Open-field nidus and pullusindices in Mus Musculus L.

Swiss albino mice ( Mus Musculus L. ) were studied in an open field (OF). The question whether laboratory rodents were more attracted to a nest equipped with familiar odoriferous cues from the home-cage bedding or to signals of an unfamiliar newborn pup inserted in the OF was addressed. The results of the three quantitatively recorded OF behaviors, ambulation, retrieval and radial latency , indicated that in females both ambulation and retrieval were enhanced by the presence of a pup in a nestless field; in males locomotion was suppressed by a nest in a pupless OF. In the case of both sexes radial latency was determined by the OF position of a nest. A comparison between the two qualitative assessments, the nidus and pullus indices, yielded that the sex of the adult and the OF positions of both targets equally impacted attraction towards both nest and pup.     

Conspecific aggression in the laboratory rat.

Attacks by dominant colony males of a domesticated rat strain on conspecific strangers introduced into the colony include both a full range of threat displays and actual biting attack. These dominant males attack and bite both anesthetized and unanesthetized strangers, but threat displays and bites to anesthetized rats are limited. Lesions resulting from these bites are nonrandomly distributed, with most damage to the head and upper back and very few bites to ventral surfaces. When introduced strangers were left in the colonies for several days, 66% were killed, indicating that domesticated rats are capable of lethal attacks on conspecifics without external provocation.     

Effects of voluntary wheel running on heart rate, body temperature, and locomotor activity in response to acute and repeated stressor exposures in rats

Stress often negatively impacts physical and mental health but it has been suggested that voluntary physical activity may benefit health by reducing some of the effects of stress. The present experiments tested whether voluntary exercise can reduce heart rate, core body temperature and locomotor activity responses to acute (novelty or loud noise) or repeated stress (loud noise). After 6 weeks of running-wheel access, rats exposed to a novel environment had reduced heart rate, core body temperature, and locomotor activity responses compared to rats housed under sedentary conditions. In contrast, none of these measures were different between exercised and sedentary rats following acute 30-min noise exposures, at either 85 or 98 dB. Following 10 weeks of running-wheel access, both groups displayed significant habituation of all these responses to 10 consecutive daily 30-min presentations of 98 dB noise stress. However, the extent of habituation of all three responses was significantly enhanced in exercised compared to sedentary animals on the last exposure to noise. These results suggest that in physically active animals, under some conditions, acute responses to stress exposure may be reduced, and response habituation to repeated stress may be enhanced, which ultimately may reduce the negative and cumulative impact of stress.     

Role of estrogens in androgen-induced spontaneous activity in male rats.

Three experiments tested the hypothesis that testosterone may be aromatized to an estrogen to stimulate running-wheel activity in rats. Aromatizable (testosterone propionate: TP) and nonaromatizable (dihydrotestosterone propionate; DHTP) androgens were compared with estradiol benzoate (EB) for the ability to induce running in castrated male rats. The DHTP had no effect on running. The TP increased running, but EB was more than 100 times as effective. A relatively small dose of a specific estrogen antagonist, MER-25, was shown to attenuate the effects of both EB and TP on male running. The MER-25 did not affect the running of castrated, oil-treated male rats and did not inhibit the running induced by food deprivation.     

Gender differences in depression in college students

Although there is much evidence indicating that females report more depressive symptoms on the Beck Depression Inventory (BDI) relative to males, virtually no research has examined or reported gender differences on several other measures tapping negative affect—namely, the Expanded Attributional Styles Questionnaire (EASQ) and the Selves Questionnaire. Our first study examined gender differences on both the BDI and EASQ, and found that females reported more depressive symptoms and a more maladaptive attributional style than males. In our second study, the data revealed that, again, females were found to have a more maladaptive attributional style than males. In addition, on the Selves Questionnaire, there was a significant discrepancy between actual and ideal self for females, but not for males. When delineating most frequently used ideal categories, the data revealed that females were more likely than males to report greater strivings for ideal attributes relevant to interpersonal relationships and body image/attractiveness, whereas males reported more ideal strivings for intelligence. These data suggest some content areas in which females and males differ with regard to “traits” to which they aspire, and which may produce dejection and negative affect if not attained.     

Prepartum and postpartum open-field behavior and maternal responsiveness in mice bidirectionally selected for open-field thigmotaxis

The authors examined pre- and postpartum open-field (OF) behavior and maternal responsiveness in mice that they bidirectionally selected for OF thigmotaxis. The authors tested 40 female mice under 3 conditions: prepartum OF, postpartum OF, and a pup retrieval test. In both OF conditions, the high OF thigmotaxis (HOFT) mice were more thigmotactic but explored and reared less than the low OF thigmotaxis (LOFT) mice, indicating that the HOFT mice were more emotional. In the postpartum condition, the HOFT mothers also defecated more and ambulated less than the LOFT mothers. The increase in grooming after parturition was more conspicuous among the LOFT mothers than among the HOFT mothers. The LOFT mothers were also more attracted to their pups in the OF, but the retrieval test did not show any substantial line differences. The results suggested that the line difference in emotionality was more pronounced during lactation than during pregnancy, although parturition exerted no effect on thigmotaxis.     

Learning effects on sperm competition and reproductive fitness

Learning and other common psychological processes presumably evolved because they contribute to reproductive fitness, but reproductive outcomes are rarely measured in psychology experiments. We examined the effects of Pavlovian conditioning on reproductive fitness in a sperm-competition situation. Typically, two males mating with the same female in immediate succession sire similar numbers of offspring. In a study with domesticated quail (Coturnix japonica), we increased paternity success by presenting a Pavlovian signal that permitted one of two competing males to predict copulatory opportunity. Using microsatellite-based DNA fingerprinting, we found that signaled males sired 72% of the offspring when competing with control males, and this effect was independent of copulation order. In the absence of Pavlovian conditioning, rates of fertilization were not significantly different for two males that copulated with the same female. These findings demonstrate that Pavlovian conditioning contributes to reproductive fitness and suggest that individual past experience can bias genetic transmission and the evolutionary changes that result from sexual competition.     

Activity measures in stress-attenuated novelty tests as possible analogues for extraversion in rats: Some experimental results

In an attempt to extend and validate Garcia-Sevilla's (1974) hypothesis proposing ambulation in a non-stressful open field (OF) as an animal analogue of human extraversion, ambulatory behaviour and rearing behaviour were studied and compared in several experiments with genetically-unselected rats. The effects of variation of OF auditory stimulation level, the correlation with a two-way avoidance-learning situation and the effects of a stimulant dose of d-amphetamine and an anxiolytic one of diazepam upon rearing and ambulatory behaviours were studied. All in all, our results support some of the requirements of the hypothesis, but also generate some additional problems. The results show that the number of rearings could be a better and more sensitive measure of variations in the level of arousal and a better predictor of shuttle-avoidance conditioning than ambulation. However, all activity measures are at least moderately intercorrelated, and they become grouped when results are factor analysed. All the results are discussed with reference to Eysenck's personality theory and Gray's anxiety theory, and it is concluded that these measures are too multidetermined and too poorly controlled to represent correctly and in a direct form a personality dimension such as Extraversion. Anyway, this attempt could be a good point of departure for discovering more efficient animal behavioural measures of arousability.     

Prelordotic behavior in the hamster: a hormonally modulated transition from aggression to sexual receptivity

The behavioral responses of the female golden hamster to a sexually experienced male were analyzed as a function of the stage of the female's estrous cycle. Exogenous estradiol or estradiol followed by progesterone was given to ovariectomized females to determine the role of these hormones in the regulation of cyclic changes in the female's response to the male. Females were paired on a daily basis with sexually active males for 10 min, and behavioral interactions were recorded. Significantly more fighting occurred during early diestrus than later in the cycle. During the 24 hr preceding sexual receptivity, fighting was infrequent. BY 8 HR PRIOR TO THE ONSET OF SEXUAL RECEPTIVITY, 86% OF THE POPULATION EXHIBITED A BEHAVIOR RESEMBLING THE ONSET OF LORDOSIS WITHOUT IMMOBILIZATION (PRELORDOSIS). Following ovariectomy fighting was at a high level (80%--90%). Estradiol replacement, over a 28-day test period, resulted in a significant decrease in aggression and a significant increase in the display of the prelordotic response without inducing lordosis. Initially, the treatment with progesterone following 7 days of estradiol treatment caused the female to display lordosis. After 24 hr a significant increase in aggression, which continued as long as progesterone was present, was observed. After removal of progesterone a significant decrease in aggression occurred. Thus, estradiol causes the female to become tolerant of the male's approach, the female exhibiting prelordosis in response to the male's investigation. Estradiol and progesterone are necessary for normal sexual receptivity; however, after 24 hr, estrogen-progesterone-treated females become agonistic to the male.     

Expressed vocational choices and later employment compared with Vocational Preference Inventory and Kuder Preference Record-Vocational scores

Expressed vocational choices were more predictive of employment status four years after high school graduation for males than were scores on either the Vocational Preference Inventory or the Kuder Preference Record-Vocational. The Vocational Preference Inventory and expressed choices were about equally efficient in predicting future employment for females. The Kuder Preference Record-Vocational was far less predictive of future employment than the other measures employed in the study. Predictions for males were more accurate than for females on all measures.     

Risk perception in novice drivers: the relationship between questionnaire measures and response latency

The extent to which questionnaire based measures of driving risk, driving ability and accident likelihood are associated with response latency based measures obtained on a hazard perception test was examined. In Experiment 1 questionnaire evaluations of driving in general were obtained and correlated with hazard perception performance. In Experiment 2 questionnaire evaluations and hazard perception performance were obtained when drivers viewed the same driving scenes. In neither experiment did questionnaire responses correlate significantly with hazard perception performance. Additionally while in both experiments no difference in hazard perception performance arose between males and females, females rated driving as more risky and their ability to be lower than males. The results indicate independence between questionnaire and response latency measures of hazard perception. However the possibility that both approaches should be adopted within a single framework is raised.     

Body Satisfaction in Gym-active Males: An Exploration of Sexuality, Gender, and Narcissism

This study compared 80 gay and straight Australian males on self report measures of body satisfaction, masculinity, femininity, narcissism, and reasons for exercising at gyms to explore factors related to excessive exercise. Gay males are less satisfied with their bodies compared to straight males. Improving appearance was more important for gay men, while fun was considered more important for straight men. Only sexual orientation and masculinity contributed independently to body satisfaction. Straight males who scored high on masculinity were most satisfied with their bodies, while gay males who scored low on masculinity were least satisfied with their bodies, irrespective of femininity and narcissism. Hours exercising per week and fun as a reason for exercising, significantly contributed to body satisfaction.     

More alike than meets the eye: Perceived gender differences in subjective experience and its display

This research investigated perceived gender differences in subjective experience and its outward display. Subjects imagined a female friend or a male friend in a series of brief situations, each of which was said to elicit a particular subjective experience in the friend. After each situation, they estimated the extent to which the friend would experience the feeling, and also the extent to which the friend would display the feeling to others. Results confirmed two related predictions, both based on attribution research: First, perceived gender-related differences in the outward display of an experience were generally greater than perceived gender-related differences in the subjective experience itself. Males and females, that is, were generally viewed as more alike in their internal feelings than in their overt behaviors. Second, perceived female/male differences in outward display varied more with the feeling elicited by the situation than perceived female/male differences in subjective experience. Specifically, subjects estimated that females would display communal, socially desirable feelings more than males and self-oriented, less desirable feelings less than males, but that females would experience both categories of feelings somewhat more intensely than males would experience them. In addition to confirming these two predictions, our results also indicated that the sex viewed as having greater hidden feelings—operationalized as the amount by which estimations of subjective experience exceeded estimations of display—also varied with the situation. With communal, highly desirable feelings, males were viewed as having greater hidden feelings, but with self-oriented, less desirable feelings, females were viewed as having greater hidden feelings. This pattern did not interact with gender of perceiver. The data, however, indicated that female perceivers tended to rate both males and females higher on measures of both experience and display than males did, and that male perceivers tended to perceive greater gender differences than females did.     

The development of classificatory skills and sex-trait stereotypes in children

The development of knowledge of sex-trait stereotypes was related to changes in classification skills during childhood. Children of 4, 6, and 8 years of age were tested for knowledge of sex-trait stereotypes on the Williams, Bennett, and Best measure; ability to reclassify sex-traits; and on measures of consistent sorting and reclassification. Knowledge of sex-trait stereotypes improved with age and with performance on the consistent sorting task. Subjects who were able to recognize that sex traits are manifested by persons of both genders were older and more likely to pass measures of nonsocial reclassification. Claims that some males manifest feminine behavior did not change with age. The findings suggest that at first, traits are classified as stereotypical of a gender category; but with increasing cognitive level, these traits become less stereotypical of gender.This study was supported by National Institute of Mental Health Grant MH 29863 to Robert Leahy. The authors wish to acknowledge the assistance of Jill Bresler in the collection and scoring of data.     

Cigarette smoking intentions and physical fitness: a multivariate study of high school males

This study was conducted to determine the extent to which several measures of physical fitness, treated compositely and individually, vary among adolescent males differentiated according to cigarette smoking status (i.e., strong intenders, mild intenders, and nonintenders). A total of 381 high school males were administered The Physical Performance Test for California to measure six traits of physical fitness, and a written questionnaire to assess smoking intentions and demographic data. As hypothesized, the teenage males who reported no intentions of smoking cigarettes were significantly more physically fit than were mild intenders and strong intenders, especially the latter. Etiological factors mediating the association are discussed within an underlying theme of prevention and cessation of the habit.     

Effects of the heterosomes and maternal environments on aggressive behavior in Mus musculus

This is a study of the offense type of aggression in males of the DBA/1Bg and C57BL/10Bg inbred strains of mice and their two reciprocal F1 hybrids. It uses three test paradigms for dyadic encounters: the homogeneous set test, an identity panel of testers, and the standard opponent test. There were no reciprocal F1 hybrid differences for any of the 12 behavioral measures of aggression in the homogeneous set test or the standard opponent test. For the panel of testers paradigm, reciprocal F1 hybrid differences occurred when the tester (opponent) was an F1 hybrid male, but not when the tester (opponent) was an RB/1 or C57BL10 male. When B10RB1F1 males were the testers (opponents), B10RB1F1 hybrid males were more aggressive than RB1B10F1 hybrid males across 10 of the 12 behavioral measures. Conversely, when RB1B10F1 males were the testers (opponents), RB1B10F1 males were more aggressive than B10RB1F1 males across 9 of the 12 behavioral measures. These results conform to the following empirical rule: A significant difference between reciprocal F1 hybrids is observed for these behavioral measures when one of the hybrids has both of its heterosomes (X and Y chromosomes) and its maternal environment identical to those of its opponent and the other hybrid has none of these identical to those of its opponent. These results are consistent with a model in which on some genetic backgrounds, but not on others, similarity of the heterosomes and maternal environments can influence the display of or response to social or other stimuli for the offense type of aggression in mice. These stimuli may be individual recognition chemosignals in urine.     

Running-wheel activity and avoidance in the mongolian gerbil

In the first of two experiments, running-wheel activity and unsignaled (Sidman) avoidance were studied in gerbils and albino rats. All gerbils ran at higher rates than any of the four rats studied. Under the avoidance procedure, four rats developed effective responding; the other two performed much less successfully. While avoidance developed more slowly in the gerbils, all showed asymptotic performance as effective as the four superior rats. The rats showed a consistent warm-up effect, receiving 60% to 80% of the total shocks in the initial third of the session. The gerbils displayed no warm-up, with shocks being evenly distributed over the session. Warm-up in the rats was not related to either response rate or to how effectively the animal was avoiding. When shock was removed, extinction occurred more rapidly in the rats than the gerbils. In the second experiment, which involved two-way shuttle avoidance, gerbils and albino mice quickly acquired the response. All animals met a criterion of 90% avoidance over 80 trials.     

Functional cerebral asymmetry in hostility: a dual task approach with fluency and cardiovascular regulation

The influence of hostility levels on verbal and nonverbal fluency, and the concurrent cerebral regulation of autonomic nervous system functioning was examined in 48 right-handed males, half classified as low-hostile, and half as high-hostile. Recent research has supported inhibitory roles for the anterior right cerebrum in sympathetic regulation, and the anterior left cerebrum in parasympathetic regulation. Two neuropsychological tests purportedly mediated by left and right anterior cerebral systems, respectively, are the Controlled Oral Word Association Test and the Ruff Figural Fluency Test. Fluency and perseverative errors were assessed using these measures. Systolic and diastolic blood pressure, and heart rate were assessed with a digital blood pressure meter. It was predicted that high-hostile men would evidence interference on cardiovascular regulation concurrent with the nonverbal fluency task in comparison to low-hostile males. Further, interference was expected to manifest in the cognitive variable with more perseverative errors on the nonverbal fluency task in high-hostile males than in low-hostile males. The results support a capacity-limited prediction. High-hostile males evidenced significantly heightened systolic blood pressure during the nonverbal fluency task in comparison with low-hostile males. Further, high-hostile males displayed more perseverative errors in nonverbal fluency than did the low-hostile males. These results support the expectation that differences exist between high- and low-hostile males for right frontal functioning. These findings were discussed within the proposed anterior-posterior inhibition model of hostility.