries, one thing you can count on is more studies and discussion about them to come.

A male hand + a female hand.

Hand shape varies between the two sexes: males typically have larger, relatively broader hands, while females typically have smaller, relatively narrower hands. But hand shape also varies among the various populations around the world: in Asia the avarage hand shape is relatively narrower than in European & North American countries. And there is even a link between hand shape & intelligence!

But in order to understand these patterns properly, one first has to understand the relations ship between hand shape & body length. Because in general, all longer populations in the world (males, Europeans & North Americans) typically display a relatively broad hand shape, while all small populations (females, Asians) typically display a relatively narrow hand shape.


-
HAND INDEX:

A good measure to describe the shape of the hand is the so-called ‘hand index’, which is defined as the ratio between the ‘hand width’ (= palm width measured at the metacapals) vs. the ‘hand length’ (= the distance between the tip of the middle finger and the distal wrist crease).

The average ‘hand index’ in human kind is close to 0.44, and is typically much higher than the ‘hand index’ seen in primates, which is typically (far) below 0.40 (though in gorillas – the largest of all primate species – the ‘hand index’ is higher than 0.40).

NOTICE: Finger length can also be measured relative to ‘hand length’ & ‘hand width’, but that topic will be discussed later.



-


HAND SHAPE & SEXE:

In males the ‘hand index’ is typically higher than 0.44, and measures above 0.45 are often seen. While in females the ‘hand index’ is typically lower than 0.44, and measures below 0.43 are not rare at all. These sexe differences are for a large part the result of the body height differences between males and females.


HAND SHAPE & RACE:

The average ‘hand index’ among the various races differs significantly, and is typically lower among asians. In people from China does not vary a lot from the average of human kind, but among for example people from Japan & India the ‘hand index’ is typically close to 0.43 or even lower. At least partly these differences are explained by racial differences in body height.


HAND SHAPE & IQ:

A high hand index typically correlates with a low IQ. And this link between hand shape & IQ has been confirmed in quite a few studies among various types of populations.

In a 1980 study in the former Yugoslavia reported among 540 men a negative correlation between hand index & all 10 measures for IQ.

And the two most common causes for mental retardation (Down syndrome & fragile-X syndrome) are known for having typically a relatively broad hand (= high hand index).

Regarding the sexe differences, one has to be aware of the earlier mentioned point that tall populations typically have a higher ‘hand index’. The fact that women have a lower ‘hand index’ compared to men, is largely neutralized by the fact that women are smaller than men. And therefore there one should not associate this sexe difference with IQ differences among the sexes (because so far there is no evidence for that at all).

And finally there is evidence that when the ‘hand index’ is corrected for body height, then this appears to explain a significant part of the IQ differences that are typically seen between the nations of the world. Though this issue has not been studied thoroughly.


HIGH OR LOW ‘HAND INDEX’ IN INDIVUALS:

The above describes patterns for hand shape implicate that regarding the implications of a high or low ‘hand index’ indivuals, one always has to consider sexe & race before jumping into conclusions!

Time for a hand shape palm reading… what is your ‘hand index’?

This is how to measure the dermatoglyphic AtD-angle

Most people are aware that they have fingerprints. But few people are aware of the likewise dermatoglyphic features in their palms. One of the most interesting characteristics of the palmar dermatoglyphics concerns the so-called AtD-angle: which concerns the angle between the a- triradius (under the index finger), the axial triradius (near the wrist), and the d-triradius (under the pinky finger).

The AtD-angle is e.g. known for it’s significance in Down syndrome (trisomy 21): most people who have Down syndrome have an AtD angle > 57o (80%), while in healthy people this characteristic is far less common (7%). But quite a few other trisomy syndromes are featured: see the picture below.
Interestingly, beyond the trisomy studies, a few other studies have indicated that the AtD-angle provides a significant clue about intelligence.

A 2010 STUDY:

Exactly one year ago a study from India reports:
 
Significant difference in the total t’ angle of the left palm was observed between mentally retarded patients and control group.Atd angle varied form 30o to 65o in normal individuals, where as in case of mental retardation < 30o to > 65o angle variationwas observed.

A 1980 STUDY:

And the significance of a small AtD-angle as a marker for high intelligence was e.g. confirmed in a 1980 study from Zagreb (former Yugoslavia), which reports:
 
“The atd angle and FRC1 of both hands in males and females are the main discriminators for classification results of canonical discriminant analysis, for more than 80% of the tested persons.”
IS AtD-ANGLE A RELIABLE MARKER FOR IQ?
 
While the AtD-angle is included in the Dermatoglyphic Multiple Intelligence Test (DMIT), the mentioned studies clearly indicate that in isolation the AtD-angle can not be used as a reliable marker for IQ – simply because the AtD-angle highly varies among the individuals of various IQ populations.
 
At a later stage (hopefully in 2011) a new palmar dermatoglyphic marker will be introduced – based on the ‘configuration shape’ of four palmar triradii. Early results indicate that this new marker represents a more reliable marker for Down syndrome (compared to the AtD-angle) … and when combined with the major palmar lines it appears to provide a significant clue for IQ!
 
 
The picture below provides an overview of the major dermatoglyphic markers in the palm and fingers.

Just another concept of how various types IQ could relate to the fingers...?

The previous post introduced Dermatoglyphics Multiple Intelligence Test (DMIT) – which e.g. describes how various aspects of intelligence could relate to the 10 individual fingers & the brain lobes. Unfortunately there appears to be no (academic) scientific evidence available which confirms the validity of the DMIT-model. But there appears to be multiple evidence available which does confirm that various hand features do provide clues to the general intelligence – specified to the intelligence quotient (IQ)!

In the next 3 posts a quick introduction to how various hand dimensions correlate with IQ, starting with: hand shape.

 • HAND SHAPE & IQ:

The two most common causes of a mental retardation (Down syndrome + fragile X-sydrome) are typically featured with relatively broad palm. This typically results in a high ‘hand index': > 47. 

NOTICE: The ‘hand index’ is defined as: 100 x the quotient of the palm width and the hand length. A ‘hand index’ of 0.47 or higher could be described as high, because far most international ‘hand index’ studies so far indicate that the average varies from 42 to 0.46 (Japanese males: 43.1, American males: 46; Japanese females: 42.3, American females: 43.7). 

So, one could expect that a low ‘hand index’ could provide a clue to a high IQ. But one should be very aware of the fact that the ‘hand index’ varies among men (higher) and women (lower), and among ethnic populations (lower in asians, higher in caucasians).

Interestingly… a 1980 Zagreb study on a large sample of males (N=540) has pointed out that ‘hand width’ does correlate negative with IQ (confirmed at all 10 IQ measures involved in the study). The study also reported that ‘hand length’ did not correlate with IQ – some of the dimensions produced very small positive correlations, which raises the question whether ‘hand index’ would have produced more signficant results than ‘hand width’.

NOTICE: The 1980 study also reveal that all 10 IQ measures produced positive correlations which ‘body height’ – a result which has been confirmed by many studies.

The picture below demonstrates how to measure ‘hand width': in scientific studies this is always done at the position of the metacarpals (0ne could use the starting point of the life line as an easy identifyable point of reference).

And hand length is measure from the distal wrist crease to the tip of the middle finger. 

In 1983 American developmental psychologist Dr. Howard Gardner argued that the concept of intelligence as traditionally defined in psychometrics (IQ tests) does not sufficiently describe the wide variety of cognitive abilities humans display. His theory became know under the name ‘Multiple Intelligence’ (MI). A few years ago a rather remarkable commercial spin-off from Gardner’s theory became available: a product named the DMIT, which stands for: ‘Dermatoglyphics Multiple Intelligence Test’.

The origins of the DMIT test were developed in Taiwan,  and became available in various Asian countries as a franchise product. The product claims to be a scientific product focussed on assessing the ‘multiple intelligences’ of young children. Basically, the product suggests that one can assess Gardner’s multiple intelligences via the 10 fingerprints of your hand. And the assumption is made that each finger is connected with the 5 brain lobes of the hemispheres (see the picture below).

Is the DMIT a valid test?

So far there appears to be no public research available to answer this question – though an intelligent reader could recognize from this point solely a clue about the nature of this so-called ‘scientific test’. 

By the way, Gardner’s theory describes only eight basic types of intelligence to date – though without claiming that this is a complete list. Gardner’s original list included only seven of these, but in 1999 he added a naturalist intelligence. He has also considered existential intelligence and moral intelligence, but does not find sufficient evidence for these based upon his articulated criteria.

Howard Garnder’s ‘multiple intelligences':

More detailed considerations + links to GeneCode & ThumbRule DMIT websites are available at the Modern Hand Reading Forum:

IQ TEST: Does your intelligence correlate with your fingerprints & dermatoglyphics?

A 'family tree' of the major major lines.

In 2004 Chinese researchers present a new approach to study the hand lines for biometric purposes. They applied a mathematical model on hand prints and were able to identify six types of  palmar crease variations – based on the core characteristics of the three ‘major palmar lines’. Recently, in line with the Chinese research a new more advanced (PIC) model was introduced which e.g. describes 21 types of major hand line variations which are displayed in ‘a family tree of the major hand line types': see the picture above.

Interestingly, the new study reports e.g. about a correlation between the palmar lines and intelligence (IQ): left hand vs. right hand asymmetries appear to be involved, plus a lower prevalence of MPA’s – such as the simian line & Sydney line).

More details are available in the article:
What can formations in hand lines reveal?

For more information about various aspects of the palmar lines the following book is recommended:
‘Anthropology of Crease Morphogenesis’.

NOTICE: The three major palmar lines concern:

- The ‘radial longitudinal crease’, in palmistry a.k.a. the ‘life line';
– The ‘distal transversal crease’, in palmistry a.k.a. the ‘heart line';
– The ‘proximal transveral crease’, in palmistry a.k.a. the ‘head line’.

Related news reports & articles are available at:
News about the palmar creases / hand lines.