Elevation and reduction of plasma tryptophan and their effects on aggression and perceptual sensitivity in normal males

Data from experimental animals suggest that 5-hydroxytryptamine (5HT) may have an inhibitory effect on aggression, while clinical studies have found a correlation between pathological aggression and low brain 5HT. To investigate this relationship further we used amino acid mixtures designed to raise or lower the levels of the 5HT precursor, tryptophan. Normal male subjects were given tryptophan-depleted, balanced, or tryptophan-supplemented ammo acid mixtures and tested for aggression 5 hours later. The balanced amino acid mixture served as a control for the tryptophan depletion and supplementation. Testing for aggression was done using the Buss paradigm in which subjects deliver electric shocks to a (nonexistent) partner in response to stimulus tones. Duration and intensity of shock delivered were the measures of aggression, while responsivity to the stimulus tones was the measure of perceptual sensitivity. Neither tryptophan supplementation nor tryptophan depletion had any effect on these measures of aggression or perceptual sensitivity. We conclude that raising or lowering the synthesis of brain 5HT through alterations in tryptophan availability does not influence aggression in normal males as measured by the Buss task.     

How impulsiveness, trait anger, and extracurricular activities might affect aggression in school children

Individual differences in personality traits such as impulsivity and trait anger as well as environmental variables have an impact on aggressiveness. We tested a model incorporating the related variables of impulsiveness, trait anger, and aggression and incorporated the possible mediating influences of leisure-time activities. Regression analyses of data from 1129 pre-adolescents and 1093 adolescents (55.4% females) from a study evaluating the Spanish version of the Buss and Perry aggression questionnaire (AQ; Santisteban, Alvarado, & Recio, 2007) showed a relation between impulsiveness (Barratt Impulsiveness Scale) and aggression (AQ). Trait anger (Spielberger’s State-Trait Anger Expression Inventory), the time spent watching TV and playing video games, and the time spent doing homework (all related to impulsiveness) also are related to physical, as well as verbal aggression (with low to moderate coefficients). Multiple mediation analyses confirm that media violence exposure and homework, respectively, can have aggravating and attenuating effects on self-reported aggression. These results provide key variables for longitudinal studies which could reveal the causal nature of the results found with our cross-sectional design.     

Overt and fantasized aggression toward parents by enuretic and nonenuretic children

This study compared the amount and direction of overt and fantasized aggression of enuretic and nonenuretic children. Following the dynamic approach, it was hypothesized that enuretic children would differ from nonenuretics in having more difficulty in expressing overt aggression toward their mothers than toward a neutral figure. In fantasy, enuretic children were expected to express more aggression feelings toward their parents than control subjects. Twenty-eight enuretic subjects and a matched group of control subjects were induced to aggress toward their mothers and toward a neutral figure. The experimental situation was a variation of the Buss (1961) technique for eliciting and measuring aggression. Aggressive fantasies were assessed, using Bene and Anthony's Family Relation Test (1957). A significant interaction was obtained between enuresis/nonenuresis and target figures. Enuretic subjects expressed more aggression toward a neutral figure than toward the mother (p=.05) and differed from the control group in expressing less aggression toward the mother (p=.10). On the fantasy level, a significantly opposite trend to the predicted one emerged: Enuretic subjects showed less aggression toward both parents. The results were discussed with respect to the dynamic and the behavioristic approach to enuresis, and further research directions were suggested.This study is based in part on an M.A. thesis submitted by the second author to the Department of Psychology, Tel-Aviv University,     

Interpolating physical exercise between instigation to aggress and aggression: The role of irritability and emotional susceptibility

Two studies were conducted using the Buss aggression machine paradigm to investigate the mediational role of physical exercise with respect to subsequent aggression in relation to the presence or absence of previous instigation. The irritability level of subjects was taken into account in the first study, and the subject' emotional susceptibility level in the second study. In both studies sex differences were also considered so that each study resulted in a 2 × 2 × 2 × 2 design with ten subjects in each cell. As far as irritability is concerned, experimental subjects (pedaling on a bicycle ergonometer) delivered higher shocks than controls (who just waited out the 10 min the experimental subjects were pedaling), independent of irritability level or of the presence or absence of previous instigation. When emotional susceptibility was taken into consideration, physical exercise associated with high level of emotional susceptibility and previous instigation resulted in increased intensity of the shocks subsequently delivered. These findings are discussed in terms of the importance of stable personality characteristics that may differentially mediate aggression.     

Adult sex role orientation and perceptions of aggressive interactions between girls and boys

We explored how the sex role orientation of adult observers related to their perceptions of boys' and girls' aggression. Sex-typed and androgynous undergraduate subjects viewed videotaped scenes in which one member of a girl-boy pair behaved aggressively toward the other. Unlike androgynous subjects, sex-typed subjects judged boys' aggression to be more intentional than girls' and proposed more severe reprimands for aggressive boys than for aggressive girls. Androgynous subjects recommended more severe reprimands for aggressive girls than sex-typed subjects did. Overall, sex-typed subjects differed from androgynous subjects not in their assessment of the degree of aggressiveness boys and girls expressed, but in their perceptions of the purposefulness of boys' and girls' aggression and how harshly to respond to it. We speculated that sex-typed subjects did not consider girls' aggression to be serious enough to warrant severe reprimands. Thus, during socialization, sex-typed adults perhaps model less aggression in response to girls' aggressive acts than to boys'. In addition, sex-typed adults may convey to girls that their aggression is not an effective means of obtaining adult intervention.     

It's not just what you say,it's how you say it too. Adolescents' hostile attribution of intent and emotional responses to social comments

A highly prevalent and relevant situation in which adolescents have to interpret the intentions of others is when they interact with peers. We therefore successfully introduced a new paradigm to measure hostile attribution bias (HAB) and emotional responses to such social interactions and examined how it related to youth's aggressiveness. We presented 881 adolescents (M_age = 14.35 years; SD = 1.23; 48.1% male) with audio fragments of age-mates expressing social comments that varied in content (e.g., what the person says) and tone of voice (e.g., how the person says it). Participants' peers also reported on their aggressiveness. In general, added negativity of content and tone was driving the youth's intent attribution and emotional responses to the comments. In line with the Social Information Processing model, we found more hostile attribution of intent and more negative emotional responses of aggressive youth to ambiguous stimuli. Aggression was also related to more hostile intent attributions when both content and tone were negative. Unlike most studies on HAB, the aggression effects in the current study emerged for girls, but not boys. Implications of these results and future use of the experimental paradigm are discussed.     

A direct assessment of the role of state and trait negative emotion in aggressive behavior

Affective priming of aggression was examined in groups low and high in trait negative emotionality (NEM) using a Buss aggression paradigm. Negative affect was induced by exposure to aversive air blasts during some intervals (threat) and not others (safe). Phasic negative affect was assessed using startle reflex potentiation, and tonic distress was indexed by startle sensitization. Participants delivered shocks faster during threat versus safe intervals, indicating that phasic distress primed aggression. Following initial exposure to air blasts, high NEM participants showed enhanced tonic distress and delivered persistently more intense shocks than low NEM participants. These findings indicate that sustained negative affect biases high stress-reactive individuals toward more intense acts of aggression, with phasic distress affecting the rapidity of aggressive response.     

Repeated exposure to violent and nonviolent pornography: Likelihood of raping ratings and laboratory aggression against women

This study examined the relatively long-term effects of repeated exposure to violent and nonviolent pornography on male' laboratory aggression against women. Self-reported likelihood of raping was also assessed as an individual differences variable that might mediate susceptibility to the effects of pornography and to ascertain whether it predicted actual aggressive behavior. Subjects were randomly assigned to the sexually violent, sexually nonviolent, or control exposure conditions. Those assigned to the sexually violent or sexually nonviolent conditions were exposed over a four-week period to ten stimuli including feature-length films and written and pictorial depictions, whereas control subjects were not exposed to any stimuli. About a week following the end of the exposure phase, subjects participated in what they believed to be a totally unrelated experiment in which aggression was assessed within a Buss paradigm. Exposure to the violent or nonviolent pornographic stimuli was not found to affect laboratory aggression. These data are discussed in terms of a recent analysis of media effects emphasizing the temporary activation of ideas in audience' minds. Likelihood of raping ratings was found to predict laboratory aggression.     

Creating your own hostile environment: a laboratory examination of trait aggressiveness and the violence escalation cycle

A dyadic interactive aggression paradigm tested hypotheses from the General Aggression Model about how trait aggressiveness can create behaviorally hostile social environments. Pairs of college student participants competed in a modified reaction time task in which they repeatedly delivered and received each other's punishments. The trait aggressiveness of both participants influenced the punishment intensities (aggression level) set by each member of the dyad on later trials. Furthermore, there was a pattern of escalation from early to later trials. These trait aggressiveness effects (both self and partner) on later aggressive behavior were largely mediated by partner aggression levels during early trials. Results also suggested two aggressive motives--hostile and instrumental--resulted from high partner aggression during early trials and these motives partially mediated the effects of trait aggressiveness and of early trial aggression on later aggressive behavior.     

P300 to emotionally relevant stimuli as an indicator of aggression levels

Severe acts of aggression have been associated with prefrontal dysfunction. Less severe aggression may be associated with more subtle abnormalities. P300 event‐related potentials were recorded from 32 healthy volunteers during a novel modified oddball task. The task required participants to respond only to rare, food words (targets), which occurred randomly among neutral words. Aggressive words appeared randomly with the same frequency as the target words. A median split divided subjects into high‐ and low‐aggression groups based on their scores on the Buss–Durkee Hostility Inventory. The groups did not differ in their responses to the target words. Participants with higher aggression scores had lowered responses to the aggressive words at the frontal relative to the other electrode sites. Cognitive processing of aggressive stimuli was less efficient at frontal sites in individuals who reported higher levels of aggression. This result extends work showing frontal P300 decrements in more severe aggressive groups, using simple oddball tasks. Aggr. Behav. 32:1–8, 2006. © 2006 Wiley‐Liss, Inc.     

Test-dependent expression of behavioral syndromes: A study of aggressiveness,activity, and stress of chub

Aggressiveness has been one of the behavioral traits most examined with various standard testing methods. We used two distinct methods (the mirror and the real opponent tests) to evaluate individual aggression and relate it to the activity and individual stress of chub (Squalius cephalus L.). Three hypotheses were formulated and tested: (a) there is a significant positive relationship between the aggressiveness of individuals measured with the mirror and the real opponent tests, indicating their convergent validity; (b) the irregularities in response to the aggressiveness and activity tests lead to the context-specific expression of the behavioral syndromes; and (c) there is a significant positive relationship between the stress induced in individuals by both tests of aggressiveness, demonstrating individually consistent stress-coping strategies. The first and the second hypothesis were confirmed, while the third hypothesis was rejected. Our results suggest that particular tests of aggressiveness could act as a situation with high strength, leaving little variation between individual responses. Thus, we propose that for the proper interpretation of various studies using different tests to study identical behavioral traits, it is important to consider the convergent validity of not only the tested behavioral traits but also the individual stress responses. The chub also showed stress relieve through aggressiveness, suggesting the species as a prospective animal model to the study interaction between the stress and the aggressiveness. A detailed aggression ethogram of chub was provided to facilitate the use of this specie in future studies.     

Dynamics of hostile aggression: Influence of anger,hurt instructions,and victim pain feedback

The research basically examined some of the dynamics of hostile aggression by looking at the effects of different Buss procedure instructions and levels of victim pain feedback on the aggressive behavior of angered and nonangered men. In a 2 × 2 × 2 completely crossed factorial experiment, male undergraduates were initially either angered or not by an experimental accomplice. When later given the ostensible opportunity to administer shocks to the same accomplice in a typical Buss procedure, the subjects were either told that longer and more intense shocks would probably interfere with the person's learning as well as causing him more pain (hurt instructions) or given no information about the effects of shocks on learning (standard instructions). Finally, after each shock they administered, the subjects were provided with either high or low victim pain feedback. The angered men were significantly more aggressive than their nonangered counterparts, and a significant interaction between anger and instructions indicated this was especially true for the men given hurt instructions. Significant interactions between the other independent variables and trial blocks revealed that the angered men, particularly those receiving hurt instructions and high victim pain feedback, displayed the greates increases in aggression. The results provide qualified support for the derived proposition about hostile aggression that signs and/or knowledge of victim injury and pain can stimulate more intense aggression from angry individuals.     

Concurrent and predictive validity of self-reported aggressiveness

The subjects (60 boys) were drawn from the sample of a longitudinal study of social development and represented extremely aggressive, anxious, constructive, and submissive behaviour at the age of 8. They were presented with three question series concerning (1) their responses to aggressive attacks; (2) reactions in frustration situations presented in short stories; and (3) their aggressive initiatives. In each series the type of aggressive behaviour, attacker, victim, and other situational factors were systematically varied. In series 2 the type of response, open-ended or forced-choice, was also varied. The results showed that the most valid way of studying boys' self-observations on their aggressive behaviour was to ask if they attack somebody without a specific reason (series 3). This correlated with contemporaneous overt aggression at the age of 8 and predicted aggressiveness and various characteristics of antisocial aggressive development at the ages of 14 and 19. Self-observations on one's physical aggression were more valid for ratings of overt aggressiveness than on verbal aggression. The open-ended or forced-choice type of response did not affect the validity of aggressive responses. Of the categories of nonaggression, ‘conciliatory responses’ had the highest concurrent and predictive validity for constructiveness and other indicators of strong self-control.     

Evaluation of a Spanish version of the Buss and Perry aggression questionnaire: Some personal and situational factors related to the aggression scores of young subjects

The psychometric properties of a Spanish translation of the Buss and Perry aggression questionnaire adapted for pre-adolescents and adolescents have been studied. A maximum-likelihood confirmatory factor analysis corroborates Buss and Perry’s four-factor structure. The internal consistency of each factor and of the total score has proved to be satisfactory. The four factors are more closely interrelated in pre-adolescents than in adolescents.A second aim of this work has been to further our understanding of the possible relationship between aggression scores and certain outside-school activities of the subjects studied. Two thousand two hundred and eight students filled in the questionnaire together with a self-report concerning their habits. The results show that the aggression scores rise concomitantly with time spent watching television and playing video games and decrease the greater the time devoted to extra-curricular reading or moderate amounts of homework. Statistically significant differences relating to age and gender were also found.     

Digit Ratio 2D:4D,facial masculinization and aggressiveness in Spanish adolescents / Índice 2D:4D,masculinización facial y agresividad en adolescentes españoles

Abstract

This study aims to test whether two morphometric characteristics, the second to fourth finger length ratio (2D:4D index) and the facial width-to-height ratio (FWH index), which reflects the degree of facial masculinization, are related to aggression in adolescents of both sexes. Previous studies have proposed that the 2D:4D index (a trait related to prenatal testosterone) and the FWH (related to testosterone during puberty) are related to aggressiveness in adult males (although there is evidence to the contrary). In the present study we investigate the relationship of both traits with different measures of aggression in a mixed population of 296 adolescents (14–19 years old). We did not find relationships between 2D:4D and FWH with aggressiveness. Furthermore, our results suggest that the FWH index must be used only after controlling for body mass index.     

The effects of a model's success or failure on subsequent aggressive behavior

It was of interest in the present study to examine the influence of both aggressive and nonaggressive models who are successful or nonsuccessful in reducing aggression from an aggressive opponent. Male and female subjects viewed a same-sexed model interact with an aggressive opponent in a reaction time task. Half the subjects observed an aggressive model while the remaining subjects observed a nonaggressive model. For half the subjects the model was successful in reducing the aggressiveness of the opponent. Results indicated that both the model's behavior and the consequences to the model (success/nonsuccess) were important determinants of subsequent aggression by the subject. Results are discussed in terms of current research and theory in aggression control.     

Who is this Donald? How social categorization affects aggression‐priming effects

When investigating the effects of aggression on person perception, many studies have relied on the famous ‘Donald’ paradigm (e.g., Srull & Wyer, 1979 ). Little attention has been paid, however, to the role that is played by the social identity of Donald (the target of perception) in such effects. Three studies with Dutch participants, consistently reveal that judgments of an ingroup (Dutch) target are less prone to be affected by aggression priming than judgments of an outgroup (Moroccan, Surinamese, German) target, and that this effect is moderated by the extent to which the target's group is associated with aggressiveness. Importantly, the studies show that such association can be created not only via well‐established stereotypes (e.g., ‘Moroccans are aggressive’), but also via subtle contextual priming. When priming activates an association between ingroup and aggressiveness (‘The Dutch are aggressive’), the subsequent evaluation of the ingroup targets can also be influenced negatively. The present research thus demonstrates that social categorizations and the contextual associations attached to them delineate an important boundary condition for aggression priming effects. Copyright © 2006 John Wiley & Sons, Ltd.     

不同类型社会排斥中归因诱导对攻击性的影响

为探讨归因诱导能否缓解不同类型社会排斥引发的攻击性,研究分别采用网络任务范式和网络投球范式启动拒绝和放逐,进行不同的归因诱导后用科研助理评分范式测量攻击性。结果发现,放逐引发的攻击性比拒绝高;归因诱导对拒绝引发的攻击性有显著影响,对被拒绝者进行内部归因诱导后其攻击性显著低于外部归因诱导组和无归因诱导组;归因诱导对放逐引发的攻击性无显著影响。研究表明归因诱导对拒绝型直接排斥引发的攻击性有缓解作用。