Higher Aggression Scores Research Articles

Depression and aggression in never-married men in China: a growing problem

China has the highest excess of male births in the world at 118 to every 100 female, with a current excess of 20 million men of reproductive age. The impact on the psychological well-being of the large numbers of men who will never marry is unclear. This study was carried out to test the hypothesis that older never-married men are more predisposed to depression, low self-esteem and aggression. The study was a cross-sectional survey using a self-completion questionnaire conducted in high sex ratio rural areas of Yunnan and Guizhou provinces. The tools used were the Beck Depression Inventory, Rosenberg's Self-Esteem Scale and the Bryant-Smith Aggression questionnaire. A total of 1,059 never-married men and 1,066 married men aged 30-40 completed questionnaires. Never-married men were financially poorer and had lower education levels than married ones. After adjusting for age, education and income, never-married men were significantly more likely to have lower self-esteem scores (P<0.001), higher depression scores (P<0.001), higher aggression scores (P<0.001) and were more likely to have suicidal thoughts or wishes (P<0.001) than married men. The high prevalence of severe depression and suicide ideation in these men is of particular concern. In rural China mental health services are currently very sparse, but rural doctors could be trained to use a check score to identify severe depression, and refer as appropriate to specialist services.

Borderline personality disorder in suicidal adolescents

The diagnosis of borderline personality disorder (BPD) in adolescents has been controversial. Thus, few studies have examined BPD in suicidal adolescents, even though it is strongly associated with suicidal behaviours in adults. This study examines differences between suicidal adolescents with (n = 47) and without (n = 72) BPD on history and characteristics of suicidal behaviour, Axis I co-morbidity, affect regulation and aggression. Assessments were completed with both adolescents and parents, and consensus ratings based on best available data were analysed. BPD participants were more likely to have a history of suicide attempts and to have been admitted because of a suicide attempt (vs. suicidal ideation). There were no significant differences in self-injurious behaviours or degree of suicidal ideation. BPD participants also had more psychiatric co-morbidity and higher aggression scores but no significant differences in affective dysregulation compared with suicidal adolescents without BPD. Diagnostic stability over 6 months was modest. Our results demonstrate that, compared with other acutely suicidal adolescents, the clinical profile of BPD participants is unique and suggests an increased risk for suicidal behaviours. This extends upon other studies that support the construct validity of BPD during adolescence and suggests that BPD should be considered in suicide risk assessment for adolescents.

Prospective predictors of adolescent suicidality: 6-month post-hospitalization follow-up

The aim of this study was to examine prospective predictors of suicide events, defined as suicide attempts or emergency interventions to reduce suicide risk, in 119 adolescents admitted to an in-patient psychiatric unit for suicidal behaviors and followed naturalistically for 6 months. Method Structured diagnostic interviews and self-report instruments were administered to adolescent participants and their parent(s) to assess demographic variables, history of suicidal behavior, psychiatric disorders, family environment and personality/temperament. Baseline variables that significantly predicted time to a suicide event during follow-up were Black race, high suicidal ideation in the past month, post-traumatic stress disorder (PTSD), childhood sexual abuse (CSA), borderline personality disorder (BPD), low scores on positive affectivity, and high scores on aggression. In a multivariate Cox regression analysis, only Black race, CSA, positive affect intensity and high aggression scores remained significant. Our findings suggest the following for adolescent populations: (1) in a very high-risk population, risk factors for future attempts may be more difficult to ascertain and some established risk factors (e.g. past suicide attempt) may not distinguish as well; and (2) cross-cutting constructs (e.g. affective and behavioral dysregulation) that underlie multiple psychiatric disorders may be stronger predictors of recurrent suicide events than psychiatric diagnoses. Our finding with respect to positive affect intensity is novel and may have practical implications for the assessment and treatment of adolescent suicide attempters.

Fine- and Broad-Scale Approaches to Understanding the Evolution of Aggression in Crickets

Male field crickets frequently engage in agonistic contests to establish dominance in social interactions and gain access to mate attraction territories. Crickets (Orthoptera: Gryllidae) are often used as a model taxon to study aggression, but limited documentation of aggression in some cricket species hinders our understanding of its evolutionary costs and benefits. Our study investigated cricket aggression at two scales: the within-species scale for two cricket species, Gryllus assimilis and G. veletis, whose aggression had not been adequately documented and the among-species scale to detect evolutionary patterns in species’ levels of aggression. In both G. veletis and G. assimilis, winners spent more time being aggressive than losers, but they were not larger or heavier. Collectively, our results reveal that G. veletis males are more aggressive than G. assimilis. Male G. veletis had higher aggression scores that male G. assimilis. The majority of G. veletis contests escalated to grappling (a highly aggressive behavior), while less than one quarter of G. assimilis contests escalated to grappling. Further, G. veletis males transitioned between two of the most aggressive behaviors most often while G. assimilis transitioned between two of the least aggressive behaviors most often. We integrate this new information on aggression for G. assimilis and G. veletis with previously documented aggression data for many cricket species to investigate aggression in a broader evolutionary context than previously possible. Within a phylogenetic context, we test the hypothesis that species whose males use burrows from which to call and attract females are more aggressive than species with non-burrowing males. We found evidence consistent with this hypothesis; species with burrowing males tended to be more aggressive than species with non-burrowing males. Together, our study provides fine-scale understanding of aggression in two cricket species and broad-scale evolutionary context for aggression across cricket species.

The winner and loser effect, serotonin transporter genotype, and the display of offensive aggression

Aggressive behaviour results from a complex interplay between genetic and environmental factors. Key modulators of aggression include the serotonergic system on the molecular level and experience in prior aggressive contests as an environmental factor. The aim of this study was to elucidate the effects of fighting experience on the display of offensive aggressive behaviour in adult male mice varying in serotonin transporter (5-HTT) genotype. 5-HTT +/+, 5-HTT +/− and 5-HTT −/− mice were given either a winning or a losing experience on each of three consecutive days and were subsequently observed for their offensive aggressive behaviour as residents against a docile intruder from the C3H strain in a resident–intruder paradigm. The main findings were: There was no significant difference between the amount of offensive aggressive behaviour displayed by the genotypes. Winners showed more engagement with the intruder, attacked him faster and exhibited overall higher aggression scores than losers. There was no significant genotype × social experience interaction: winning and losing had a similar effect on offensive aggressive behaviour in all three 5-HTT genotypes.We conclude that social experience in terms of having been a winner or having been a loser rather than the 5-HTT genotype determines the behaviour towards a docile intruder.

P03-130 - Effects of a diminished serotonin synthesis on memory and impulsive aggression in adult ADHD

IntroductionNumerous results from investigations including children with ADHD show associations between a diminished serotonin synthesis and memory impairments as well as higher aggression scores. The aim of the present study was the investigation of the association between a diminished serotonin synthesis, logical memory and impulsive aggression in male adult patients with ADHD.MethodTwenty male adult patients with ADHD and twenty healthy controls were recruited for this double-blind within subjects crossover study. Subjects completed the Rapid Tryptophan Depletion (RTD) Test or a placebo condition (balanced amino acid load) on either one of two examination days. Clinical variables and general intellectual functioning were assessed. The neuropsychological test battery included the subtest logical memory from the Wechsler Memory Scale (WMS-R), self-assessment of aggression as well as the Point Subtraction Aggression Game (PSAG).ResultsStatistical analysis revealed significant memory impairments of ADHD patients, which were associated with severity of symptoms in early childhood as well as subjective aggression scores. Effects of the tryptophan depletion were not found, neither for the logical memory subtest nor performance in the PSAG.ConclusionsIn contrast to previous studies, these findings suggest that the serotonergic system as reflected by the RTD Test has no effect on memory performance or impulsive aggression. However, these results may be due to possible interactions of other catecholamine systems with the serotonergic system that were not controlled in this study. Therefore an additional study is needed to further explore the catecholamine systems and their effects on memory and impulsive aggression.

Moral or Religious Objections to Suicide May Protect Against Suicidal Behavior in Bipolar Disorder

Patients with bipolar disorder are prone to suicidal behavior, yet possible protective mechanisms are rarely studied. We investigated a possible protective role for moral or religious objections to suicide against suicidal ideation and attempts in depressed bipolar patients. A retrospective case control study of 149 depressed bipolar patients (DSM-III-R criteria) in a tertiary care university research clinic was conducted. Patients who reported religious affiliation were compared with 51 patients without religious affiliation in terms of sociodemographic and clinical characteristics and history of suicidal behavior. The primary outcome measure was the moral or religious objections to suicide subscale of the Reasons for Living Inventory (RFLI). Religiously affiliated patients had more children and more family-oriented social networks than nonaffiliated patients. As for clinical variables, religiously affiliated patients had fewer past suicide attempts, had fewer suicides in first-degree relatives, and were older at the time of first suicide attempt than unaffiliated patients. Furthermore, patients with religious affiliation had comparatively higher scores on the moral or religious objections to suicide subscale of the RFLI, lower lifetime aggression, and less comorbid alcohol and substance abuse and childhood abuse experience. After controlling for confounders, higher aggression scores (P = .001) and lower score on the moral or religious objections to suicide subscale of the RFLI (P < .001) were significantly associated with suicidal behavior in depressed bipolar patients. Moral or religious objections to suicide mediated the effects of religious affiliation on suicidal behavior in this sample. Higher score on the moral or religious objections to suicide subscale of the RFLI is associated with fewer suicidal acts in depressed bipolar patients. The strength of this association was comparable to that of aggression scores and suicidal behavior, and had an independent effect. A possible protective role of moral or religious objections to suicide deserves consideration in the assessment and treatment of suicidality in bipolar disorder.

The effects of video game realism on attention, retention and aggressive outcomes

This study used a between subjects, post-test only design to test the effects of video game realism (Doom 1 vs. Doom 3) and a control condition on attention, retention and aggressive outcomes. Overall, those who played Doom 3 perceived it as significantly more realistic than those who played Doom 1, thus providing validity for the manipulation. Next, those who played Doom 3 were significantly more attentive and experienced more presence than those who played Doom 1. Furthermore, playing either Doom game resulted in more aggression than playing no game and physically aggressive intentions were higher among those who played Doom 3 as compared to those who played Doom 1. Lastly, we tested for any possible interaction between realism and the attention and retention subfunctions on production and we found that, compared to the other players, those who experienced greater identification among those playing Doom 3 had higher verbal aggression. For physical aggression, those who played Doom 3 and experienced more attention and greater identification had higher aggression scores than those in the other conditions.

Personality and attempted suicide. Analysis of anger, aggression and impulsivity

Suicide is one of the leading causes of death worldwide, mortality from suicide being approximately 2%. Attempted suicide appears to be a major risk factor for suicide completion. Anger, aggression and impulsivity are personality traits associated with suicide attempt. In this study we analysed a part of a previously reported sample in order to test anger, impulsivity and temperament/character scales as predictors of aggression and self-aggression in suicide attempters and to compare anger- and aggression-related traits between impulsive and premeditated suicide attempts as well as between violent and non-violent suicide methods.One-hundred-eleven consecutively admitted inpatients with a lifetime history of attempted suicide were assessed for anger (State-Trait Anger Expression Inventory, STAXI), aggression (Questionnaire for Measuring Factors of Aggression, FAF) and temperament/character (Temperament and Character Inventory, TCI).Higher aggression scores, as measured by FAF, were predicted by being male, meeting criteria for borderline personality disorder and having higher angry temperament scores as assessed by STAXI; low cooperativeness was also associated with aggression but not after controlling for STAXI scales. TCI dimensions associated with self-aggression were high harm avoidance, high impulsivity and low self-directedness; state anger, inwardly directed anger and inhibition of aggression were also predictors of self-aggression.In conclusion, impulsivity and harm avoidance have emerged as temperament dimensions independently associated with self-aggressive tendencies in personality. Such interactions could explain the correlation between temperament and suicidality but further research is needed. Anger and self-directedness appear to have some effects on suicide attempt.

Family History of Suicide and Personality

The objective of this study was to analyze the impact of family history of suicidal behaviour on psychopathlogical features of inmates. A sample of 1,179 prisoners had a psychiatric interview including the Brown-Goodwin Assessment for Lifetime History of Aggression (BGLHA). Prisoners completed the Barratt Impulsivity Scale (BIS), Buss-Durkee Hostility Inventory (BDHI), and Eysenck Personality Questionnaire (EPQ). Prisoners with a family history of suicide were compared with prisoners without a family history of suicide on clinical and personality variables. Seventy of the 1,179 prisoners (5.9%) had a family history of suicide. Significantly more FHS positive prisoners had attempted suicide compared with FHS negative prisoners (36% vs. 12%, P < 0.0001). Significantly more FHS positive prisoners had a previous history of convictions, a history of juvenile convictions, and had exhibited aggressive behavior in jail. FHS positive prisoners had significantly higher aggression scores on the BGLHA, higher hostility scores on the BDHI, higher impulsivity scores on the BIS, and higher neuroticism scores on the EPQ. A family history of suicide may be a useful clinical indicator that a prisoner is at increased risk for suicidal behaviour and may have problems with impulsive-aggression.

Effect of tactile stimulation in common human–dog interactions on the behavior and physiology of dogs

in any element of Group D were significantly associated with a history of biting dogs (P 5 0.001), producing 54.9% correct positives. Other factors influencing aggression scores and biting history included sex, breed, and obedience. Intact males bit other dogs with high probability (c 5 16.4, df 5 3, P 5 0.001). There also was a breed difference for high aggression scores in Group D (c 5 36.7, df 5 14, P 5 0.001) and for a history of biting dogs (c 5 33.1, df 5 14, P 5 0.003). A biting history with dogs was not significantly correlated to any particular form of training, but a poor obedience score was correlated with high aggression scores in Group D (K-W c 5 19.2, df 5 3, p , 0.001), and there was also a breed difference for obedience (K-W c 5 37.0, df 5 3, P , 0.001). Owners using physical punishment had dogs with low obedience levels (K-W c 5 30.9, df 5 3, P , 0.001). The opposite applied for using verbal reinforcement (K-W c 5 24.2, df 5 3, P , 0.001). These preliminary results show that such formal tests, done by experts in a standardized way, appear to be useful retrospective tools for identifying danger originating from dogs. Whether such dog–dog tests are of any prospective use needs to be investigated further. Many factors influence dog behavior in individual situations. All factors have to be thoroughly evaluated, especially as they interact with and influence each other. Further research will need to emphasize the owner’s influence, beginning with the initial decision to purchase a particular breed.

‘It's your round!’ – female aggression in licensed premises

Aggression involving young females in licensed premises was examined. Phase 1 investigated whether it was possible to distinguish between females who had been involved in an aggressive incident in a licensed premises from those who had not by looking at ‘ladette’ characteristics (i.e. heavy alcohol consumption, consumption of male-orientated drinks and higher aggression). Fifty-seven female participants completed both a drinking habits questionnaire and an aggression questionnaire. The results supported the hypothesis that females who had been involved in licensed premise aggression were heavier drinkers, were more likely to consume male-orientated drinks, and had higher aggression scores than those who reported never having been involved in such aggression. A logistic regression, however, showed only total alcohol consumption and self-reported physical aggression made unique independent predictions of fighting behaviour. Phase 2 investigated whether four motivations identified in previous research examining licensed premises aggression in males were relevant to such aggression involving females. Twelve participants from phase 1 were interviewed using a semi-structured format. The results indicated that although females reported similar motivations as males for their involvement in licensed premise aggression, they also appeared to be motivated by gender-specific concerns such as taking offence to another female's ‘flirtatious’ behaviour.

MAOA Genotype, Maltreatment, and Aggressive Behavior: The Changing Impact of Genotype at Varying Levels of Trauma

Childhood adversity has been shown to interact with monoamine oxidase-A (MAOA) genotype to confer risk for antisocial behavior. Studies examining this gene-by-environment (G x E) association, however, have produced mixed results. Relevant research is reviewed, and results of a study with 114 children (73 maltreated and 41 control subjects) are presented. The maltreated children represent the extreme on a continuum of adversity and were assessed at a time of extreme stress-shortly after removal from their parents' care due to abuse. Measures of aggressive behavior were obtained using standard research instruments, and monoamine oxidase-A MAOA genotypes were obtained from saliva-derived DNA specimens. Population structure was controlled for using ancestral proportion scores computed on the basis of genotypes of ancestry informative markers. Many prior investigations appear to have had reduced power to detect the predicted G x E interaction because of low base rates of maltreatment and antisocial behavior in their samples and failure to use optimal procedures to control for population structure in ethnically diverse cohorts. In this investigation, a significant interaction was detected between exposure to moderate trauma and the "low-activity" MAOA genotype in conferring risk for aggression. Children with exposure to extreme levels of trauma, however, had high aggression scores regardless of genotype. Our study suggests that problems in aggressive behavior in maltreated children are moderated by MAOA genotype, but only up to moderate levels of trauma exposure. Extreme levels of trauma appear to overshadow the effect of MAOA genotype, especially in children assessed at time of acute crisis.

Faustlos - Gewaltprävention in der Grundschule

Faustlos is a violence prevention program for primary school and preschool children for the promotion of social and emotional competences. The curriculum focuses on the promotion of empathy, impulse control and anger management. The program was evaluated over a period of three years in 13 first and second grade classes. Positive effects of the curriculum were shown especially on aggressive behaviour for boys and children with high aggression scores and on the promotion of empathy.

Substance use disorders and suicide attempts in bipolar subtypes

Bipolar disorder (BD) is associated with high rates of suicide attempt and completion. Substance use disorders (SUD) have been identified as potent risk factors for suicidal behavior in BD. However, little is known concerning differences between BD subtypes with regard to SUD as a risk factor for suicidal behavior. We studied previous suicidal behavior in adults with a major depressive episode in context of BD type I (BD-I; N = 96) or BD type II (BD-II; N = 42), with and without history of SUD. Logistic regressions assessed the association between SUD and suicide attempt history by BD type, and exploratory analyses examined the effects of other clinical characteristics on these relationships. SUD were associated with suicide attempt in BD-I but not BD-II, an effect not attributable to sample size differences. The higher suicide attempt rate associated with alcoholism in BD-I was mostly explained by higher aggression scores, and earlier age of BD onset increased the likelihood that alcohol use disorder would be associated with suicide attempt(s). The higher suicide attempt rate associated with other drug use disorders in BD-I was collectively explained by higher impulsivity, hostility, and aggression scores. The presence of both alcohol and drug use disorders increased odds of a history of suicide attempt in a multiplicative fashion: 97% of BD-I who had both co-morbid drug and alcohol use disorders had made a suicide attempt. A critical next question is how to target SUD and aggressive traits for prevention of suicidal behavior in BD-I.

Sex differences in the familial transmission of mood disorders

Background Mood disorders exhibit familial transmission due to both environmental and genetic risk factors. Mood disorders are more common in women, yet the role of gender in the familial transmission of mood disorders is unclear. This study examines rates of mood disorder transmission to offspring based on the sex of affected parent, sex of offspring and role of clinical factors, such as childhood abuse history, comorbid psychiatric disorders, and traits of aggression and impulsivity. Methods Risk of transmission of mood disorder to offspring from females and males was compared in a sample of 272 probands with a major mood disorder using generalized estimating equations (GEE). Demographic and clinical characteristics of all male and female probands were compared. Characteristics that differed in probands were entered into the model to obtain an unbiased test of gender differences in transmission rate. Multivariate GEE models, one for male probands and one for female probands, were used to test for risk factors in transmission of mood disorder. Results Familial transmission rate of mood disorders from female probands was almost double that of males. There was no difference in transmission to male or female offspring. For male probands, offspring mood disorder was independently associated with earlier age of proband mood disorder onset, greater number of proband years ill, and proband history of childhood abuse. For female probands, offspring mood disorder was associated with higher aggression scores in probands. Limitations We did not directly interview offspring and also had limited data on psychopathology in co-parents. This is a cross-sectional study and cannot account for emergence of illness in offspring in the future. Conclusions The two-fold higher rate of maternal transmission of mood disorder may reflect differences in regulation of maternal and paternal transmission of mood disorder. Future studies need to determine the relative contribution of genetic and non-genetic factors and identify the factors responsible for higher rates of transmission of mood disorders by females with a mood disorder.

A Pilot Study on Differences in Aggression in New York City and Madrid, Spain, and Their Possible Impact on Suicidal Behavior

Published results from a U.S. study of depressed suicide attempters and a Madrid, Spain, study including all consecutively admitted suicide attempters suggested that aggression scores were higher in U.S. attempters. This observation led us to compare depressed attempters and controls from both suicide research centers and explore whether New York City (NYC) patients carry out suicidal acts of greater lethality than patients in Madrid. The study goals were (1) to compare aggression scores in attempters and healthy volunteers between the 2 cities and (2) to determine whether higher aggression scores are associated with greater medical lethality of suicide attempts. The respective samples from NYC and Madrid included attempters with a DSM-IV diagnosis of major depressive disorder (N = 117 and N = 133) and healthy controls (N = 90 and N = 317). Aggression scores, measured by the Brown-Goodwin Scale, in attempters and healthy volunteers from both sites were compared using an analysis of variance model. The relationship between lethality of suicidal acts and aggression scores in attempters was assessed using logistic regression analyses. NYC subjects were recruited from 1998 to 2001, and Madrid subjects were selected from consecutive admissions in 1999. Depressed suicide attempters from NYC made attempts of greater lethality and reported more lifetime aggressive behavior than depressed attempters in Madrid. NYC healthy volunteers also reported more aggression than their Madrid counterparts. This pilot study suggests that the greater lethality of suicidal behavior in NYC compared to Madrid is related to higher aggression levels, although the data have limitations. Cross-cultural studies are needed to verify whether aggression and higher lethality suicide attempts share a common diathesis explaining the higher suicide rates in NYC.

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.

Digit length ratios predict reactive aggression in women, but not in men

Considerable evidence suggests that digit length and dermatoglyphic asymmetry patterns in the hand are affected by early exposure to androgens. Because androgens play an important role in sexual differentiation of morphological and behavioral traits, digit length patterns often display sex differences. When present, sex differences in digit lengths are more pronounced on the right side as compared to the left side. Moreover, the ratio of the second to fourth digit length (2D:4D) in the right hand is inversely correlated with testosterone (T) in men. Because T is implicated in agonistic behavior, 2D:4D may be used as a marker of androgen exposure and subsequent behavioral variation in adulthood. Consequently, we investigated the relationships among 2D:4D, directional asymmetry of 2D:4D (left hand 2D:4D minus right hand 2D:4D) as a variant of T, and human reactive aggression. One hundred young men ( n = 51) and women ( n = 49) participated in our experiments (mean age = 20.1 years). Participants called two noncompliant confederates to solicit donations for a fictitious charity organization and selected follow-up letters after the calls. The force exerted when hanging up the phone and the “tone” of the follow-up letters were used to assess reactive aggression. High aggression scores were associated with high directional asymmetry of 2D:4D and masculinized (low) right hand 2D:4D, only in females and under high provocation. Directional asymmetry of 2D:4D was positively correlated with T in males (pooled data, n = 97). Taken together, these data confirm the predominantly right-sided influence of androgens on digit length and suggest that digit length ratios may be associated with female reactive aggression when sufficient provocation is present.

La relación entre los juegos de viodeo violentos, la aculturación y la agresión entre adolescentes latinos

Multiple factors are involved in the occurrence of aggressive behavior. The purpose of this study was to evaluate the hypotheses that Latino middle school children exposed to higher levels of video game playing will exhibit a higher level of aggression and fighting compared to children exposed to lower levels and that the more acculturated middle school Latino children will play more video games and will prefer more violent video games compared to less acculturated middle school Latino children. This study involved 5,831 students attending eight public schools in Texas. A linear relationship was observed between the time spent playing video games and aggression scores. Higher aggression scores were significantly associated with heavier video playing for boys and girls (p < 0.0001). The more students played video games, the more they fought at school (p < 0.0001). As Latino middle school students were more acculturated, their preference for violent video game playing increased, as well as the amount of time they played video games. Students who reported speaking more Spanish at home and with their friends were less likely to spend large amounts of time playing video games and less likely to prefer violent video games (p < 0.05).