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An investigation into the relationship between digit length ratio (2D: 4D) and psychopathy

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Abstract

This study investigates whether a higher level of pre-natal testosterone, as indicated by the 2D: 4D digit ratio, is a correlate of psychopathy and cognitive empathy. The main research hypothesis predicts that 2D: 4D digit ratios will correlate negatively with psychopathy scores and positively with cognitive empathy scores. The study facilitates a within-subjects correlational design, using a quasi-experimental method consisting of questionnaires and digit measurements. Fifty-four participants volunteered and were gathered via purposive and convenience sampling. Each participant completed a self-report psychopathy scale, a cognitive empathy test, a verbal IQ test and a scan of both hands. The scans were later measured and computed for digit ratios. T-tests, multiple partial correlations and multiple regression found that, contrary to the research hypothesis, a higher level of pre-natal oestrogen, as indicated by a larger 2D: 4D digit ratio, is a positive correlate of psychopathy in females, and a positive correlate of callous affect (psychopathy sub-scale) in males, at less than 0.01 probability levels. Gender is also a correlate of psychopathy, as males scored significantly higher than females at 0.01 probability levels. This result sheds an interesting new light on the physiological correlates of psychopathy and the role that pre-natal oestrogen plays in organisational effects on the brain during pre- and post-natal development.

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... A number of investigators have also explored a possible association between 2D:4D ratio and criminality. Focusing on college students, an interesting investigation [13] has shown that 2D:4D ratio correlate with psychopathy and callous affect. Investigating incarcerated methamphetamine users, others [14] have found that greater prenatal testosterone exposure, as indicated by 2D:4D ratio, is associated with increases in anger thinking and a reduction in cognitive flexibility, at least among individuals who have experienced physical abuse [14]. ...
... We found that, even when controlling for education and impulsivity, 2D:4D ratio significantly predicted criminality. Thus, our results nicely augment earlier investigations regarding the link between 2D:4D ratio and criminality, such as the association between 2D:4D ratio and psychopathy [12] as well as 2D:4D ratio and anger rumination and cognitive flexibility among incarcerated methamphetamine users [13]. ...
Article
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Personality characteristics, particularly impulsive tendencies, have long been conceived as the primary culprit in delinquent behavior. One crucial question to emerge from this line of work is whether impulsivity has a biological basis. To test this possibility, 44 male offenders and 46 nonoffenders completed the Eysenck Impulsivity Questionnaire, and had their 2D∶4D ratio measured. Offenders exhibited smaller right hand digit ratio measurements compared to non-offenders, but higher impulsivity scores. Both impulsivity and 2D∶4D ratio measurements significantly predicted criminality (offenders vs. nonoffenders). Controlling for education level, the 2D∶4D ratio measurements had remained a significant predictor of criminality, while impulsivity scores no longer predicted criminality significantly. Our data, thus, indicates that impulsivity but not 2D∶4D ratio measurements relate to educational attainment. As offenders varied in their number of previous convictions and the nature of their individual crimes, we also tested for differences in 2D∶4D ratio and impulsivity among offenders. Number of previous convictions did not correlate significantly with the 2D∶4D ratio measurements or impulsivity scores. Our study established a link between a biological marker and impulsivity among offenders (and lack thereof among non-offenders), which emphasise the importance of studying the relationship between biological markers, impulsivity and criminal behavior.
... Nonetheless, some studies have shown associations between low second-to-fourth digit ratio (2D:4D; a proxy for exposure to androgens in utero) and criminality (Hanoch et al., 2012, Hoskin andEllis 2014), traffic violations (Schwerdtfeger et al., 2010) and self-reported criminal behavior (Ellis and Hoskin, 2013). However, other studies have not been able to show this effect (Blanchard and Lyons, 2010;Anderson, 2012). Moreover, the digit ratio is not a direct measurement of exposure to androgens in utero and its reliability has been discussed (Putz et al., 2004). ...
... Thus, the hypothesis that hyperandrogenism in adulthood increase the risk of criminal behavior was partly supported. It has previously been argued that prenatal androgens increase the risk of subsequent criminal behavior (e.g., Ellis and Hoskin, 2013), and even though some evidence supports this hypothesis Hoskin, 2013, Hanoch et al., 2012) not all studies are consistent (Anderson, 2012;Blanchard and Lyons, 2010). The prenatal hypothesis did not get support in our study, as we did not find an increased risk of crime in CAH. ...
... In adults, the association between 2D:4D and antisocial behaviors is scarcely studied. Only one study assessed the association between 2D:4D and psychopathic traits in college students (mean age of 27) measured with the Self-Report Psychopathy Scale (SRP-II) and found that total psychopathy scores were positively correlated with right hand 2D:4D but only in females (r ¼0.45, p o0.05) (Blanchard and Lyons, 2010). In contrast, criminal tendency and antisocial behaviors were strongly and positively correlated with left hand 2D:4D but only in males (r ¼0.71, po0.05) which is a surprising finding. ...
... Also, higher fetal T as indicated by a lower 2D:4D ratio has also been related to lower social cognition in girls between 2 to 5 years , lower cognitive empathy in women aged 20 to 25 (Van Honk et al., 2011a), and lower emotional empathy in women aged 18-49 years (Kempe and Heffernan, 2011). However, these results with regard to 2D:4D have been inconsistent and different studies have found no associations with social cognition in boys aged 2 to 5 , and cognitive empathy in men aged 18 to 49 years (Blanchard and Lyons, 2010;Kempe and Heffernan, 2011). Nonetheless, since amniotic fluid studies have greater construct validity than 2D:4D ratios and consistently find a negative association between fetal T exposure and social sensitivity/empathy in childhood we suggest that a small negative correlation likely exists. ...
Article
Life-course persistent antisocial behavior is 10 to 14 times more prevalent in males and it has been suggested that testosterone levels could account for this gender bias. Preliminary studies with measures of fetal testosterone find inconsistent associations with antisocial behavior, especially studies that use the 2D:4D ratio as a proxy for fetal testosterone. However, circulating testosterone consistently shows positive associations with antisocial behaviors throughout childhood, adolescence, and adulthood, particularly in males. It is suggested that high fetal/circulating testosterone interactively influence the maturation and functionality of mesolimbic dopaminergic circuitry, right orbitofrontal cortex, and cortico-subcortical connectivity, resulting in a strong reward motivation, low social sensitivity, and dampened regulation of strong motivational/emotional processes. The link between these testosterone induced endophenotypes and actual display of antisocial behavior is strongly modulated by different social (e.g., social rejection, low SES) and genetic (e.g., MAOA, 5HTT) risk factors that can disturb socio-, psycho-, and biological development and interact with testosterone in shaping behavior. When these additional risk factors are present, the testosterone induced endophenotypes may increase the risk for a chronic antisocial lifestyle. However, behavioral endophenotypes induced by testosterone can also predispose towards socially adaptive traits such as a strong achievement motivation, leadership, fair bargaining behaviors, and social assertiveness. These adaptive traits are more likely to emerge when the high testosterone individual has positive social experiences that promote prosocial behaviors such as strong and secure attachments with his caregivers, affiliation with prosocial peers, and sufficient socioeconomic resources. A theoretical model is presented, various hypotheses are examined, and future venues for research are discussed.
... 1 (.00) 0 (0.0%) "High aggression scores were associated with high directional asymmetry of 2D:4D and masculinized (low) right hand 2D:4D, only in females and under high provocation" (p. 558) 7. Blanchard and Lyons (2010) "Numerous behaviours and personality traits in children and adults have been evidenced as correlates of the 2D:4D ratio" (pp. 23-24) ...
... It is also worth mentioning that contrary to expectations, a study of 2D:4D and self-reported psychopathy among females found a significant positive correlation (Blanchard & Lyons, 2010). And a twocountry study of children with externalizing behavior concluded that 2D:4D was significantly correlated inversely with such behavior (as expected) in an Austrian sample but not in a British sample (Fink, Manning, Williams, & Podmore-Nappin, 2007). ...
Article
Evolutionary neuroandrogenic (ENA) theory asserts that brain exposed to androgens plus the brain's ability to learn accounts for most of the sex and age variations in criminal behavior. Here, the theory is extended to explain race/ethnic variations in offending. The article documents that among seven different racial/ethnic groups, blacks have the highest and East Asians have the lowest criminal involvement. Strictly social environmental explanations for race/ethnic differences in criminality appear to be inadequate for explaining these differences. Two main elements of ENA theory are offered in the present context: (a) criminal behavior is promoted by exposing the brain to testosterone and other androgens. (b) rapid postpubertal declines in offending depend heavily on learning ability. Ten lines of evidence concerning average racial/ethnic variations in androgen exposure are reviewed, and four lines of evidence of racial/ethnic differences in learning ability are reviewed. With some exceptions and qualifications, currently-available evidence seems to support the idea that racial/ethnic variations in offending could be at least partially explained by ENA theory. Closing comments are offered to suggest that biosocial approaches to the study of racial/ethnic variations in criminal behavior can help to supplement strictly social environmental theories in criminology.
... However, research in this area is contradictory. Blanchard and Lyons (2010) suggested that a higher finger-length ratio is associated with psychopathy in women and callous affect in men, thus contradicting that more feminine finger-length ratios are associated with empathy. Further research is needed to determine the exact relationship between these variables. ...
... In a British study of offenders and nonoffenders, the former group had a lower mean 2D:4D, but the difference failed to reach statistical significance (Anderson, 2012). Digit ratio was found to be positively related to a self-report measure of psychopathy among a sample of British females (Blanchard & Lyons, 2010). In other words, participants with female-typical ratios had higher psychopathy scores. ...
Article
Research on the relationship between prenatal testosterone and criminal behavior has produced mixed results. The 2D:4D digit ratio is typically employed as the measure of prenatal testosterone, but its proxy nature might play a role in the inconsistent findings. This study examines the usefulness of a multi-item approach to the measurement of organizational androgens. Principal components factor analysis of data from a convenient sample of adults reveals that two factors emerge from five androgen-promoted trait items. These two factors, however, do not predict self-reported criminal behavior better than the single right-hand 2D:4D digit ratio item. It is concluded that a multi-item measurement strategy is unlikely to be a more predictive measure of organizational androgens than digit ratio.
... In women, PT is related to low empathy and aggression (Benderlioglu & Nelson, 2004;Kempe & Heffernan, 2011). Only one study previously has investigated PT and psychopathy (Blanchard & Lyons, 2010), and contrary to expectations, found higher levels of prenatal estrogen were associated with overall psychopathy in females and callous affect in males. Nevertheless, the general lack of research on psychopathy in this area highlights the need for further investigation. ...
Article
Psychopathy is generally considered to be a male adaptation. While studies have elucidated a relationship to freely circulating testosterone, less is known about the role of prenatal testosterone (PT) in the development of primary and secondary psychopathy and how this pertains to sex differences. In this study (N = 148), digit ratio (2D:4D) was used to investigate the relationship between prenatal testosterone and primary and secondary psychopathy. In addition, quality of recalled maternal bonding was measured to see if postnatal experience could affect the influence of PT on psychopathic behaviours. Low LH2D:4D predicted primary and secondary psychopathy in women. In men, low maternal care predicted primary psychopathy and high maternal protection predicted secondary psychopathy. Low maternal care also predicted primary psychopathy in women. Lower levels of maternal care and higher levels of maternal control contributed to primary psychopathy above and beyond PT. Lower levels of maternal care were also an influential factor for secondary psychopathy above and beyond PT, although higher levels of mother control were not.
... So far, evidence for an association between the 2D:4D ratio and offending is quite limited. In terms of indirect evidence, one study reported that the 2D:4D ratio was lower (i.e., indicating higher prenatal androgens) among persons who scored high in psychopathy (Blanchard & Lyons, 2010). The ratio was also low among males who were unusually high in aggression and risk taking (Hönekopp, 2011). ...
Article
Full-text available
A decade old theory hypothesizes that brain exposure to androgens promotes involvement in criminal behavior. General support for this hypothesis has been provided by studies of postpubertal circulating levels of testosterone, at least among males. However, the theory also predicts that for both genders, prenatal androgens will be positively correlated with persistent offending, an idea for which no evidence currently exists. The present study used an indirect measure of prenatal androgen exposure— the relative length of the second and fourth fingers of the right hand (r2D:4D)—to test the hypothesis that elevated prenatal androgens promote criminal tendencies later in life for males and females. Questionnaires were administered to 2,059 college students in Malaysia and 1,291 college students in the United States. Respondents reported their r2D:4D relative finger lengths along with involvement in 13 categories of delinquent and criminal acts. Statistically significant correlations between the commission of most types of offenses and r2D:4D ratios were found for males and females even after controlling for age. It is concluded that high exposure to androgens during prenatal development contributes to most forms of offending following the onset of puberty.
... This theory predicts that 2D:4D ratios in both genders correlate with autistic characteristics, such that lower ratios are associated with ASD traits, less empathy and a more systemizing cognitive stance [8]. Past studies have yielded mixed results [38,39,53], and have largely not been replicated; furthermore, most studies to the date have relied on relatively small samples, which limited their power to detect effects. A large community-based study by Manning and colleagues [35], the largest to date, found a significant negative correlation (males r = −0.013; ...
Article
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Background: Recent research investigating the extreme male brain theory of autism spectrum disorders (ASD) has drawn attention to the possibility that autistic type social difficulties may be associated with high prenatal testosterone exposure. This study aims to investigate the association between social communication and emotion recognition difficulties and second to fourth digit ratio (2D:4D) and circulating maternal testosterone during pregnancy in a large community-based cohort: the Avon Longitudinal Study of Parents and Children (ALSPAC). A secondary aim is to investigate possible gender differences in the associations. Methods: Data on social communication (Social and Communication Disorders Checklist, N = 7165), emotion recognition (emotional triangles, N = 5844 and diagnostics analysis of non-verbal accuracy, N = 7488) and 2D:4D (second to fourth digit ratio, N = 7159) were collected in childhood and early adolescence from questionnaires and face-to-face assessments. Complete data was available on 3515 children. Maternal circulating testosterone during pregnancy was available in a subsample of 89 children. Results: Males had lower 2D:4D ratios than females [t (3513) = -9.775, p < 0.001]. An association was found between measures of social communication and emotion recognition, and the lowest 10 % of 2D:4D ratios. A significant association was found between maternal circulating testosterone and left hand 2D:4D [OR = 1.65, 95 % CI 1.1-2.4, p < 0.01]. Conclusions: Previous findings on the association between 2D:4D and social communication difficulties were not confirmed. A novel association between an extreme measure of 2D:4D in males suggests threshold effects and warrants replication.
... In Study 1, high psychopathy and narcissist faces were rated as the most masculine ones, supporting previous studies that have found that psychopathy and narcissism (but not Machiavellianism) relates to other and self-perceived dominance (Rauthmann, 2012;Rauthmann & Kolar, 2013), and ruthless self-advancement in status competition (Jonason, Honey, & Semenyna, 2014). Although the association between psychopathy and prenatal testosterone is still somewhat unclear (Blanchard & Lyons, 2010), previous studies have found that high psychopathy and narcissism relate to increased testosterone, sometimes as a response to stressful social situations (Glenn, Raine, Schug, Gao, & Granger, 2011;Lobbestael, Baumeister, Fiebig, & Eckel, 2014;Welker, Lozoya, Campbell, Neumann, & Carré, 2014). Future studies should try to elucidate the links between the Dark Triad in relation to prenatal and circulating testosterone. ...
Article
Although the Dark Triad of personality (i.e., Machiavellianism, narcissism, and psychopathy) has been researched widely, few studies have looked at women’s preferences for men who are high and low in Dark Triad. Further, it is not clear what the relationships between the Dark Triad and facial masculinity are. We investigated female preference for computer manipulated Dark Triad male faces in two on-line studies (Study 1: n = 125; Study 2: n = 1633). We found that women rated the high psychopathy and narcissistic faces the most masculine (Study 1). We also found that women showed a low preference for the high morphs in both long and short term relationships, and that preference for masculinity was correlated with a preference for narcissism (Study 2). We discuss the results in terms of male and female mating strategies
... So far, evidence for an association between the 2D:4D ratio and offending is quite limited. In terms of indirect evidence, one study reported that the 2D:4D ratio was lower (i.e., indicating higher prenatal androgens) among persons who scored high in psychopathy (Blanchard & Lyons, 2010). The ratio was also low among males who were unusually high in aggression and risk taking (Hönekopp, 2011). ...
Article
Full-text available
A decade old theory hypothesizes that brain exposure to androgens promotes involvement in criminal behavior. General support for this hypothesis has been provided by studies of postpubertal circulating levels of testosterone, at least among males. However, the theory also predicts that for both genders, prenatal androgens will be positively correlated with persistent offending, an idea for which no evidence currently exists. The present study used an indirect measure of prenatal androgen exposure-the relative length of the second and fourth fingers of the right hand (r2D:4D)-to test the hypothesis that elevated prenatal androgens promote criminal tendencies later in life for males and females. Questionnaires were administered to 2,059 college students in Malaysia and 1,291 college students in the United States. Respondents reported their r2D:4D relative finger lengths along with involvement in 13 categories of delinquent and criminal acts. Statistically significant correlations between the commission of most types of offenses and r2D:4D ratios were found for males and females even after controlling for age. It is concluded that high exposure to androgens during prenatal development contributes to most forms of offending following the onset of puberty.
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A personal identification is one of the significant aspects of forensic investigation. Every part of human body has more or less constant relationship with stature. The appendages of the body represent specific relationship to the stature. The length of the index (2D) and ring fingers (4D) are under control of prenatal estrogen and testosterone and their ratio is sexually dimorphic trait and remains fairly stable postnatally. This study is to estimate the correlation between the index finger to ring finger ratio with the stature and gender.This cross-sectional study support that there is positive result with negative correlation between index to ring finger ratio (2D:4D) and height and relationship between 2D:4D ratio with stature and gender. Thus, we can predict height and gender based on 2D:4D ratio.
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Baron-Cohen’s Extreme Male Brain theory of autism has generated a novel perspective of psychological disorders: the depiction of clinical behavioral patterns as extreme expressions of normal sex differences. Consistent with this view, this review suggests that histrionic, borderline, and dependent personality disorders are the best candidates to represent the extreme female brain, as they are all characterized by excessive social or empathizing needs, and are related to feminization.
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Boys are more likely than girls to be diagnosed with an autism spectrum disorder (ASD). The extreme male brain (EMB) theory of ASD suggests that fetal testosterone (FT) exposure may underlie sex differences in autistic traits. A link between the organizational effects of FT on the brain and ASD is often drawn based on research using digit ratio (2D:4D), a putative biomarker, without a full survey of the findings. This paper critically and quantitatively reviews the research on the relationship between 2D:4D and ASD as well as autism spectrum, empathizing, and systemizing measures in neurotypical populations. Overall, there is some support for the EMB theory in all four areas, particularly the 2D:4D-ASD relationship. Recommendations for future research are provided.
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The relative length of the second (index) to the fourth (ring) finger (2D:4D) is a putative negative correlate of prenatal testosterone (T) exposure. Therefore, 2D:4D (and to a lesser extent D(r-l), the difference between 2D:4D in the right hand and in the left hand) has often been used to study effects of prenatal androgenization on human behavior and cognition. However, evidence suggests that 2D:4D may also be related to levels of circulating sex hormones in adults. This would question the validity of 2D:4D as a means of studying the effects of prenatal sex hormones. Here we present new data from two non-clinical samples (64 women and 102 men) regarding the relationships of 2D:4D and D(r-l) with circulating sex hormone levels. We then present a meta-analytic review of all the present evidence regarding this issue. The results suggest that, in the normal population, 2D:4D and D(r-l) are not associated with adult sex hormone levels. The findings from this current study add to the growing body of evidence demonstrating that 2D:4D is a suitable tool to study the effects of prenatal androgenization on human behavior and cognition.
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The purpose of the present study was to examine the factor structure of the Multidimensional Aptitude Battery (MAB) and also the extent of overlap between the MAB and the Wechsler Adult Intelligence Scales–Revised (WAIS-R). The sample consisted of 55 men and 30 women who were administered the WAIS-R and the MAB. Factor analysis showed that the MAB assesses two distinct aspects of intelligence: verbal and performance abilities. The validity coefficients indicated there was substantial overlap between the WAIS-R and MAB Verbal, Performance, and Total scale scores. However, 4 of the 10 MAB subtests did not correlate with the WAIS-R subscales they were designed to represent. It was concluded that the MAB is a suitable alternative to the WAIS-R when an indication of verbal, performance, or general abilities is required; however, the MAB should not be used when detailed information is required on specific abilities.
Article
The ratio between second and fourth digit lengths (digit ratio) is known to be sexually dimorphic, with males having lower values. It is believed that digit ratio acts as a marker of pre-natal testosterone exposure and a number of studies of its correlates support this idea. In the present study, associations between digit ratio and a number of cognitive and personality tests which are known to show male–female score differences were investigated. Evidence for associations in the expected direction was found for sensation seeking, psychoticism and neuroticism, in all cases for females only. No association was found between digit ratio and cognitive test scores.
Article
Several studies have demonstrated that the ratio between the lengths of the second and fourth digits (2D:4D) is sexually dimorphic. On average males demonstrate lower digit ratios than do females. There is accumulating evidence that 2D:4D is established early in development and is negatively related to prenatal testosterone and positively with prenatal estrogen. In this present study, we investigated associations between digit ratio and the ‘big-five’ personality factors (extraversion, neuroticism, openness, conscientiousness and agreeableness). Only agreeableness showed a significant sex difference with females scoring higher. Neuroticism showed a significant positive correlation with right hand digit ratio for the whole sample, and in females only for right hand 2D:4D. Further, a significant negative association was found between females’ right hand digit ratio and agreeableness. Male 2D:4D did not correlate significantly with any of the personality factors. The results follow previous studies reporting that 2D:4D was a stronger correlate of personality traits in females than in males. In summary, the associations between digit ratio and personality factors are weak but provide some further support for the claim that gender-related behaviour is affected by the amount of steroid hormones present during critical periods of prenatal development.
Article
A large body of research has revealed that digit length ratios (2D:4D) are influenced by exposure to prenatal androgens. It is thought that higher exposure to prenatal androgens leads to the development of more masculinized (smaller) digit ratios. Low 2D:4D, particularly low right 2D:4D and low right–left 2D:4D (directional asymmetry or DA) has been linked with a number of behavioral traits which are sex-dependent, including performance in sports and exercise, and to some degree, aggression. To date, the focus of digit ratio research has been on physical aggression, however, 2D:4D has never been linked with indirect aggression (also called social or relational aggression), a form of aggression often preferred by women. We measured the 2D:4D of 100 women and compared these scores with responses on indirect and direct aggression questionnaires. Although 2D:4D was not linked to direct aggression in women, we found that low DA predicted indirect aggression. We conclude that higher levels of prenatal testosterone induce higher levels of aggression, and that the link between prenatal testosterone and aggression in women is most strongly seen for indirect aggression.
Article
Traditional conceptualizations of psychopathy highlight the importance of affective features as they relate to social deviance; however, little empirical research has actually investigated specific roles of emotion and emotion processing with respect to antisocial conduct. Antisocial personality disorder (APD), prevalent in forensic populations, is commonly associated with psychopathy despite the notable omission of such core affective features in its diagnosis. In this paper, we review the empirical literature on the contribution of emotion to psychopathy and APD, highlighting in particular research on emotion processing and various facets of emotional expression, including empathy and alexithymia. Research findings are discussed on gender differences in emotional functioning and their likely effects on the assessment of psychopathy and APD. Given the known gender differences in the expressions of emotion, the article concludes with recommendations to bridge research for different offender groups, including psychopathy and APD.
Article
Sensation seeking has been described as a trait referring to the tendency to seek novel, varied, complex, and intense sensations and experiences; and the willingness to take risks for the sake of such experiences. Explanations for sensation seeking have been based upon genetic, evolutionary, psychophysiological, and sociocultural models. This study further examines the possibility that prenatal hormones – as measured via 2D:4D finger length ratio – may influence the development of certain personality characteristics associated with sensation seeking (Austin, Manning, McInroy, & Mathews, 2002). We studied the relationship between 2D:4D ratios, a supposed proxy for prenatal testosterone (T), and sensation seeking as assessed by the Sensation Seeking Scale Form V (SSS-V) in a sample of 278 German and UK University students. There were significant sex differences for 2D:4D and on the SSS-V, with males having lower 2D:4D ratios, but higher SSS-V scores. Furthermore, right- and left-hand 2D:4D in males was significantly negatively associated with total sensation seeking score, and the boredom subscale. No significant associations were found for women. Since low 2D:4D is supposed to indicate exposure to higher levels of T in utero, our data suggest that there may be an organizational effect of T which influences later development of sensation seeking personality characteristics in men.
Article
The present study examined the reliability and validity of the Psychopathy Checklist-Revised: Screening Version (PCL-R:SV; Hart, Cox & Hare, 1995, Manual for the Screening Version of the Hare Psychopathy Checklist—Revised (PCL-R:SV)) in a sample of 75 male and 75 female university students. We examined the internal structure of the PCL-R:SV and its relationship to a battery of self-report measures relevant to the construct of psychopathy. Results indicated that the PCL-R:SV had good internal consistency and interrater reliability. The distribution of psychopathy scores were significantly higher among the males than the females. A factor analysis failed to confirm the two factor structure of psychopathy previously found in forensic samples. PCL-R:SV Total scores were significantly correlated with Antisocial Personality Disorder symptoms, substance use, self-reported criminal activity, and observer ratings of interpersonal behavior. Overall, the results suggest that the PCL-R:SV is a reliable and valid measure of psychopathic traits in nonforensic populations.
Article
The second-to-fourth digit ratio (2D:4D) is sexually differentiated and is a likely biomarker for the organisational (permanent) effects of prenatal testosterone on the human brain. Recent research has highlighted a possible role of prenatal testosterone levels in both the etiology of autism-spectrum disorders and in sex and individual differences in cognitive styles of the normal mind (Baron-Cohen’s Extreme Male Brain Theory of Autism and Empathising/Systemising Theory). Importantly, autistic children present lower (hypermasculinised) 2D:4D than healthy controls. Based on these accounts, we investigated the relation of 2D:4D with Baron-Cohen’s measures of empathising (“Reading the Mind in the Eyes” test, RMET; Empathy Quotient, EQ), systemising (Systemising Quotient, SQ), and autistic-like traits (Autism-Spectrum Quotient, AQ) in the general population (N = 423 Austrian adults). Whereas sex differences into the expected direction and of expected size were obtained for all variables and internal scale consistencies tallied to retrievable reference values, 2D:4D was unrelated to RMET, EQ, SQ, and AQ scores. Candidate explanations for this lack of correlation might be possible developmental timing differences in the expression of 2D:4D and empathising/systemising, qualitative (as opposed to quantitative) functional differences between the normal and the autistic mind, or the suboptimal psychometric properties of the measures.
Article
The authors examined the association between psychopathy and identification of facial expressions of emotion. Previous research in this area is scant and has produced contradictory findings (Blair et. al., 2001, 2004; Glass & Newman, 2006; Kosson et al., 2002). One hundred and forty-five male jail inmates, rated using the Hare Psychopathy Checklist: Screening Version participated in a facial affect recognition task. Participants were shown faces containing one of five emotions (happiness, sadness, fear, anger, or shame) displayed at one of two different levels of intensity of expression (100% or 60%). The authors predicted that psychopathy would be associated with decreased affect recognition, particularly for sad and fearful emotional expressions, and decreased recognition of less intense displays of facial affect. Results were largely consistent with expectations in that psychopathy was negatively correlated with overall facial recognition of affect, sad facial affect, and recognition of less intense displays of affect. An unexpected negative correlation with recognition of happy facial affect was also found. These results suggest that psychopathy may be associated with a general deficit in affect recognition.
Article
The Axis II Work Group of the Task Force on DSM-IV has expressed concern that antisocial personality disorder (APD) criteria are too long and cumbersome and that they focus on antisocial behaviors rather than personality traits central to traditional conceptions of psychopathy and to international criteria. We describe an alternative to the approach taken in the rev. 3rd ed. of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R; American Psychiatric Association, 1987), namely, the revised Psychopathy Checklist. We also discuss the multisite APD field trials designed to evaluate and compare four criteria sets: the DSM-III-R criteria, a shortened list of these criteria, the criteria for dyssocial personality disorder from the 10th ed. of the International Classification of Diseases (World Health Organization, 1990), and a 10-item criteria set for psychopathic personality disorder derived from the revised Psychopathy Checklist.
Article
Psychopaths have been described as human predators who use charm, intimidation, and violence to control others and to satisfy their own needs. Underlying their propensity to violate social norms and expectations is a profound lack of empathy, guilt, or remorse, affective processes that have long resisted scientific investigation. Using brain imaging technology we found that psychopaths differed from nonpsychopaths in the pattern of relative cerebral blood flow during processing of emotional words. The results were consistent with the hypothesis that there are anomalies in the way psychopaths process semantic and affective information.
Article
Hand preferences and language lateralization were assessed in women exposed prenatally to the synthetic estrogen, diethylstilbestrol (DES), and in their unexposed sisters. The DES-exposed women showed an increased degree of hand preference (regardless of direction) and were more likely to be left handed for writing. However, the groups did not differ significantly on a dichotic listening measure of language lateralization. Perhaps as a result of the alterations in hand preferences, the typical relationship between hand preferences and language lateralization was disrupted in the DES-exposed group. Also, within the DES-exposed group, exposure early in gestation correlated with left handedness whereas exposure late in gestation correlated with reduced left ear (right hemisphere) scores on the verbal dichotic task. Results are discussed in terms of theoretical perspectives predicting hormonal influences on sexual differentiation of hemispheric asymmetry and in terms of separate critical periods for hormonal effects on individual sexually differentiated characteristics.
Article
The steroid hormone estrogen influences brain function and neuropsychiatric disorders, but neuroanatomical information about the estrogen receptors (ERs) are rather limited. The main focus of this article is to provide an overview of the current status of the ER distribution and possible function in the human brain. The ERs are ligand activated transcription factors that belong to the steroid hormone receptors, included in the nuclear receptor superfamily. To date, there are two known ER subtypes, alpha and beta. In the human forebrain, both estrogen receptor subtypes are predominantly expressed in limbic-related areas, although they show distinct distribution patterns. The ERalpha mRNA expression appears to dominate in the hypothalamus and amygdala, indicating that the alpha-subtype might modulate neuronal cell populations involved in autonomic and reproductive neuroendocrine functions as well as emotional interpretation and processing. In contrast, the hippocampal formation, entorhinal cortex, and thalamus appear to be ERbeta dominant areas, suggesting a putative role for ERbeta in cognition, non-emotional memory and motor functions. Clinical observations of estrogenic effects together with the information available today regarding ER expression in the primate brain provide important clues as to the functional aspects of the two ER subtypes. However, further characterization of the different phenotypes of the ER expressing cells in the human brain is needed as well as the delineation of the genes which are regulated by the ERs and how this transcriptional control correlates with human behavior and mental status.
Article
In 1997 in this Journal we published the "Reading the Mind in the Eyes" Test, as a measure of adult "mentalising". Whilst that test succeeded in discriminating a group of adults with Asperger syndrome (AS) or high-functioning autism (HFA) from controls, it suffered from several psychometric problems. In this paper these limitations are rectified by revising the test. The Revised Eyes Test was administered to a group of adults with AS or HFA (N = 15) and again discriminated these from a large number of normal controls (N = 239) drawn from different samples. In both the clinical and control groups the Eyes Test was inversely correlated with the Autism Spectrum Quotient (the AQ), a measure of autistic traits in adults of normal intelligence. The Revised Eyes Test has improved power to detect subtle individual differences in social sensitivity.
Article
The key mental domains in which sex differences have traditionally been studied are verbal and spatial abilities. In this article I suggest that two neglected dimensions for understanding human sex differences are 'empathising' and 'systemising'. The male brain is a defined psychometrically as those individuals in whom systemising is significantly better than empathising, and the female brain is defined as the opposite cognitive profile. Using these definitions, autism can be considered as an extreme of the normal male profile. There is increasing psychological evidence for the extreme male brain theory of autism.
Article
Although the correlates and causes of psychopathy and antisocial personality disorder (ASPD) have been the subject of extensive investigation, researchers in this area have until recently focused almost exclusively on males. As a consequence, relatively little is known about psychopathy and ASPD in females. In this paper, we review the empirical literature on sex differences in the base rates, mean symptom levels, correlates, and factor structure of psychopathy and ASPD. In addition, we discuss the potential sex-differentiated phenotypic expressions of psychopathy and ASPD (e.g., somatization disorder [SD]) as well as sex differences in the developmental trajectories of these conditions. There is suggestive evidence that these conditions may be differentially expressed across biological sex, although further investigation of this issue is warranted. We conclude with recommendations for future research in this area, including suggestions for embedding the study of sex differences in psychopathy and ASPD within a construct validational framework.
Article
The ratio of 2nd to 4th digit length (2D:4D) is sexually dimorphic (mean 2D:4D is lower in males than females) and is thought to be fixed early in development. 2D:4D has been reported to be related to fetal growth, hand preference, autism, Asperger's syndrome, sperm counts, family size, age at myocardial infarction in men and breast cancer in women. There is indirect evidence that 2D:4D is established in utero and is negatively related to prenatal testosterone and positively with prenatal estradiol. However, there are no studies which show direct relationships between fetal testosterone (FT), fetal estradiol (FE) and 2D:4D. To investigate the relationships between 2D:4D ratios and FT and FE from amniotic fluid. Cohort study. 33 children. Radioimmunoassays of FT and FE obtained from routine amniocentesis; 2D:4D ratios calculated from 2nd and 4th digit length of the right and left hands at age 2 years. A significant negative association between right 2D:4D ratio and FT/FE ratio, which was independent of sex. These preliminary findings lend support to an association between low 2D:4D and high levels of FT relative to FE, and high 2D:4D with low FT relative to FE.
Article
Animal research has demonstrated reductions in punishment sensitivity and enhanced reward dependency after testosterone administration. In humans, elevated levels of testosterone have been associated with violent and antisocial behavior. Interestingly, extreme forms of violent and antisocial behavior can be observed in the psychopath. Moreover, it has been argued that reduced punishment sensitivity and heightened reward dependency are crucially involved in the etiology and maintenance of psychopathy. A task that has been proven to be capable of simulating punishment-reward contingencies is the IOWA gambling task. Decisions to choose from decks of cards become motivated by punishment and reward schedules inherent in the task. Importantly, clinical and subclinical psychopaths demonstrate a risky, disadvantageous pattern of decision-making in the task, indicating motivational imbalance (insensitivity for punishment and enhanced reward dependency). Here, in a double-blind placebo-controlled crossover design (n = 12), whether a single administration of testosterone would shift the motivational balance between the sensitivity for punishment and reward towards this tendency to choose disadvantageously was investigated. As hypothesized, subjects showed a more disadvantageous pattern of decision-making after testosterone compared to placebo administration. These findings not only provide the first direct evidence for the effects of testosterone on punishment-reward contingencies in humans, but they also give further insights into the hypothetical link between testosterone and psychopathy.
Article
There have been suggestions that Theory of Mind (ToM) impairment might lead to aggressive behaviour and psychopathy. Psychopathic and matched non-psychopathic individuals, as defined by the Hare Psychopathy Checklist [The Hare Psychopath Checklist-Revised, 1991] completed the 'Reading the Mind in the Eyes' ToM Test [Journal of Child Psychology and Psychiatry, 1997;38:813]. This test requires the self-paced identification of mental states from photographs of the eye region alone. Results indicated that the psychopathic individuals did not present with any generalised impairment in ToM. The data are discussed with reference to the putative neural system mediating performance on this task and models of psychopathy.
Article
Finger length ratio (2D:4D) is a sexually dimorphic trait. Men have relatively shorter second digits (index fingers) than fourth digits (ring fingers). Smaller, more masculine, digit ratios are thought to be associated with either higher prenatal testosterone levels or greater sensitivity to androgens, or both. Men with more masculine finger ratios are perceived as being more masculine and dominant by female observers, and tend to perform better in a number of physical sports. We hypothesized that digit ratio would correlate with propensity to engage in aggressive behavior. We examined the relationship between trait aggression, assayed using a questionnaire, and finger length ratio in both men and women. Men with lower, more masculine, finger length ratios had higher trait physical aggression scores (r(partial) = -0.21, N = 134, P = 0.028). We found no correlation between finger length ratio and any form of aggression in females. These results are consistent with the hypothesis that testosterone has an organizational effect on adult physical aggression in men.
Article
The influence of sex steroids upon brain development has been suggested to mediate sex differences in developmental psychopathology. The ratio of the length of index finger or second finger to the ring finger or fourth finger (the 2D:4D ratio) appears to be a marker of early sex hormone exposure, with low 2D:4D associated with high prenatal testosterone and high 2D:4D associated with high prenatal oestrogen. This relationship allows a non-invasive measure of the long-term influence of prenatal sex steroids. Behaviours such as hyperactivity and poor social cognition are common in preschoolers. An association between 2D:4D and these possible precursors of psychopathology would be most readily identified in this group. To identify relationships between 2D:4D ratio and behaviours in preschool children which constitute possible precursors of developmental psychopathology. Population survey. The 2D:4D ratio was measured in a group of preschool children and behavioural questionnaires were given to parents and teachers. Sex differences in behaviours were small, whilst correlations with 2D:4D were strong. Low 2D:4D was related to hyperactivity and poor social cognitive function in girls, and high 2D:4D with emotional symptoms in boys. We suggest that during early brain development androgens increase the probability of hyperactivity and poor social cognition in girls. Early oestrogens increase the probability of emotional problems in boys.
Article
Although high baseline testosterone levels correlate with low empathy, there is no causal evidence for this association in humans. The present study tested the causality of this relationship by manipulating testosterone levels in a double-blind placebo controlled crossover design. 20 healthy female participants received either a sublingual administration of a single dose of testosterone or placebo on 2 days and were tested 4 h after administration. Because research has shown that facial expression mimicry is a non-obtrusive index of empathy, facial electromyography was measured in response to dynamic facial expressions of happy and angry faces. Results showed that testosterone generally decreased facial mimicry. These findings are consistent with models that assign a critical role to mimicry in the ability to develop and communicate empathy towards conspecifics, and provide a potential causal mechanism of effects of testosterone on empathy.
Article
Maternal smoking during pregnancy is linked to high fetal testosterone (FT), and an increased risk in offspring for autism, ADHD, conduct disorder, antisocial behaviour and criminal outcomes. The ratio of the length of the 2nd and 4th fingers (2D:4D) is thought to be negatively related to FT concentration, and is related to autism, hyperactivity, poor social behaviour, and physical aggression. We compare the 2D:4D ratio of children whose mothers smoked during pregnancy with the 2D:4D of children whose mother did not smoke. Cross-sectional survey in two primary schools. Questionnaires were distributed to 710 children and 546 were returned. Of these the 2nd and 4th digits of 520 children (259 females and 261 males) were measured. The main outcome measures were 2nd and 4th digit length, smoking history of mother and father. Boys had lower mean 2D:4D than girls and right 2D:4D was lower than left. Among boys, those whose mother's smoked during pregnancy had lower right hand 2D:4D ratio than those whose mother did not smoke. The difference remained significant after the effects of age, height, weight and birth weight were removed. Other household smoking patterns were not associated with male offspring 2D:4D. Female offspring 2D:4D did not differ on the basis of maternal smoking. Maternal smoking during pregnancy was associated with low right 2D:4D in children, but the effect was restricted to boys. A link between maternal smoking during pregnancy and 2D:4D supports a causal association between FT and such behaviours as hyperactivity and conduct disorder.
Article
In this paper, I am going to examine the disorder of psychopathy and consider how genetic anomalies could give rise to the relatively specific neuro-cognitive impairments seen in individuals with this disorder. I will argue that genetic anomalies in psychopathy reduce the salience of punishment information (perhaps as a function of noradrenergic disturbance). I will argue that the ability of the amygdala to form the stimulus-punishment associations necessary for successful socialization is disrupted and that because of this, individuals with psychopathy do not learn to avoid actions that will harm others. It is noted that this model follows the neuropsychological approach to the study of developmental disorders, an approach that has been recently criticized. I will argue that these criticisms are less applicable to psychopathy. Indeed, animal work on the development of the neural systems necessary for emotion, does not support a constructivist approach with respect to affect. Importantly, such work indicates that while environmental effects can alter the responsiveness of the basic neural architecture mediating emotion, environmental effects do not construct this architecture. However, caveats to the neuropsychological approach with reference to this disorder are noted.
What's wrong with Bonferroni adjustments
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Perneger T (2003) What's wrong with Bonferroni adjustments. British Medical Journal 316.
press) Manual for the Self-Report Psychopathy scale
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Paulhus DL, Hemphill JD & Hare RD (in press) Manual for the Self-Report Psychopathy scale. Toronto: Multi- Health Systems.
Scoring Pamphlet for the Sel-Report Psychopathy scale: SRP- II.' Unpublished document
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Hare RD, Harpur TJ & Hemphill JF (1989) 'Scoring Pamphlet for the Sel-Report Psychopathy scale: SRP- II.' Unpublished document. Vancouver: Simon Fraser University.