Despite that most people can best be described as 'ambiverts', the dimension Extraversion-Introversion is generally considered as a key-dimension of human personality. The terms 'extraversion' and 'introversion' were first popularized by Carl Jung (1913) and became later included in many personality theories; today some speak even about the so-called 'extravert ideal' (a term recently introduced in 2012 by American author Susan Cain). This article presents a first (solid) attempt to describe how the dimension Extraversion / Introversion can be recognized via a (multi-perspective) study of the hand.

The results are based on a hand study in 48 Dutch people: 27 extraverts + 21 introverts (including: 34 females & 14 males) - who were selected by age (19-54), ethnicity (white), IQ (above average) and high/low scores on the Extraversion dimension of the Dutch version of the NEO PI-R personality questionnaire. All hand materials were collected in 1997/1998.

6 Hand signs have been identified featured with strong, consistent results for both the male- and female group.
A schematic visual summary is presented at the BOTTOM of this page.


CONTENT OVERVIEW:

• Extraversion & the Big Five model
• Extraversion defined by detail: 6 facets [according NEO PI-R]
• Extraversion fluctuates around the world
• Extraversion in the hand reading literature!
• RESEARCH RESULTS: 6 Hand signs for Extraversion & Introversion!

Extraversion & the Big Five model
Over time Various independent researchers concluded that human personality can best be descrived using five broad factors. This explains why in time the Big Five framework presented by Costa & McCrae (1992) became recognized as representing the standard in academic psychology.

The Big Five factors are:

Extraversion - Neuroticism - Openness - Agreeableness - Conscientiousness



Wondering about your Big Five personality profile? There are various credible online Big Five online tests available; the picture below presents 2 Big Five profiles resulting from the BBC Big Five test

(NOTICE: 'low' scores for Extroversion can be associated with Introversion; 'medium' scores with Ambiversion; and 'high' scores with Extraversion).



Extraversion defined by detail: 6 facets [according NEO PI-R]
Though the verb 'extraversion' has become an element in the daily lives of many people, but sometimes it appears as if individual tend to atribute different meaning to the word. This is probably because the word kind of has various meanings in different contexts.

The terms introversion and extraversion were first popularized by Carl Jung (after Freud had adopted the word in his 'libido' psychology), although both the popular understanding and psychological usage differ from his original intent.

The trait of extraversion-introversion is now known as a central dimension of human personality theories:

Extraversion tends to be manifested in outgoing, talkative, energetic behavior, whereas introversion is manifested in more reserved, quiet, shy behavior. Virtually all comprehensive models of personality have adopted these concepts in various forms - examples are: the Big Five model, Jung's analytical psychology, Hans Eysenck's three-factor model, Raymond Cattell's 16 personality factors, the Minnesota Multiphasic Personality Inventory, and the Myers Briggs Type Indicator.

The picture below presents an overview of six facets of Extraversion according the Big Five model (the NEO PI-R questionnaire is measuring each facet through 8 multiple-choice questions).




NOTICE: "Although many people view being introverted or extroverted as a question with only two possible answers, most contemporary trait theories measure levels of extraversion-introversion as part of a single, continuous dimension of personality, with some scores near one end, and others near the half-way mark.[10] Ambiversion is a term used to describe people who fall more or less directly in the middle and exhibit tendencies of both groups. An ambivert is normally comfortable with groups and enjoys social interaction, but also relishes time alone and away from the crowd." (cited from Wikipedia)




In 2012 Susan Cain's argues in her bestseller Quiet: The Power of Introverts in a World That Can't Stop Talking how modern Western culture misunderstands and undervalues the traits and capabilities of introverted people, leading to "a colossal waste of talent, energy, and happiness." Cain defines the introvert-extrovert spectrum in terms of preferences for different levels of stimulation. Her definition for Introversion is: "introverts have a preference for a quiet, more minimally stimulating environment" (see also picture above).


Extraversion fluctuates around the world
Studies around the world have indicated that the distribution of mean Extraversion factor scores fluctuates around the world - see pictures (McCrae, 2004; 23andMe, 2011; MyPersonality, 2008).

The data reveals that people from Europe & US tend to score higher for Extraversion than people from Asia (Allik & McCrae, 2004).





Extraversion in the hand reading literature!
What does the hand reading literature report about extraversion/introversion?

Various authors have presented attempts to define 'extraversion' and/or 'introversion' through a combination of hand characteristics:






Arnold Holtzman:

- 'Applied Hand Reading':

• page 41 - EXTRAVERT: hard hands; INTROVERT: soft hands;
• page 68/69 - EXTRAVERSION: flattened lower part of hypothenar (mount of moon);
• page 69 - INTROVERSION: swelled lower hypothenar (mount of moon) and dropping into the wrist.

- 'Psychodiagnostic Chirology in Analysis and Therapy':

• page 41 - EXTRAVERT: an extrovert formula would be the rule when the life instinct (area just below the point of origin of the upper transverse crease) is the driving influence; INTROVERT: an introvert formula would be the rule when the death instinct (= pronounced plunge of the hypothenar eminence into the wrist) holds sway over an individual's program of survival;
• page 68 - EXTRAVERT: hard hand; INTROVERT: soft hand.






Johnny Fincham:

- 'The Spellbinding Power of Palmistry':

• page 37 - EXTRAVERT: thumb angle: 90 degrees; INTROVERT: thumb angle: 20 degrees or less;
• page 42 - INTROVERT: all fingers leaning to little finger side;
• page 113 - INTROVERT: fragmented girdle of venus;
• page 117 - INTROVERT: very strong sun/apollo line.

- 'Palmistry: From Apprentice to Pro in Twenty-Four Hourse':

• page 197 - INTROVERT: closed fingers tightly together; skin quality: either silk or course; lines: faint and fine or thick and trench-like; head line: curves deeply (downward);
• page 198 - INTROVERT: head line: tied to vitality line; long 2nd finger; EXTRAVERT: 'naturally hold their fingers wide spread'; 4th finger: long; head line: straight; lines: strong and bold; large gap between head line and life line.

(NOTICE: It's rather remarkable that in the perspective of Extraversion/Introversion Fincham appears to talk about completely different hand features in each of his books...???)







Nathaniel Altman:

- 'Sexual Palmistry':

• page 20 - EXTRAVERT: spatulate hands;
• page 67 - INTROVERSION: small, deficient lower mount of mars;
• page 80 - EXTRAVERSION: head line seperate from life line;
• page 132 - EXTRAVERSION: angle between index finger and thumb;
• page 137 - EXTRAVERSION: flexible hands, generous thumb.

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HAND RESEARCH RESULTS:

6 Hand signs for Extraversion & Introversion!
This concerns a study of hand signs in the perspective of the Big Five dimension Extraversion in a Dutch population of 48 subjects (14 female + 7 male introverts scoring 8 or 9 on the Dutch NEO PI-R personality questionnaire; and 20 female + 7 male extraverts scoring 1 or 2).

A 'multi-perspective' exploration of the hands (hand prints) has resulted in the identification of 6 hand signs with strong (consistent) results for both the male- and female groups. A description for the 6 individual hand signs in the 'Hand Model for Extraversion' is presented in table 1.

TABLE 1: Pearson correlations for 6 hand signs.

HAND SIGNS	DESCRIPTION
1 - PL:PB ratio	Palm length (pl) : palm breadth (pb) ratio both dimensions measured with ruler
2 - HypoTh:Th ratio	Hypothenar (HypTh) : thenar (T) ratio both zones assessed for overall development
3 - FL:PB ratio	Finger length (fl) : palm breadth (pb) ratio both dimensions measured with ruler
4 - 2D:4D digit ratio	2D:4D digit ratio both finger lengths measured with ruler
5 - Distal crease term.	Distal crease radial termination upward curved / flatly curved / simian crease
6 - Prox. crease term.	Proximal crease radial termination connected / partial connected / disconnected

Table 2 presents an overview of the Pearson correlation results regarding the Big Five dimension Extraversion (high scorers vs. low scorers) for the 6 individual hand signs.

TABLE 2: Pearson correlations for 6 hand signs.

HAND SIGNS	Males + Females	Males	Females
1 - PL:PB ratio	-0.26*	-0.20	-0.31*
2 - HypoTh:Th ratio	-0.38**	-0.54*	-0.29*
3 - FL:PB ratio	-0.38**	-0.30	-0.49**
4 - 2D:4D digit ratio	-0.19	-0.51*	-0.11
5 - Distal crease term.	-0.36**	-0.59*	-0.29*
6 - Prox. crease term.	-0.27*	-0.10	-0.33*

* p = sign. at 0.05; ** p = sign. at 0.01


Table 3 presents an overview of the distributive results ranked by sexe & the Big Five dimension Extraversion (high scorers vs. low scorers) combined for the 6 individual hand signs. NOTICE: For hand signs 1,2,3 & 4 the values were first transformed into numbers between 0 and 10, and then grouped into the categories: 'low', 'medium' and 'high'.

TABLE 3: Pearson correlations for 6 hand signs.


Table 4 presents an overview of 'independent' regression analysis results, describing all combinations of hand signs (8 hand sign combinations) that have produced highly significant results (requirement: p < 0.001). These combinations represent the best predictors for whether the individuals are HIGH scorers (= extraverts) or LOW scorers (= introverts) on the Big Five dimension Extraversion [according the NEO PI-R personality questionnaire].

TABLE 4: Anova F-ratio (+ weights) for the 8 most significant hand sign combinations [combi I to combi VIII are ranked by p-value]. * p = sign. at 0.05; ** p = sign. at 0.01; *** p = sign. at 0.001


The 'weights' inside the 8 hand sign combinations (for males and females combined) have been used to calculate the overall weight for each of the 6 hand dimensions in the hand-model for Extraversion (the large version is presented at the BOTTOM of this page).

An interesting aspect inside these results is that all combinations with 3 different hand dimensions involved [combinations I, II, III & IV] have produced more significant results compared to the combinations with only 2 different hand dimensions involved [combinations V, VI, VII & VIII]. This can be recognized as evidence for a fundamental principle proposed in 'Multi-Perspective Palm Reading': hand sign combinations tend to become more valuable when these are found in multiple hand dimensions!

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Finally, the 'Hand Model for Extraversion' (see picture at the bottom) describes 6 hand sign variants that are common in the hands of the extraverts (left-side of the picture) + 6 hand characteristics that are common in the hands of the introverts (right-side of the picture). The 'weigths' (behind each hand characteristic - see picture) represent the estimated significance for each hand characteristic in the perspective of the full model.

Table 5 presents results for 'independent' regression analysis based on the full weighted combination of the 6 hand signs together. The results in table 5 suggest that the weighted combination of all 6 hand signs produces (much) better results than any of 8 most significant smaller hand sign combinations described in table 4.

HAND MODEL	Males + Females	Males	Females
1 & 2 & 3 & 4 & 5 & 6 (weights: -0.04, -0.29, -0.25, -0.05, -0.32, -0.04)	17.762***	22.963***	17.762***

A discriminative analysis has pointed out that the 'Hand Model for Extraversion' can identify 85.4% of the subjects (41 out of 48) correctly as a HIGH of LOW scorer. This implicates that 7 out of 48 subjects (= 14.6%) were not correctly assesed by the model (though one of these 7 subjects would have been classified correctly via the use of an alternative criterium).


A few more details have been described in the preceeding articles:
• Extraversion, 2D:4D digit ratio & hand shape!
• Introverts have longer fingers, Extraverts have wider palms


* Despite the fact that the validity & reliability of NEO PI-R personality questionnaire has been confirmed in many studies, one should be aware that the results in an individual may fluctuate during a lifetime for various reasons (possibly due to significant life events and/or other developments).