女性食物选择的演化视角：基于性选择过程的理论探讨

性选择在人类心理、行为等表型的演化过程中扮演了重要角色,但其对女性食物选择的影响却相对较少被关注。性选择塑造了男女不同的择偶策略,男性择偶时对女性外在吸引力的关注使得女性更加重视身材等外在吸引力信息。而女性身材与饮食的密切联系,进一步提示性选择过程应该会对女性的食物选择产生影响。以之为基础,梳理求偶动机激活可能引发的女性食物选择的变化,以及女性生理期不同阶段在食物选择上的变异,有助于了解性选择过程对女性食物选择的影响。未来研究中,进一步从行为、激素、脑等不同层面剖析对应影响及涉及机制,对该领域的长远发展有重要意义。     

Men's and women's attitudes and beliefs about the menstrual cycle

Recent analyses of menstrual distress have emphasized sociocultural influences. Yet beliefs and attitudes of men—an important socialization force in the lives of women—have received little attention. In the present study, 239 students (156 females and 83 males) from three colleges filled out a survey on expectations for menstrual and premenstrual symptoms, attitudes about mensturation, sources of menstrual-related information, and effects of menstruation upon daily activities. The major findings are as follows: First, although both males and females believed women experience certain cycle-related symptoms, females reported that women experience more severe menstrual and premenstrual symptoms (when compared to intermenstrual ones) than males reported, while males believed women experience more severe menstrual than premenstrual symptoms than females believed. Second, males learned less about menstruation from the majority of possible informational sources and rated most sources as more negative than did the females. Third, males believed that menstruation had more of an effect on women's moods and had a more debilitating effect on women's lives than did females. Fourth, females rated menstruation as more bothersome than did males. Fifth, more males believed their mothers experienced menstrual irritability and moodiness, while more females believed their mothers experienced swelling. The findings are discussed in terms of the role of socialization and the type of information imparted to males and females in America today.     

Monthly fluctuation in task concentration in female college students.

50 university women with consistent and rhythmic menstrual cycles were given Golden's version of the Stroop color-word test to evaluate their concentration accuracy. 50 male undergraduates were also tested as a control sample. The participants took the Stroop test every seven days for four consecutive weeks to allow examination of whether change in the color and word naming activity occurred. A split-plot analysis of the variance of the scores gave a significant difference for the sequence in which the tests were taken, the measures recited during the testing, and the sex of the respondent. When the values for the women were ordered to correspond to stages of their menstrual cycle, the over-all mean accuracy rose slowly to midcycle, then dropped as menses approached. This supports the hypothesis that the women's concentration was at the lowest level during the latter part of the monthly cycle. Women scored significantly higher on the color and word naming task on the Stroop test than men.     

How accurate are women's estimates of date of onset of next menses?

Abstract

Because of individual differences in Occurrence of ovulation and patterns of hormonal secretions, one would usually prefer to measure locus in the menstrual cycle using physiological assessment procedures. But such methods are time consuming and costly. When exploring a new domain for possible relations to the menstrual cycle, it would be cost effective to use the simpler procedure of having each women verbally estimate date of onset of next menses. The accuracy of such estimates was studied in two college age samples. Estimated number of days until next onset correlated highly with actual number of days, as verified by follow-up (r = 0.90). As a group, women neither under- nor overestimated number of days. The precision with which these judgments were made was reasonably high. In sum, when a group of women are followed for one cycle, the average accuracy is very high, certainly high enough to support use of such verbal reports for certain scientific purposes.     

Variations in perception of short time intervals during menstrual cycle

The hypothesis that women experience heightened sensitivity and responsivity premenstrually was tested by asking 10 women to produce short time intervals at four phases of the menstrual cycle. 10 men were assigned to "pseudo-cycles" and tested as a control. The test was based on the assumption that a greater sensitivity to stimuli is reflected in a "slowing down" of subjective time. The women produced the shortest time intervals three to four days before menses, confirming the hypothesis.     

Endocrine, cardiovascular, and psychological correlated of olfactory sensitivity changes during the human menstrual cycle

Signal detection measures olfactory sensitivity (d') and measures of blood pressure, heart rate, body temperature, nasal airflow, and respiration rate were repeatedly established within approximately 2.5-hr test sessions held every other day across 17 menstrual cycles of women not taking oral contraceptives, 6 menstrual cycles of women taking oral contraceptives, and 6 equivalent time periods of three men. In addition, radioimmunoassay-determined serum levels of luteinizing hormone, follicle stimulating hormone, estrone, estradiol, progesterone, and testosterone, as well as responses to the Moos Menstrual Distress Questionnaire (MDQ), were established daily or bidaily throughout the study periods. Peaks in olfactory sensitivity were noted during the second half of menses, midcycle, and midluteally in women taking and in women not taking oral contraceptives. The lack of correlation between the fluctuations in d' and the circulating hormone levels in the group using oral contraceptives suggests factors other than gonadal hormones were responsible for these changes. Significant fluctuations were also noted across the cycle phases of the normally cycling women for all the hormones examined, as well as for body temperature, nasal airflow, and the MDZ Water Retention and Pain Scales. In the oral contraceptive group, very small but statistically significant changes were observed across the cycle in body temperature and in circulating levels of luteinizing hormone and estrone. Interrelations between a number of the variables were noted both within and across the test periods in all three subject groups. The results are discussed in relation to fluctuations reported in a number of sensory systems during the menstrual cycle.     

Effects of menstrual cycle phase on reporting levels of aggression using the buss and perry aggression questionnaire

The Aggression Questionnaire [Buss and Perry, 1992, Journal of Personality and Aggression, vol. 63, pp. 452–459] was administered to women at menses and during the midluteal phase of their menstrual cycles to assess changes in reporting aggressive behavior as a function of menstrual phase. Men served as a control group, and also received the questionnaire twice, once at session I and once at session II. Women at menses reported a significantly higher level of physically aggressive behavior than during the midluteal phase. A similar but non‐significant trend was found for reporting verbal aggression. There were no changes in reporting of anger or hostility across the menstrual cycle. This produced a significant sex‐difference on reporting physical aggression between men and women at the midluteal phase but not at menses. Aggr. Behav. 29:531–538, 2003. © 2003 Wiley‐Liss, Inc.     

Gender differences in eating behavior and body weight regulation

Gender differences in food intake and selection first appear in adolescence. Men consume more calories than women, and the sexes have different eating styles, which indicate that women have been socialized to eat in a more feminine manner. Women experience more food-related conflict than men do, in that they like fattening foods but perceive that they should not eat them. Pressures to be thin are present in early adolescence, as noted by dieting behavior starting in very young girls. Women experience more dissatisfaction with their body weight and shape than men do. Sociocultural and psychological factors may be important in the etiology of eating disorders, which are much more prevalent in females than in males. Thus, further studies of gender differences in eating behavior will be important for understanding the etiology of eating and body-weight disorders and for designing gender-appropriate treatments.     

Charting new territory: Body esteem, weight satisfaction, depression, and self-esteem among chinese males and females in Hong Kong

This study examined the relationship of body esteem, weight satisfaction, self esteem, and depression among 309 (186 females and 123 males) Chinese university students in Hong Kong. Females were found to have significantly lower body esteem [Body Esteem Scale: S. L. Franzoi and S. A. Shields (1984) “The Body Esteem Scale: Multidimensional Structure and Sex Differences in a College Population,” Journal of Personality Assessment, Vol. 48, pp. 173–178] and higher depression [Center for Epidemiologic Studies Depression Scale: L. S. Radloff (1977) “The CES-D scale: A Self-Report Depression Scale for Research in the General Population,” Applied Psychological Measures, Vol. 2, pp. 385–401] when compared to males, whereas males were found to have significantly more weight dissatisfaction. No significant difference was found in the area of self-esteem [Index of Self-Esteem: W. W. Hudson (1982) Clinical Measurement Package: A Field Manual, Chicago: Dorsey]. Females desired a significantly lower ideal body mass index, whereas, males desired a significantly higher ideal body mass index. The relationship between body esteem, weight satisfaction, and self-esteem was similar for males and females; however, the relationship between body satisfaction and depression was significant only for females. Findings are compared to similar research on European American samples and implications from a cross-cultural perspective are discussed.     

MOOD FLUCTUATIONS

Mood fluctuations in women and men were studied both prospectively and retrospectively to determine whether cyclic changes occur over phases of the menstrual cycle, lunar cycle, and/or days of the week. The participants (15 women using oral contraceptives, 12 normally cycling women, and 15 men), who did not know the purpose of the study, recorded the pleasantness, arousal, and stability of their moods daily for 70 days (concurrent data). Later they recalled (retrospective data) their average mood for each day of the week and phase of the menstrual cycle (women only). The only evidence of mood fluctuation over the menstrual cycle in the concurrent reports was that normally cycling women reported more pleasant moods in the follicular and menstrual phase than did men and women on oral contraceptives. Women's moods fluctuated less over the menstrual cycle than over days of the week. Recollections of menstrual mood changes differed from actual changes: Women recalled more pleasant moods in the follicular phase and more unpleasant moods in the premenstrual and menstrual phases than they had reported concurrently. Bias also was evident in recollections of weekday mood fluctuations: Weekend highs were exaggerated and Monday blues were reported even though they were not reported concurrently. There was no evidence of mood fluctuations over the lunar cycle and the groups did not differ in mood stability. The retrospective reporting bias for both the mensural cycle and days of week suggests the influence of stereotypes about moods. Implications for research and practice are discussed.     

Changes in Behaviour and Body Weight Following a Single or Double Social Defeat in Rats

In a series of experiments, the consequences of a single and double social conflict on various behaviours and body weight in rats were studied. Animals were subjected to social defeat by placing them into the territory of an aggressive male conspecific for one hour, either once, or twice at the same time on two consecutive days. To assess the consequences of social defeat, three experiments were performed with independent groups of rats. In the first experiment, an open field test was performed two days after the last conflict. Locomotor activity was strongly reduced after social defeat. There were no differences between the single and double defeat group. To assess the effects of social defeat on subsequent social behaviour, a second experiment was performed in which experimental animals were confronted with an unfamiliar non-aggressive rat two days after a single or double conflict. Social defeat resulted in a reduction of social contact with the unfamiliar conspecific. There was no difference between the single and double conflict group. In the third experiment, the effects of social conflict on food intake, body weight and saccharine preference were measured. Food intake was not affected after a single conflict, but in the double conflict group food intake was decreased for several days. Body weight gain was decreased after both single and double social defeat. The decrease was stronger in the double conflict group. Water intake and saccharine preference were not significantly affected. This study revealed that social defeat in rats causes pronounced changes in various behaviours and body weight. Different aspects of behaviour are differentially affected by defeat with respect to the magnitude and time course of the changes induced. Moreover, different behavioural parameters are differentially sensitive to repetition of the stressor.     

Female sexual orientation and menstrual influences on person perception

Heterosexual women have previously been shown to display enhanced sensitivity to information that is both reproductively- and sexually-relevant (e.g., sexually mature male faces) during phases of high fertility. In the present study, homosexual women who maintained a regular menstrual cycle and did not use hormonal contraceptives completed a sex-categorization task at periods of high and low fertility within their menstrual cycle. For homosexual women there is a separation between reproductively-relevant (i.e., sexually mature males) and sexually-relevant (i.e., sexually mature females) targets. Our participants showed enhanced sensitivity to sexually-relevant information (i.e., female faces) at high fertility but showed no fluctuation in sensitivity to reproductively-relevant information (i.e., male faces) across testing sessions. These findings are considered in terms of adaptive person perception and the impact of sexual desire on mate preferences.     

Body dissatisfaction,engagement in body change behaviors and sociocultural influences on body image among Chinese adolescents

Body dissatisfaction and body image disorders are becoming increasingly prevalent in developing non-Western countries such as China, but there is a lack of research examining the sociocultural factors that in other contexts have been associated with these problems. The current study investigated body dissatisfaction, engagement in body change behaviors, and sociocultural pressures on body image, and the relationships between these variables among 517 adolescent males (N = 219) and females (N = 298) in China. Females reported greater body dissatisfaction than males, and males reported using strategies to increase their muscle bulk more often than females. Males reported pressure from a variety of sociocultural sources to increase their muscles or weight, while females reported pressure from the media to lose weight. For males body dissatisfaction was predicted by pressure from peers to increase their muscle bulk, while for females pressure to lose weight from peers, adult relatives, and the media was likely to increase body dissatisfaction. Pressure from the media and adult relatives was also predictive of body change behaviors in both males and females. The findings are discussed in relation to previous research in both Western and non-Western contexts.     

Body Image Concerns and Contingent Self-Esteem in Male and Female College Students

Body dissatisfaction in females, and to a lesser extent males, is associated with low self-esteem, depression, and eating disorders. This research examined gender as a moderator of the association between contingent self-esteem and body image concerns, including weight and muscularity. Participants included 359 (59.1% female) heavy drinking first-year U.S. undergraduate students who completed a survey assessing health-related risk behaviors. Hierarchical multiple regression was used to examine relations among gender, contingent self-esteem, and body image. Females reported higher levels of contingent self-esteem and greater concerns about their weight, although males reported a greater drive for muscularity. The relationship between contingent self-esteem and weight concerns was stronger among females, and for males, greater contingent self-esteem was associated with a greater drive for muscularity.     

Menstrual Reactivity: The Role of Gender-Specificity,Anxiety Sensitivity,and Somatic Concerns in Self-Reported Menstrual Distress

To determine the impact of gender roles, anxiety sensitivity, and somatic concerns on self-reported menstrual distress, two studies were conducted. In the first study using 278 primarily Caucasian college females, anxiety-sensitivity level, not current menstrual cycle phase, influenced reports of menstrual symptom severity and depression. Regardless of cycle phase at the time of self-report, women high in anxiety sensitivity reported significantly more depressed mood, trait anxiety, and retrospective menstrual symptoms. In the second study of 158 primarily Caucasian college females varying in anxiety sensitivity levels, adherence to sex role stereotypes, feminist beliefs, and illness attitudes were examined. Participants also completed measures of general premenstrual, most-recent premenstrual, and current menstrual symptoms. Women high in anxiety sensitivity reported the highest levels of sex-specificity, feminist embeddedness, and illness attitudes, with sex-specificity accounting for significant variance in current menstrual symptoms. Results are discussed within the context of the menstrual reactivity hypothesis, which proposes that beliefs surrounding the menstrual cycle and body sensations expectancies contribute to self-reports of greater menstrual distress. Women high in anxiety sensitivity appear to represent one subgroup vulnerable to menstrual reactivity.     

Gender dimorphic effects of voluntary running in laboratory rats depends on maturational status

This study examined the effect of 24 hr per day wheel access on running, body weight, and food intake for 30- or 50-day-old male and female rats under ad lib feeding conditions. Food intake and body weight were also monitored in a control group housed without access to running wheels. A dimorphic effect was observed after wheel introduction in 50-day-old but not 30-day-old rats: A temporary decline in food intake and a lasting decrease in body weight occurred for active male rats in comparison to their sedentary controls, and wheel access facilitated food intake and preserved body weight gain in female rats in comparison to their sedentary counterparts. Hyperphagia in adult females is interpreted in terms of the evolutionary acquired advantage linked to their reproductive function.     

Gender dimorphic effects of voluntary running in laboratory rats depends on maturational status

This study examined the effect of 24?hr per day wheel access on running, body weight, and food intake for 30- or 50-day-old male and female rats under ad lib feeding conditions. Food intake and body weight were also monitored in a control group housed without access to running wheels. A dimorphic effect was observed after wheel introduction in 50-day-old but not 30-day-old rats: A temporary decline in food intake and a lasting decrease in body weight occurred for active male rats in comparison to their sedentary controls, and wheel access facilitated food intake and preserved body weight gain in female rats in comparison to their sedentary counterparts. Hyperphagia in adult females is interpreted in terms of the evolutionary acquired advantage linked to their reproductive function.     

Effects of the menstrual cycle on vibrotactile sensitivity

Psychophysical thresholds for the detection of vibration delivered to the thenar eminence of the right hands of young males and females were measured every other day for 30–34 days. The frequency of the vibratory stimulus was either 15 or 250 Hz. The sinusoidal stimuli applied through a 3.0-cm² contactor were 700 msec in duration and had rise-fall times of 25 msec. Stimulus amplitude was measured with a calibrated accelerometer mounted on the moving element of the vibrator. Data were plotted as a function of successive days in the menstrual cycle. Thresholds for detecting the 15-Hz stimulus did not change significantly, whereas thresholds for detecting the 250-Hz stimulus varied significantly over the menstrual cycle. The 250-Hz threshold became progressively lower as subjects approached the onset of menstruation. After the onset of menstruation, the 250-Hz threshold gradually increased, reaching a maximum value approximately 12 or 13 days later. Soon after the 12th or 13th day of the cycle, the threshold again began to decline and continued to decline until the onset of the next menstrual cycle. The thresholds of women taking birth control pills did not change systematically over the testing period.     

Stereotypes and steroids: using a psychobiosocial model to understand cognitive sex differences

To further our understanding of cognitive sex differences, we studied the relationship between menstrual phase (via serum estradiol and progesterone levels) and cognitive abilities and cognitive performance in a sample of medical students in eastern Turkey. As expected, we found no sex differences on the Cattell "Culture Fair Intelligence Test" (a figural reasoning test), with females scoring significantly higher on a Turkish version of the Finding A's Test (rapid word knowledge) and males scoring significantly higher on a paper-and-pencil mental rotation test. The women showed a slight enhancement on the Finding A's Test and a slight decrement in Cattell scores during the preovulatory phase of their cycle that (probably) coincided with a rise in estrogen. There were also small cycle-related enhancements in performance for these women on the mental rotation test that may reflect cyclical increases in estrogen and progesterone. Additional analyses showed an inverted U-shaped function in level of estradiol and the Cattell Test. Finally, for women who were tested on Day 10 of their menstrual cycle, there was a negative linear relationship between their Cattell scores and level of progesterone. Stereotypes about the cognitive abilities of males and females did not correspond to performance on the mental rotation or Finding A's Test, so the sex-typical results could not be attributed to either stereotype threat or stereotype activation. For practical purposes, hormone-related effects were generally small. Variations over the menstrual cycle do not provide evidence for a "smarter" sex, but they do further our understanding of steroidal action on human cognitive performance.     

经前期综合征与奖赏进程失调——来自脑电的证据

研究表明, 经前期综合征(Premenstrual syndromes, PMS)女性的情绪平衡性存在问题, 而现有研究多从负性情绪上升的角度考察PMS的发病机制, 而对其正性情绪缺损的关注不足。鉴于正性情绪与奖赏进程密切相关, 本研究试图从奖赏进程失调的角度考察PMS女性与健康女性的差异以及该差异是否存在阶段特异性的问题, 以期从正性情绪缺损的角度揭示其发病机制。具体而言, 分别选取PMS女性与健康女性23名和22名, 考察两组被试在黄体晚期(即经前期)和卵泡早期(即经后期)正性情绪以及完成赌博任务时的脑电数据时域和频域的差异。主观问卷结果显示, PMS女性的愉快和平静情绪低于健康女性, 并且情绪平衡性也低于健康女性, 但无明显的阶段特异性。时域分析结果显示, PMS组在经前期收到奖赏反馈后奖赏正波(reward positivity, RewP)的波幅和差异波(即奖赏条件和惩罚条件下的差值)的波幅均低于健康女性, 进一步的相关分析结果显示, 对于PMS组来说, 经前期奖赏条件下的RewP波幅和差异波波幅与经前期的情绪平衡性显著正相关。频域分析的结果则发现PMS组在经前期奖赏条件下的θ频段(4~7 Hz, 250~400 ms)能量低于健康组。研究表明, PMS女性在经前期的奖赏加工进程存在异常, 表现为对奖赏反馈的预期增强, 而在收到奖赏反馈后又出现了钝化反应, 且奖赏进程的失调与情绪平衡性相关。本研究为理解PMS女性奖赏进程失调的动态加工时程和神经震荡特征及其与情绪平衡性的关系提供了初步的神经生理证据。