Glenn D. Wilson

Sexual orientation and the 2nd to 4th finger length ratio: evidence for organising effects of sex hormones or developmental instability?

It has been proposed that human sexual orientation is influenced by prenatal sex hormones. Some evidence examining putative somatic markers of prenatal sex hormones supports this assumption. An alternative suggestion has been that homosexuality may be due to general developmental disruptions independent of hormonal effects. This study investigated the ratio of the 2nd to 4th finger digits (the 2D:4D ratio), a measure often ascribed to the organisational actions of prenatal androgens, and the fluctuating asymmetry (FA-a measure of general developmental disruption) of these features, in a sample of 240 healthy, right handed and exclusively heterosexual and homosexual males and females (N=60 per group). Homosexual males and females showed significantly lower 2D:4D ratios in comparison to heterosexuals, but sexual orientation did not relate to any measures of FA. The evidence may suggest that homosexual males and females have been exposed to non-disruptive, but elevated levels of androgens in utero. However, these data also draw attention to difficulties in the interpretation of results when somatic features are employed as biological markers of prenatal hormonal influences.

Personality, time of day and arousal.

Sixty-one men and 50 women measured their own skin conductance hourly throughout one working day as well as recording drug intake and activities; they also completed the EPQ, I7 and Morningness-Eveningness questionnaires. As expected, self-reported Morning types showed higher skin conductance in the morning and Evening types in the evening. Introverts appeared as more highly aroused than extroverts, but particularly so in the morning; by midnight the two personality types had converged in skin conductance. Sociability, rather than impulsiveness, seemed to be the component of extraversion responsible for this interaction. Women showed higher conductance in the early morning, men in the afternoon and evening. Indications were that activity was determining arousal rather than the other way about, and that drug use was socially rather than neurologically motivated.

Born gay? The psychobiology of human sexual orientation

Sexual orientation is fundamental to evolution and shifts from the species-typical pattern of heterosexuality may represent biological variations. The growth of scientific knowledge concerning the biology of sexual orientation during the past decade has been considerable. Sexual orientation is characterised by a bipolar distribution and is related to fraternal birth order in males. In females, its distribution is more variable; females being less prone towards exclusive homosexuality. In both sexes homosexuality is strongly associated with childhood gender nonconformity. Genetic evidence suggests a heritable component and putative gene loci on the X chromosome. Homosexuality may have evolved to promote same sex affiliation through a conserved neurodevelopmental mechanism. Recent findings suggest this mechanism involves atypical neurohormonal differentiation of the brain. Key areas for future research include the neurobiological basis of preferred sexual targets and correlates of female homosexuality.

PERSONALITY AND AFFECTIVE MODULATION OF THE STARTLE REFLEX

Abstract The human startle reflex, as indexed by strength of eyeblink to a sudden, loud noise, has been shown to vary according to the presence of pleasant and unpleasant stimuli. An experiment was conducted to determine whether this effect is in turn dependent on the personality of the subject. Subjects viewed a series of slides classified as pleasant, unpleasant or neutral, with acoustic startle probes being presented unpreditably during and between slides. Electromyographic (EMG) measures of eyeblink responses confirmed the expected pattern of modulation, with pleasant slides reducing and unpleasant slides increasing the amplitude of startle. Harm Avoidance (HA), as measured by Cloningers Tridimensional Personality Questionnaire (TPQ), mediated these effects: only subjects high in HA showed modulation to unpleasant slides, while only subjects low in HA showed modulation to pleasant slides. Affective modulation, as measured by response latency, was mediated by Extraversion (E) and Neuroticism (N), as measured by the Eysenck Personality Questionnaire (EPQ): only subjects who were extraverted and stable showed the expected linear pattern of modulated startle. The implications of these data for Cloningers. Grays and Eysencks theories of personality are discussed.

Psychophysiological correlates of behavioural inhibition and activation

Abstract Psychophysiological arousal measures were investigated in relation to scores on behavioural inhibition and activation scales derived from the Gray–Wilson Personality Questionnaire (GWPQ). Ss were 63 psychology students, aged 18–37, whose skin conductance (SC) and heart rate (HR) were recorded before and during a 2-min mental arithmetic task. EEG was recorded in a resting state. The Eysenck Personality Inventory (EPI) and Spielberger State-Trait Anxiety Inventory (STAI) were also administered. Behavioural Inhibition System (BIS) scores [along with Neuroticism (N) and Trait Anxiety (TA)] were related to high beta and gamma EEG activity in frontal areas and low delta and theta activity in temporal, parietal and left frontal areas. Behavioural Activation System (BAS) scores were related to high delta and theta activity in parietal areas and were negatively related to respiratory sinus arrhythmia and HR acceleration during mental arithmetic. These findings are consistent with the hypothesis that behavioural activation is associated with autonomic and cortical underarousal while behavioural inhibition is associated with high cortical arousal, especially in the right hemisphere.

Sex differences in sexual fantasy patterns

Abstract A detailed sexual fantasy questionnaire was completed anonymously and returned by post by a sample of 90 Londoners stratified by sex and social class and representing a 30% return rate. Men and women were equally likely to accept and return the questionnaires. Information was also collected concerning sexual behaviour, libido and satisfaction. Factor analysis revealed four main types of fantasy: (1) Exploratory (e.g., group sex, promiscuity, homosexuality); (2) Intimate (e.g., kissing, oral sex, outdoor love); (3) Impersonal (e.g., watching others, fetishism, using objects for stimulation); and (4) Sadomasochistic (e.g., whipping or spanking, being forced). These four types of fantasy were positively correlated and were all more commonly reported by men, although women were almost as high on the Intimate factor. Women were also more likely to be passive or receptive in their fantasies, and men active. All fantasies were associated with high libido as indicated by self-rated sex drive and orgasm frequency, especially for women. In general, reports of many fantasies went with satisfaction in women but with dissatisfaction (frustration?) in men. This finding is explained in terms of the higher average level of libido in men than women, with the consequent difficulty experienced by men in acting out their desires.

Large sexual-orientation-related differences in performance on mental rotation and judgment of line orientation tasks.

This study examined the performance of heterosexual and homosexual men and women on 2 tests of spatial processing, mental rotation (MR) and Benton Judgment of Line Orientation (JLO). The sample comprised 60 heterosexual men, 60 heterosexual women, 60 homosexual men, and 60 homosexual women. There were significant main effects of gender (men achieving higher scores overall) and Gender x Sexual Orientation interactions. Decomposing these interactions revealed large differences between the male groups in favor of heterosexual men on JLO and MR performance. There was a modest difference between the female groups on MR total correct scores in favor of homosexual women but no differences in MR percentage correct. The evidence suggests possible variations in the parietal cortex between homosexual and heterosexual persons.

Sex, sexual orientation, and identification of positive and negative facial affect

Sex and sexual orientation related differences in processing of happy and sad facial emotions were examined using an experimental facial emotion recognition paradigm with a large sample (N = 240). Analysis of covariance (controlling for age and IQ) revealed that women (irrespective of sexual orientation) had faster reaction times than men for accurate identification of facial emotion and were more accurate in identifying male faces than female ones, whereas men performed the same regardless of the sex of the face. However, there were no overall sex differences in accuracy. These findings suggest a limited role for sex in the perception of facial affect.

Finger-length as an index of assertiveness in women

Abstract A gene causing the index finger to be shorter than the ring finger is said to be dominant in men but recessive in women, with the result that more women have longer forefingers than men. Since this finger-length ratio varies considerably within sex, the possibility that it might relate to masculinity-femininity of social behaviour in women was investigated. Nine hundred and eighty-five women provided self-reports on the length of their fingers and their degree of assertiveness, without knowledge of the hypothesized link. Women whose forefinger was shorter than their ring finger were more likely to describe themselves as ‘assertive and competitive’ than women whose forefinger was longer than their ring finger. This finding could reflect the simultaneous effect of prenatal sex hormones on body and brain.

A factor analysis of the Gray-Wilson personality questionnaire

Abstract Principal components analysis of the Gray-Wilson Personality Questionnaire revealed six fairly independent factors that bore only a partial resemblance to the six animal behaviour paradigms that the test was devised to measure. Taken together with the inter-scale correlations reported previously this raises certain questions about the application of brain systems derived from animal learning studies to the analysis of individual differences at the human level.