Role of female behavior in controlling population growth in mice

Sex ratio does not appear to be a factor in generating the characteristic population growth curve. Freely growing populations of house mice, consisting of all females and one male, stopped their growth at approximately the same densities as normal sexratio populations used as references. The mechanism(s) of female control of population dynamics may be related to female aggressive behavior. As the all-female/one-male populations approached their maximum size, the females began to show wounding patterns and social hierarchies in much the same manner as males in populations with normal sex ratios. The male in each of the populations was severely wounded in the posterior region, and each lost its tail as a result of injuries which could have been inflicted only by the females. The female social hierarchy can be seen only when there has been reproduction and population growth. Assembled populations of all females rarely exhibit aggressive behavior. Female aggression becomes apparent only when the population approaches its maximum size and thereafter. These data are consistent with the hypothesis that males are competitive among themselves for territory and social rank, and ultimately to mate with the females. Other investigators have indicated that females respond to population size, which may reflect increased competition between the females with the establishment of territories. Thus female agression may control population growth, a role previously ascribed to male aggression.     

Reciprocal effects of motivation in physical education and self-reported physical activity

ObjectivesThe present study tested whether self-reported school and leisure-time physical activity have a reciprocal relationship with Physical Education (PE)-based motivational regulations described by self-determination theory. Participants were 635 11- and 12-year-old school children from the United Kingdom.Design & MethodA cross-lagged longitudinal design over two time points was employed. Study hypotheses were analyzed using latent factor reciprocal effects models.ResultsFollowing temporal invariance tests, data revealed positive relationships between both types of physical activity and subsequent changes in autonomous motivation, but not the oft-stated reverse relationship. No relationships were observed involving introjected regulation. Theoretically aligned relationships between external regulation and changes in physical activity were observed, but no reverse relationships. Both types of physical activity behavior were negatively associated with changes in amotivation in PE, but surprisingly, amotivation in PE positively predicted changes in leisure-time physical activity.ConclusionsIn general, physical activity participation may help children internalize reasons for partaking in PE and foster self-determination. However, the widespread theory that self-determined PE motives can develop school and leisure-time physical activity participation was not compellingly demonstrated.     

"Intentional physical injury" in grand mal seizure

An account of an unusual occurrence during a grand mal epileptic fit occurring during a sexual act (labium pudendi bite = "willful bodily harm").     

Context effects on the perceived physical attractiveness of faces

Four experiments were conducted to study the nature of context effects on the perceived physical attractiveness of faces. In Experiment 1, photos of faces scaled on attractiveness were presented in sets of three, with target faces appearing in the middle flanked by two context faces. The target faces were of average attractiveness, with the context faces being either high, average, or low in attractiveness. The effect of the context was one of assimilation, rather than contrast, regardless of whether the persons in the photos were portrayed to be associated. This result was interpreted in terms of a “generalized halo effect” for judgments of the physical attractiveness of stimuli within a group. Presenting the persons of a set as friends enhanced the perceived attractiveness of the target face but only when the context did not contain a face of low attractiveness. In Experiment 2, the assimilation effect was observed to carry over to influence ratings of the target faces several minutes after the context faces had been removed. Experiment 3 showed the assimilation effect to be robust regardless of whether the context was composed of two faces or one, but Experiment 4 showed the assimilation effect to be evident only when the context faces were presented simultaneously with the target.     

Emotional effect of physical aggression among adults in the general population in a Canadian province

The emotional effect of personal involvement in physical aggression was examined in a random sample of 1,753 adults from Ontario, Canada, using Computer Assisted Telephone Interviewing (response rate of 67%). Respondents reported a range of emotional responses from feeling good or justified to feeling angry, upset, terrified, disgusted, hurt, and embarrassed. Open-ended responses regarding emotional response were rated by the authors for 149 incidents of aggression, which yielded five categories: (1) positive impact 4%, (2) no feeling or no effect 31%, (3) mildly negative 20%, (4) moderately negative 28%, and (5) severely negative 17% (Kappa statistic of interrater agreement=.77). The substantial proportion of incidents involving positive or no emotional response suggests that a greater understanding of aggression among individuals can be gained by the development and application of a quantitative measure of emotional response that reflects the full range of emotions (positive and negative), using dimensions identified in this study such as feeling upset, fear, and anger.     

An exploration of psychological and physical injury schemas in civil cases

Civil plaintiffs often seek compensation for their psychological injuries. Yet little is known about jurors' preconceived notions (or schemas) for a prospective plaintiff's pain and suffering. The present studies examined (a) whether jurors have psychological injury schemas (Studies 1 and 2), (b) whether their existence and development vary by the type of civil case (Studies 1 and 2) or its severity (Study 2), and (c) how psychological injury schemas compare with physical injury schemas on a number of theoretically and legally relevant judgments (e.g., injury severity, availability, and plaintiff credibility; Study 2). Study 1 (N = 233) presented undergraduate mock jurors with 2 negligence incidents (car accident and slip and fall) and 2 intentional tort incidents (sexual assault and kidnapping) and asked them to report the typical incident and injuries that would result from the defendant's conduct. Results supported the sparse existence of psychological injury schemas but found that they were more developed in the kidnapping and sexual assault incidents than in the car accident and slip and fall incidents. Study 2 (N = 288) additionally manipulated incident schema severity (mild vs. severe) while having participants separately report and rate their psychological and physical injury schemas on judgments of legal and theoretical interest. Results indicated that although mock jurors' psychological injury schemas contained fewer injuries than their physical injury schemas, the reported psychological injuries were rated as more severe than physical injuries. We discuss how schemas may underlie the disparate treatment of psychological and physical injuries by legal decision‐makers.     

Prevalence of traumatic brain injury in an inpatient psychiatric population

This study investigated the prevalence of traumatic brain injury (TBI) in an inpatient psychiatric population. We hypothesized increased prevalence of TBI relative to the general population due to a variety of risk factors observed in psychiatric patients. One hundred (mean age = 34) psychiatric inpatients completed the revised Head Injury Questionnaire. Chart review of 17 subjects reporting injuries established whether injuries were documented in medical records. Sixty-eight percent of this psychiatric population reported one or more injuries in which they were unconscious or dazed. This number is higher than the prevalence in the general population. Injuries were generally of mild to moderate severity; multiple injuries were common. Chart review of 17 subjects reporting TBI indicated that histories of TBI had not been noted in the medical record. Finally, 63% of TBI subjects reported that their injury predated the onset of their psychiatric symptoms. These results suggest a possible role of TBI in psychiatric symptomatology and have implications for psychiatric treatment in this population.     

Tau and Kappa effects in physical space: the case of audition

The organization of spatio-temporal information in an auditory memory task was studied in two experiments. Stimuli consisted of four different configurations of eight sequentially presented beeps. In two configurations, the stimuli were space-time congruent, with (constant or variable) inter-stimulus distances corresponding to (constant or variable) inter-stimulus time intervals. In the other two configurations, the stimuli were space-time incongruent, with (constant or variable) inter-stimulus distances not corresponding to (variable or constant) inter-stimulus time intervals. After a learning phase consisting of 20 presentations of the target configuration, participants reproduced the spatial (Experiment 1) or temporal (Experiment 2) characteristics of the target 60 times in succession without re-examining the target configuration. Accuracy (with respect to the target) and variability (between responses) were found to evolve independently. In the incongruent space-time conditions, effects of variable inter-stimulus time intervals or distances on the reproduction of, respectively, constant distances (Tau effect) or constant time intervals (Kappa effect) were observed, while the reverse was not the case. Thus, dimensional interference occurred when the dimension to be ignored was variable. The results are discussed in the light of the distinction between properties of the stabilized mental image and the process of stabilization.     

The role of anxiety sensitivity in subjective and physiological responses to social and physical stressors

This study examined the specificity of the relationship between anxiety sensitivity (AS), a measure of catastrophizing about arousal-related sensations, and pain responses, by examining the effect of AS on responses to stressors of a physical and social nature. Healthy men and women (n = 129) between the ages of 18 and 25 years were recruited from the community to participate in a study examining subjective, cognitive and behavioural responses to different types of stressors. Participants were randomly assigned to one of 3 groups: (i) a neutral condition in which they sat quietly and read a popular magazine; (ii) a social stress condition in which they anticipated having to give a self-disclosing speech; and (iii) a physical stress condition in which they were presented with 3 countdown to shock trials where a mild electrical shock was administered on the non-dominant arm. Subjective ratings and physiological responses were recorded in anticipation of the stressor and immediately after stress exposure. Results indicated that AS was indirectly related to pain ratings via its effect on anticipatory anxiety ratings. AS was associated with anticipatory anxiety ratings, regardless of whether the stressor was of a physical or social nature. Furthermore, AS was not shown to be directly associated with exaggerated subjective or physiological reactions to the physical stressor. These results indicate that the role of AS in pain responses may be mediated through a global effect on anxiety, and limited to the anticipatory stage of the pain experience. If future studies yield similar findings in pain patients, then they would suggest that interventions for helping individuals high in AS should focus on catastrophic thinking in anticipation of stressors in general, rather than on pain-specific stressors.     

Role of chromaticity, contrast, and local orientation cues in the perception of density

We compared the role of the red-green, blue-yellow, and luminance post-receptoral mechanisms in the perception of density. The task requires the comparison of densities between two stimuli composed of oriented bandpass elements, pseudo-randomly scattered across an area of constant size. The perception of density differences was measured by a temporal 2AFC procedure for all pairs of mechanisms and for four possible densities. We found that stimuli of identical physical densities are not perceived equally: there is a consistent bias in favour of blue-yellow stimuli which are perceived as significantly more dense than red-green and achromatic stimuli. We considered three factors that could have differentially affected the density perception of blue-yellow stimuli: an increase in the perceived size of the individual blue-yellow elements, a perceived contrast difference, and the presence of local orientation cues. We found that the increased perceived density of the blue-yellow stimuli occurred despite the fact that there was no increase in perceived size of the individual elements, and remained despite corrections for the two other factors. We conclude that the significant increase in perceived density for the blue-yellow mechanism is a global effect, associated with a perceived colour 'melting' of the elements in the array. Our data were fitted with the occupancy model of Allik and Tuulmets (1991, Perception & Psychophysics 49 303-314) and we found that blue-yellow stimuli have a greater 'occupancy' than red-green or achromatic stimuli.     

Attributions of behavior in the pediatric mild closed head injury (CHI) population

Forty-one children between the ages of 6 and 11 years with a history of a mild closed head injury and 23 age-, gender-, and IQ-matched typically developing control children participated. All of the children in the CHI sample were referred for a magnetic resonance imaging (MRI) scan at 3 months post-injury and children in the CHI sample were further divided into MRI-Negative (n=31) and MRI-Positive (n=10) conditions according to the MRI results. Parents and teachers completed behavioral checklists at three points, including just prior to the MRI and 6 months post-injury. Prior to the MRI (Time 2), in both samples of children with a CHI, parents reported an increase in externalizing symptoms after the CHI. At 6 months post-injury (Time 3: post-MRI), parents of children in the MRI-Positive group did not report any significant changes in their child's externalizing behaviors when compared with pre-MRI, yet parents of children in the MRI-Negative group reported a further increase in externalizing behaviors. Parent attributions also changed as a function of group membership; whereas no changes were noted in the other two groups, parents of children in the MRI-Negative sample ascribed more controllability at Time 3 when compared with Time 2.     

The effects of marijuana on human physical aggression

Thirty male undergraduates received intense provocation following their ingestion of one of three doses of delta-9-tetrahydrocannabinol (THC). The subjects in the low-dose condition tended to respond in a more aggressive manner than the subjects in the moderate-and high-dose conditions. The subjects in the high-dose condition behaved in a relatively nonaggressive manner throughout the experimental session.     

Some fear-potentiating effects of fluprazine hydrochloride in mice

The fear-potentiating effects of fluprazine hydrochloride were explored in a series of five experiments. The drug was found to strongly inhibit entry into a novel open field, exploration of a complex maze, or approach to a novel object placed in the animal's home cage. Time sampling techniques were used to assess drug effects on frequencies of immobility, activity, and grooming and rearing responses prior to and for 70 min after footshock. There were no group differences during the 10 min immediately following shock but the groups diverged steadily in immobility, activity, and grooming for the remainder of the observations. Post-shock activity and grooming responses increased steadily towards baseline values among control mice but remained at low levels or declined among drug-treated mice. Immobility responses declined steadily among control mice but increased substantially among the fluprazine-treated mice throughout post-shock observations. Pairs of male mice treated with fluprazine were also found to maintain greater intermouse distances in a novel linear runway than pairs of undrugged adult males, juvenile males, or male-female pairs. It is suggested that fluprazine hydrochloride both potentiates fear and alters its time course in addition to interfering in some way with normal olfactory processes.     

Crowding effects of density and interpersonal distance.

In this study, Turkish teenagers were the subjects in an investigation of the effects of spatial and social variables on perceived crowding. In Study 1, male and female subjects were presented with diagrams that simulated social situations in which (a) distance between the subject and other persons, (b) number, or density, of subjects, (c) sex, and (d) friendship were systematically varied. Results indicated a significant crowding effect for interpersonal distance but not for density. In Study 2, data from Turkish college students showed that the lack of effect for density on crowding was stable. Friendship and sex of others had significant main and interaction effects.