809 resultados para AGGRESSION
Resumo:
Background We manipulated predation risk in a field experiment with the cooperatively breeding cichlid Neolamprologus pulcher by releasing no predator, a medium- or a large-sized fish predator inside underwater cages enclosing two to three natural groups. We assessed whether helpers changed their helping behaviour, and whether within-group conflict changed, depending on these treatments, testing three hypotheses: ‘pay-to-stay’ PS, ‘risk avoidance’ RA, or (future) reproductive benefits RB. We also assessed whether helper food intake was reduced under risk, because this might reduce investments in other behaviours to save energy. Methodology/Principal Findings Medium and large helpers fed less under predation risk. Despite this effect helpers invested more in territory defence, but not territory maintenance, under the risk of predation (supporting PS). Experimentally covering only the breeding shelter with sand induced more helper digging under predation risk compared to the control treatment (supporting PS). Aggression towards the introduced predator did not differ between the two predator treatments and increased with group member size and group size (supporting PS and RA). Large helpers increased their help ratio (helping effort/breeder aggression received, ‘punishment’ by the dominant pair in the group) in the predation treatments compared to the control treatment, suggesting they were more willing to PS. Medium helpers did not show such effects. Large helpers also showed a higher submission ratio (submission/ breeder aggression received) in all treatments, compared to the medium helpers (supporting PS). Conclusions/Significance We conclude that predation risk reduces helper food intake, but despite this effect, helpers were more willing to support the breeders, supporting PS. Effects of breeder punishment suggests that PS might be more important for large compared to the medium helpers. Evidence for RA was also detected. Finally, the results were inconsistent with RB.
Resumo:
Reconciliation is the occurrence of friendly behaviour between opponents shortly after an aggressive conflict. In primate groups, reconciliation reduces aggression and post-conflict arousal. Aggression within a group can also increase arousal of bystanders (e.g. increase bystanders’ rates of self-directed behaviour). Since reconciliation reduces aggression between opponents, we tested whether it also reduces self-directed behaviour in bystanders. Following aggression in a captive group of hamadryas baboons, one observer conducted a focal sample on one of the combatants to document reconciliation and a second observer simultaneously conducted a focal sample on a randomly selected bystander. Matched control observations were then collected on the same individuals in a nonaggressive context to obtain baseline levels of behaviour. The self-directed behaviour of bystanders was elevated after witnessing a fight compared to baseline levels. If combatants reconciled aggression, bystander rates of self-directed behaviour significantly decreased. If combatants did not reconcile aggression, bystander rates of self-directed behaviour remained at elevated levels, significantly higher than after reconciliation. If combatants affiliated with partners other than their original opponent, bystander rates of self-directed behaviour did not decrease. The rate of bystander self-directed behaviour after a combatant affiliated with its opponent was significantly lower than the rate after a combatant affiliated with other animals. Witnessing aggression increased arousal in bystanders, and reconciliation between the combatants was accompanied by reduced bystander arousal. The reduction was specific to contexts in which former opponents interacted. We suggest that bystanders recognized the functional significance of this conflict resolution mechanism when it occurred in their group.
Resumo:
Reconciliation is the occurrence of friendly behaviour between opponents shortly after an aggressive conflict. In primate groups, reconciliation reduces aggression and postconflict arousal. Aggression within a group can also increase arousal of bystanders (e.g. increase bystanders' rates of self-directed behaviour). Since reconciliation reduces aggression between opponents, we tested whether it also reduces self-directed behaviour in bystanders. Following aggression in a captive group of hamadryas baboons, one observer conducted a focal sample on one of the combatants to document reconciliation and a second observer simultaneously conducted a focal sample on a randomly selected bystander. Matched control observations were then collected on the same individuals in a nonaggressive context to obtain baseline levels of behaviour. The self-directed behaviour of bystanders was elevated after witnessing a fight compared to baseline levels. If combatants reconciled aggression, bystander rates of self-directed behaviour significantly decreased. If combatants did not reconcile aggression, bystander rates of self-directed behaviour remained at elevated levels, significantly higher than after reconciliation. If combatants affiliated with partners other than their original opponent, bystander rates of self-directed behaviour did not decrease. The rate of bystander self-directed behaviour after a combatant affiliated with its opponent was significantly lower than the rate after a combatant affiliated with other animals. Witnessing aggression increased arousal in bystanders, and reconciliation between the combatants was accompanied by reduced bystander arousal. The reduction was specific to contexts in which former opponents interacted. We suggest that bystanders recognized the functional significance of this conflict-resolution mechanism when it occurred in their group. (c) 2013 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
Resumo:
Primates as a taxonomic Order have the largest brains corrected for body size in the animal kingdom. These large brains have allowed primates to evolve the capacity to demonstrate advanced cognitive processes across a wide array of abilities. Nonhuman primates are particularly adept at social learning, defined as the modification of behavior by observing the actions of others. Additionally, primates often exploit resources differently depending on their social context. In this study, capuchin monkeys (Cebus apella) were tested on a cognitive task in three social contexts to determine if social context influenced their performance on the task. The three social contexts included: alone, having a dominant individual in an adjacent compartment, and having a subordinate individual in the adjacent compartment. The benefits to this design were thatthe social context was the only variable influencing performance, whereas in previous studies investigating audience effects other animals could physically and directly influence a subject's performance in an open testing situation. Based on past studies, Ipredicted that the presence of a dominant individual would reduce cognitive task performance compared to the other conditions. The cognitive test used was a match-tosample discrimination task in which animals matched combinations of eight geometric shapes. Animals were trained on this task in an isolated context until they reached a baseline level of proficiency and were then tested in the three social contexts in a random order multiple times. Two subjects (Mt and Dv) have successfully completed trials under all conditions. Results indicated that there were no significant difference in taskperformance across the three conditions (Dv x^2 (1) = 0.42, p=0.58; Mt x^2 (1) = 0.02, p=0.88). In all conditions, subjects performed significantly above chance (i.e., 39/60 trials determined by a binomial distribution). Results are contrary to previous studies thatreport low status monkeys 'play dumb' when testing in a mixed social context, possibly because other studies did not account for aggressive interference by dominants while testing. Results of this study suggest that the mere presence of a dominant individualdoes not necessarily affect performance on a cognitive task, but rather the imminence of physical aggression is the most important factor influencing testing in a social context.
Resumo:
The concept of warning behaviors offers an additional perspective in threat assessment. Warning behaviors are acts which constitute evidence of increasing or accelerating risk. They are acute, dynamic, and particularly toxic changes in patterns of behavior which may aid in structuring a professional's judgment that an individual of concern now poses a threat - whether the actual target has been identified or not. They require an operational response. A typology of eight warning behaviors for assessing the threat of intended violence is proposed: pathway, fixation, identification, novel aggression, energy burst, leakage, directly communicated threat, and last resort warning behaviors. Previous research on risk factors associated with such warning behaviors is reviewed, and examples of each warning behavior from various intended violence cases are presented, including public figure assassination, adolescent and adult mass murder, corporate celebrity stalking, and both domestic and foreign acts of terrorism. Practical applications and future research into warning behaviors are suggested. Copyright © 2011 John Wiley & Sons, Ltd.
Resumo:
Foreign bodies are common findings in the maxillofacial region, most commonly the result of accidents and physical aggression. Among the objects frequently found in the orofacial tissues are fragments of metal, plastic, wood, and glass. Visualization and exact identification of the location of these objects can be challenging but is of major importance prior to surgical removal. The present case report describes the use of cone beam computed tomography to locate, visualize, and surgically remove glass particles in the oral cavity.
Resumo:
During the last decade interest in bully/victim problems has grown tremendously and still, studies addressing this issue in the years preceding elementary school areextremely rare. Despite obvious methodological challenges, the study of bullying and victimization in settings such as kindergarten opens up unique opportunities to understand early processes in the pathways to victimization, and to investigate different social and individual risk factors and their interactions in the very beginnings of bullying patterns. In this presentation, key findings that shed light on early vulnerability factors for victimization and factors that may maintain bullying patterns will be addressed. First, results from our and others’ studies in kindergarten are generally consistent with results in school. Second, our studies show that patterns of reactions when children witness victimization are already present in kindergarten settings. Third, all findings confirm that bully-victims must be regarded as being distinct from passive victims and other aggressive children (i.e. bullies) already at kindergarten age. Our studies indicate that bully-victims have significantly more problems associated with ADHD or with a lack of behavioral regulation than all their peers and that they clearly differ from bullies in terms of the type of aggression they display. Furthermore, our longitudinal data show different pathways to victimization for victims and bully-victims. This knowledge of early risk factors and pathways mustbe taken into consideration in future research and may contribute to the improvement of prevention programs.
The contexts of scratching behavior and postconflict behavior in squirrel monkeys (Saimiri sciureus)
Resumo:
Self-directed behavior (SDB), such as scratching, is a reliable indicator of emotional arousal in non-human primates. In contrast, affiliative behavior, such as social grooming, has been shown to have a calming effect in primates and reduce arousal. In order to test whether the expression of SDB was related to arousal, the scratching behavior of eight captive squirrel monkeys (Saimiri sciureus) was compared across four social contexts (huddling, proximity to others, solitary and post-conflict). In addition,rates of scratching were examined before and after affiliative behavior during the postconflict context. I tested for this effect by using the post-conflict/matched control(PC/MC) method in which post-conflict (PC) behavior of an animal is compared to thebehavior of the same animal in a baseline, nonaggressive situation or a matched control(MC). Context and associated scratching data were obtained from a total of 98 hours of focal sample data. Scratching was significantly lower while animals were huddling thanthe other two contexts. Scratching rates while solitary were significantly higher than those occurring while animals were in proximity. Scratching was also higher in PC than MC. Following conflict, animals were significantly more likely to make contact withthird parties not involved in aggression. Most of these (79%) were a third party approaching a combatant. Further, scratching rates decreased following post-conflict third party contacts and the decrease was not due to a general decrease in scratching thatmight have been occurring after the aggressive interaction. Huddling behavior appears to reduce arousal in squirrel monkeys and may act as a tension-reduction mechanism. The elevated scratching in the solitary context may suggest that squirrel monkeys may be engaged in activities while solitary, such as vigilant behavior that may increase arousal. The third party post conflict affiliative contacts observed were the first such interactions observed in squirrel monkeys. The fact that these third contacts reduced scratching ratesin the combatants indicates that 'consolation' may have been demonstrated in this species. The overall pattern of results suggested that scratching was reliable behavioral indicator of anxiety in squirrel monkeys. These results indicate that overt behavior can be used to assess emotional states in this and other species, acting as a mediator to understanding how emotions regulate social behavior.
Resumo:
The project looked at aggressiveness in different age and social groups of modern post-totalitarian society, beginning with the hypotheses that the greatest risk groups are teenagers and the unemployed, and that there is a link between aggression and the level of meaningfulness of life. The groups studied comprised about 200 persons from urban areas of eastern Ukraine, including schoolchildren, students, white collar workers, self-employed persons, the unemployed and pensioners. Workers in industry were not included as this group has virtually disappeared in Ukraine at present since most enterprises have ceased to work and most workers have moved into the groups of the unemployed or self-employed. Participants were divided into age groups of 13-14, 16-17, 18-22, 24-45, 46-60 and over 60, with each group including approximately equal number of men and women. Research methods included Buss-Darky techniques, the "hand test" (E. Wagner), the "non-existent animal" technique, a Rozenzweig picture frustration study, purpose-in-life tests and an interview. The Buss-Darky test showed that schoolchildren have the highest level of aggression, followed by students. These groups have high indexes in virtually all types of aggression, including its open form. The self-employed have relatively lower indexes, although they are more likely to manifest it openly, while such open manifestations are less likely among white-collar workers, pensioners and the unemployed. The least aggressive were the unemployed and pensioners, although the latter had a relatively high level of hostility. In terms of age, aggression was shown to decrease with age, which Ms. Ivanova attributes to the still imperfect control mechanisms of teenagers and their less mature personalities. Among the younger groups girls showed a slightly higher level of aggression, although this situation was reversed among older people. The risk groups inclined to manifest open forms of aggressiveness can therefore be seen to be teenagers and students. Other tests used show aggressiveness as a feature of the current state, rather than as an inherent feature and the results obtained were somewhat different. In the interviews, all adults referred to the increased aggressiveness in society and most stated that they themselves had become more aggressive and bad-tempered. The ability of individuals to adapt to their social environment was also investigated and schoolchildren turned out to have the lowest adaptation index and the unemployed the highest. MS. Ivanova attributes that latter, rather surprising, result to the fact that the constant frustrations facing the unemployed force them to actively seek ways and means of adapting in order to survive. The final aspect considered was the possible connection between human aggressiveness and the meaningfulness of life. Here the groups with the most meaningful lives were the self-employed and pensioners. The latter result, again rather surprising, was attributed to the desire of people who have already lived the greater part of their lives to place more weight on what they have already done, in order to prove to themselves that they have not lived in vain. The hypothesis that aggressiveness is conversely related to the meaningfulness of life was only partially confirmed. In the two extreme cases (schoolchildren and pensioners) this was indeed the case, but the remaining groups did not show any such connection. From the data obtained, Ms. Ivanova concluded that life in modern post-totalitarian society does indeed foster a rise in people's aggressiveness, and this was supported by the fact that indexes of aggressiveness proved to be higher than the norm. Her original hypothesis as to the groups in society most at risk from open aggression confirmed in the case of teenagers but not of the unemployed, who had relatively low aggressiveness indexes and the highest degree of adaptation.
Resumo:
One of the aims of this project was to understand the way in which external environment or situation affects children's behaviour. Emotional experiences are developed and acquired under the influence of the environment, and a good family relationship is necessary for young people to grow, develop and socialise at all ages. Stress causes specific negative emotions, including concern, anxiety, sorrow and hostility. A pathologic environment in childhood forces the development of special abilities, both creative and destructive, It supports the development of an abnormal state of mind in which the usual relations between body and mind, reality and imagination, knowledge and memory are changed. Here the environment considered was that of the war and aggression in Bosnia & Herzegovina, where children, particularly those from Podrinje, witnessed arrests, killing, deforming and slaughtering of adults and children, in many cases members of their immediate families. Sehovic analysed the content of drawings by children exposed to various degrees of stress, to discover how these indicate various degrees of stress with the aim of using these as a projective technique in diagnostic work with children. The sample included around 600 children expelled from their homes, of both sexes aged between 6 and 12.
Resumo:
OBJECTIVE: To describe and evaluate psychosocial factors in nonorganic voice disorders (NVDs). Nonorganic voice disorders are presumed to be the result of increased muscular tension that is caused to varying extents by vocal misuse and emotional stress. It is therefore necessary to include both of these in the diagnosis and treatment of patients with voice disorders. DESIGN: Clinical survey. SETTING: Academic tertiary referral center. PATIENTS: To evaluate psychosocial factors in NVDs, a sample of 74 patients with NVDs was examined psychologically using the Giessen Test and Picture Frustration Test. The results were compared with a control group of 19 patients with an organic dysphonia (vocal cord paralysis). MAIN OUTCOME MEASURES: Six scales of the Giessen Test (social response, dominance, control, underlying mood, permeability, and social potency), 3 reaction types of the Picture Frustration Test (obstacle dominance, ego defense, and need persistence), and 3 aggression categories of the Picture Frustration Test (extrapunitivity, intropunitivity, and impunitivity). RESULTS: The most striking significant difference between the 2 groups was that in conflict situations, patients with NVDs sought a quick solution or expected other people to provide one, which prevented them from understanding the underlying causes of the conflict. CONCLUSIONS: Only if the psychosocial aspects are taken into account can patients with NVD be offered a therapy that treats the causes of the voice disorder. It must be decided individually whether and when a voice training approach or a more psychological-psychotherapeutical approach is preferable.
Resumo:
The maintenance of colour polymorphisms within populations has been a long-standing interest in evolutionary ecology. African cichlid fish contain some of the most striking known cases of this phenomenon. Intrasexual selection can be negative frequency dependent when males bias aggression towards phenotypically similar rivals, stabilizing male colour polymorphisms. We propose that where females are territorial and competitive, aggression biases in females may also promote coexistence of female morphs. We studied a polymorphic population of the cichlid fish Neochromis omnicaeruleus from Lake Victoria, in which three distinct female colour morphs coexist: one plain brown and two blotched morphs. Using simulated intruder choice tests in the laboratory, we show that wild-caught females of each morph bias aggression towards females of their own morph, suggesting that females of all three morphs may have an advantage when their morph is locally the least abundant. This mechanism may contribute to the establishment and stabilization of colour polymorphisms. Next, by crossing the morphs, we generated sisters belonging to different colour morphs. We find no sign of aggression bias in these sisters, making pleiotropy unlikely to explain the association between colour and aggression bias in wild fish, which is maintained in the face of gene flow. We conclude that female-female aggression may be one important force for stabilizing colour polymorphism in cichlid fish.
Resumo:
Adaptation does not necessarily lead to traits which are optimal for the population. This is because selection is often the strongest at the individual or gene level. The evolution of selfishness can lead to a 'tragedy of the commons', where traits such as aggression or social cheating reduce population size and may lead to extinction. This suggests that species-level selection will result whenever species differ in the incentive to be selfish. We explore this idea in a simple model that combines individual-level selection with ecology in two interacting species. Our model is not influenced by kin or trait-group selection. We find that individual selection in combination with competitive exclusion greatly increases the likelihood that selfish species go extinct. A simple example of this would be a vertebrate species that invests heavily into squabbles over breeding sites, which is then excluded by a species that invests more into direct reproduction. A multispecies simulation shows that these extinctions result in communities containing species that are much less selfish. Our results suggest that species-level selection and community dynamics play an important role in regulating the intensity of conflicts in natural populations.
Resumo:
Objective: Suicide attempts are common in patients being treated for alcohol-use disorders (AUDs). However, clinical assessment of suicide risk is difficult. In this Swiss multisite study, we propose a decision tree to facilitate identification of profiles of AUD patients at high risk for suicidal behavior. Method: In this retrospective study, we used a sample of 700 patients (243 female), attending 1 of 12 treatment programs for AUDs in the German-speaking part of Switzerland. Sixty-nine patients who reported a suicide attempt in the 3 months before the index treatment were compared using risk factors with 631 patients without a suicide attempt. Receiver operating characteristic (ROC) analyses were used to identify patients at risk of having had a suicide attempt in the previous 3 months. Results: Consistent with previous empirical findings in AUD patients, a prior history of attempted suicide and severe symptoms of depression and aggression considerably increased the risk of a suicide attempt and, in combination, raised the likelihood of a prior suicide attempt to 52%. In addition, one third of AUD patients who had a history of suicide attempts and previous inpatient psychiatric treatment, or who were male and had previous inpatient psychiatric treatment, also reported a suicide attempt. Conclusions: The empirically supported decision tree helps to identify profiles of suicidal AUD patients in Switzerland and supplements clinicians' judgments in making triage decisions for suicide management.
Resumo:
The origin and maintenance of phenotypic polymorphisms is a classical problem in evolutionary ecology. Aggressive male-male competition can be a source of negative frequency-dependent selection stabilizing phenotypic polymorphisms when aggression is biased toward the own morph. We studied experimental assemblages of red and blue color morphs of the Lake Victoria cichlid fish Pundamilia. Aggression was investigated in mixed-color and single-color assemblages. We found that aggression was indeed biased toward males of the same color, which could in theory reduce aggression levels in mixed-color assemblages and promote coexistence. However, previous studies showed high aggression levels in red and dominance of red over blue males in dyadic interactions, which could hinder coexistence. We found that coexistence in mixed-color assemblages reduced the level of aggression in red males but not in blue males. Red and blue males were equally dominant in mixed-color assemblages, suggesting that predictions derived from dyadic interactions may not be valid for an assemblage situation. The results are consistent with field data: the geographic range of red is nested within that of blue, suggesting that red cannot displace blue. Our study suggests that male-male competition may be a significant force for maintaining phenotypic diversity.