Motivation and emotion/Book/2013/Aggression

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Aggression: What is the role of aggression and how can aggression be managed?


Have you ever experienced road rage? Pushed one of your mates because they betrayed you? Have you ever been the target of someone elses aggression and not known what to do about it? Could you have problematic anger? This chapter will inform you of the types of aggression, risk factors for increased aggression, the theories behind your emotions and the behavioural response elicited and how to manage aggression in yourself and in others through different therapies and techniques.

Overview[edit]

Aggression is a verbal or physical behaviour that involves delivery of a harmful stimulus with the intent to harm. Aggression is not assertiveness and is not accidental. There are five main types of aggression: Impulsive, Retaliatory, Instrumental, Angry, Relational Aggression. Research on aggressive behaviour and the explanations that accompany it have varied and changed over time.

In modern day several theories that although differ, can also be arguably linked[grammar?]. These include Psychoanalytic Theory, Social Learning Theory, Social Cognitive Theory, General Aggression Model, frustration-aggression hypothesis, cognitive neo-associationist model and evolutionary/biological theories.

There are many causes of aggression these include Situation- centred Factors such as a verbal or physical attack, frustration from feeling blocked or hindered in achieving goals, Physical discomfort or pain and exposure to violent media. Other causes are referred to as Person-centred Factors and include: gender, the presence of an extra Y chromosome, a decrease in oestrogen and progesterone and the consumption of alcohol. Personality disorders such as Borderline, Antisocial and narcissistic also increase the risks of acquiring aggressive tendencies.

Aggression can be used in beneficial ways. These include co-opting resources from others, as a defence mechanism, inflicting costs on intrasexual rivals, attain power or status, restore damaged self-image and enhance problem solving and communication.However the negatives of problematic anger include; health issues, the destruction of relationships and property, the loss of employment, criminal activity, physical/emotional harm to the self and others, poor communication skills, diminished respect etc.

Anger can be managed in the workplace, with children, using Cognitive behavioural therapies, through the use of drugs and anger management programs, with focus on mindfulness. Finally anger can be managed by the individual through relaxation or through a professional if the individual chooses to seek the help.

Aggression[edit]

Aggression is a verbal or physical behaviour that involves delivery of a harmful stimulus such as an insult or a physical blow such as a punch or kick to another person with the intent to harm that person. Aggression is not assertiveness Assertiveness and is not accidental. There are five main types of aggression

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  1. Impulsive - occurs without thought and usually when the person is uncomfortable (e.g., feels hot);
  2. Retaliatory -occurs in response to provocation (such as a slap from another person);
  3. Instrumental- when a person aggresses to attain another goal, such as hitting in order to get a desired toy
  4. Angry - when the person experiences anger while aggressing. (Anderson, & Cusack, 2006)
  5. Relational Aggression - behaviour that cause harm or distress to others through the manipulation of relationships (Crick & Grotpeter, 1995). These behaviours can include but are not limited too; defamation, social exclusion and isolating or ignoring others.

Models of aggression[edit]

Research on aggressive behaviour and the explanations that accompany it have varied and changed over time. In modern day several theories that although differ, can also be arguably linked. These theories are psychoanalytic theory in that we have instincts and drives, that is it our subconscious controlling our aggression, and the social learning perspective in which we learn to behave the way we do from observation, experiences and circumstances (Tremblay, 2000)

Psychoanalytic Theory: refers to observable behaviours, those which can be measured and quantified, and consequences that follow such behaviours that characterise certain personality traits reflect underlying social structures of particular pathological features (Kernberg & Caligor, 1996). Psychoanalytic theory focuses on the inner struggle with one’s self, unconscious conflicts and if following a Freudian view deals with the id, ego and superego and his revised work that we succumb to two ruling instincts, the life instinct and the death instinct, Eros and the drive for the destruction of others or one’s self respectively (Sander, 2004). In identification with an aspect of the superego full recognition of the damage caused by childhood negative experiences, such as betrayal, allow expression of an individual’s aggression. Altering the superego to recognise and accept blocked parts of one’s own makeup and allow for self-forgiveness of the undesired negative traits that build deep relating characteristics in which the individual takes as part of their own from the betrayer, is suggested to help with the control of aggression (Lansky, 2009).

Social Learning Theory: suggests that behaviours are learned through observation and imitation. Individuals do not actually inherit violent tendencies but learn aggressive responses from observing others (Bandura, 1978). Social Learning Theory (SLT) suggests that learning is more likely to occur when models of behaviour are perceived as having more power, competence, higher status or are someone that is admired (Akers, 2000) SLT contends that behaviour is learned through imitation and reinforcement, leading to a series of definitions favourable to the behaviours (Akers, 2000) and because the violence is rewarded with compliance and dominance, those who engage in violence and aggression internalise and utilise the advantages of such methods. Children who observe or experience such negative exchanges learn behaviour to imitate in similar situations as well as rationales and motivations for using violence. (Hoffman et al., 2005)

-Social Cognitive Theory: is an extension of Social Learning Theory and states that learning, mental representation and interpretation are the pathways to aggression (Fiske, 2009). Social Cognitive Theory focuses on cognitive constructs such as interpersonal knowledge and attitudes that are believed to underlie aggression, specifically, people that are higher in aggressive behaviours will be higher in aggression-related cognitions.

-General Aggression Model: (Anderson & Bushman, 2002). This theory is the most comprehensive theory of Social Cognition in reference to aggression and states that these aggression-related cognitions are "knowledge structures": robust, interconnected concepts that are a representation of our knowledge about aggression, its attributes and how aggression relates to other concepts (Heussman, 1998). Knowledge structures are important to an individual as they contain normative beliefs, aggressive scripts and word schemas.

Frustration-Aggression Hypothesis: suggests that when we experience frustration, we experience anger and this anger is then directed at someone who is less powerful then us (Berkowitz, 1989)

Cognitive Neo-associationist Model: suggests that mental associations can lead to aggressive behaviour without any intervening representation of meaning (Berkowitz 2008). This is similar to classical conditioning in that our behaviour response has been conditioned to certain associations. Therefore unpleasant stimulus automatically stimulates thoughts, memories, expressive motor reactions and physiological responses associated with "fight or flight" mode. If the fight mode is activated aggressive behaviour will be pursued.

Excitation Transfer Model: suggests that physiological arousal dissolves slowly, so if an individual is aroused in one situation and another highly arousing situation occurs a short time later the arousal from the first situation may be misattributed to the second (Zillmann, 1983). Furthermore if aggression is present in the second situation the additional arousal will make the person even angrier than if the second event had occurred in isolation. This model also states that aggression is long lasting if the individual associates the heightened arousal to aggression. Therefore, even when the arousal is no longer present the individual will be ready to aggress.

Evolutionary/Biological Theories (drive for survival): suggests that aggression is necessary to adapt and survive. All human behaviour is a product of the mechanisms internal to an individual in combination with triggers that will activate those mechanisms. All of these mechanisms owe their existence to natural selection, as it is the only cause powerful enough to produce these mechanisms (Cosmides & Tooby, 1994). Wrangham and Glowacki (2012) state that humans fight when the risk is low, however when greater risks are taken it is due to the promise of cultural rewards or punishment that seem beneficial.

Causes of aggression[edit]

Situation- Centered Factors

Situational causes of aggression refer to external factors that influence aggressive behaviour. Four of the most studied situational causes relating to aggression are (Anderson, & Cusack, 2006):

(1) A verbal or physical attack

(2) frustration from feeling blocked or hindered in achieving goals - this can also include social disadvantage, socio-economic disadvantaged, road rage (someone going too slow will prevent you from getting to work on time) etc.

(3) Physical discomfort or pain - this can include uncomfortable temperatures, crowding or noise levels

(4) Exposure to violent media - video games are also included under this point, with much research being conducted on the effects of aggression and violent video games, and a lean towards a positive correlation. (Barlett, Harris and Baldassaro 2007)

-It should be noted that frustration effects are heightened when coupled with provocation. \

Person-centred Factors

Boys are more likely to engage in direct physical or verbal aggression. Girls are more likely to engage in indirect relational aggression. Also female aggression tends to be more hostile whilst male aggression in more instrumental (Anderson, & Cusack, 2006.)

The presence of an extra Y chromosome has shown to increase aggression in individuals. Similarly the decrease in oestrogen and progesterone (such as when women are menstruating) is likely to increase aggression (Anderson, & Cusack, 2006). As is an increase in testosterone.

Alcohol has been positively correlated with increase aggression. The more alcohol you consume the more likely you are to have aggressive tendencies throughout the inebriation including provocation, frustration and self-focused attention (Ito, Miller & Pollock 1996).

Personality traits

The five factor model (Costa & Mcrae, 1992) shows the five major personality dimensions. These are: Neuroticism, Extroversion, Conscientiousness, Agreeableness, and Openness to Experience. In relation to aggression neuroticism and agreeableness tend to be the stand out dimensions (Miller, Lynam & Leukefeld, 2003). Agreeableness refers to having good interpersonal relationships and care about the needs of others. Agreeableness involves a trusting, compliant nature, modesty and tenderness. Rating low on agreeableness and therefore high on antagonism means that individuals are hostile and irritable and feel the need to punish or attack with a disregard for others. Individuals rating high on neuroticism are hostile, impulsive, anxious, angry and prone to engage in irrational thought. The research suggests that these two dimensions will be the predictors for aggression levels in Individuals.

-The Big 5 personality test is available here. The Big 5

Personality Disorders

Borderline Personality Disorder - a core concept of this disorder is aggression against the self or others, with aggressive acts largely being of the impulsive type (Latlova, & Prasko, 2010)

Narcissistic Personality Disorder- characteristics include but are not limited too; vengeful rage in response to slight or injury, disproportionate anger when admiration is inadequate and extreme mood swings (Cooper, & Roningstam 1992)

Antisocial Personality Disorder - this personality disorder has traits including impulsivity, irritability and remorselessness (De Brito & Hodgins 1999)

-Concerned you may have a personality disorder? Take the test! Personality Test - [1]


Role of aggression[edit]

Buss and Shackleford,(1997) provide four evolutionary based roles of aggression:

(1)Aggression is an avenue taken in order to co-opt resources from others, this can occur at an individual level e.g. physical force, such as school bullies taking money from other children or at a group level e.g. a tribe taking over another tribes land and resources

(2)In response to this, aggression may then be used as a defence mechanism, whether it is to physically defend, build an aggressive reputation as a scare tactic or to prevent the loss of one’s status that would result in being victimised by aggressors.

(3)Inflicting costs on intrasexual rivals - Using direct or indirect aggression to derogate same-sex rivals, in order to make the self-seem more appealing, this is in the case of both males and females.

(4)Aggression may be used to attain power in one’s social hierarchy, whether this be by a boxer defeating his opponent or an aggressive business man climbing the ladder of a company. The aggressive individual continues to acquire status, power and respect. This is also the case for soldiers, these men aggressively fight on the battlefield and are seen as courageous and therefore have an increased status. Street gangs or mobs require aggression in order to be feared and ward off potential attackers. Although it should be noted that the use of aggression to elate status will not work in all groups, a student punching their professor will not get them a better grade or elated status among peers. Culture also plays a huge role, as cultural views towards aggression differ tremendously. E.g. European-American parents were far more disapproving of their daughter using aggression then were African-American parents (Blake, Lease, Turner & Olejnik 2010)

Aggressive behaviour is also a means by which people attempt to restore their damaged self-images [Feshbach, 1970]. This research has indicated that individuals who have unstable self-esteem are predisposed to high levels of aggression and hostility, in order to repair ones self-image or feelings of self-worth. The use of anger in a heated rational discussion can facilitate problem solving and communication in social situations and interpersonal relationships. (Parker, 2007)

However, If aggression only caused these positive effects then there would be no need to manage it, right? wrong. Problematic aggression can cause many problems in everyday life and relationships. If anger arousal occurs often and is unwarranted then problem solving and communication skills will be hindered in daily situations and relationships and therefore considered maladaptive. This form of anger becomes problematic when the goal of the anger is to be destructive, malice, selfish, harmful or vengeful. Problematic anger can compromise relationships and it also associated with high blood pressure, stroke and cardiovascular disease. Furthermore prolonged anger can increase the risk of depression and chronic pain by affecting the immune system in deactivating natural killer cells, and therefore increasing susceptibility to disease. (Parker, 2007) Problematic anger can result in the destruction of relationships and property, the loss of employment, criminal activity, physical/emotional harm to the self and others, poor communication skills, diminished respect etc. Therefore problematic aggressive tendencies need to be managed accordingly.

Management of aggressive tendencies[edit]

In the workplace

When managing aggression in the work place several steps need to be taken when dealing with an aggressive individual (DelBel, 2003). Firstly remain calm; speaking provocatively will only heighten the emotional arousal of the aggressor. Isolate the individual, when an aggressive individual is surrounded by a crowd they can feel empowered, or justified especially if no one steps in, an audience also makes the idea of backing off seem like a loss or failure. Be mindful of your body language, when dealing with an aggressive individual try not to get too close to them or make any gestures that could be interpreted as threatening. Be clear and simple in your communication; avoid the use of big words or jargon, complex messages that are hard to understand will increase the agitation felt by the individual. Use reflective questioning, rephrase the individual’s statement in your own words so that there is a complete understanding, this will also make the individual feel like you are listening. Embrace silence, this will allow the individual to clarify their thoughts and actions and may have a calming effect. Finally check your paraverbals (these refer to your tone, pace and rhythm of speech), two sentences that have the exact same wording can be taken in many different ways due to paraverbals.

In Children

When trying to manage a child’s aggression, Researchers have taken several paths. Firstly one should try to decrease the amount of direct (parents or friends) or indirect (media) exposure to aggression, or try to increase the amount of exposure children have with more competent pro-social models. Secondly, try to teach children that aggressive acts will be followed by punishment or negative consequences and the abstinence of such behaviours will be followed by rewards and positive outcomes. Finally, one should try to improve a child’s general social skills during a social conflict situation. This can be done by reducing hostile attribution biases. (Juan, 2005)

CBT framework

Psychological therapy for the individual

Cognitive behaviour therapy (CBT) – focusses attention to social cognition and individual interpretations of reality in modifying behaviour (Dodge, 1993). This type of therapy is the most common when managing problematic anger. CBT can combine or use individual techniques such as relaxation, cognitive restructuring, problem solving and coping skills through theories of learning and information processing (Beck & Fernendez, 1998). When focusing on anger a widely used CBT therapy is Stress Inoculation training, which allows individuals to focus on developing more effective communication skills to use during conflicts and has been found effective in decreasing negative expressions of anger (Parker, 2007). In order for this therapy to work individuals must first identify situational triggers that will set off their anger. After this identification has been made, individuals are instructed to rehearse statements that positively re-frame the situation and therefore elicit a positive response. Next individuals are taught relaxation skills, and are then presented with the trigger and instructed to couple the relaxation skills with the self-statements. Finally during the rehearsal stage individuals are continuously provoked and asked to practice their skills until the appropriate mental and physical responses become automatic (Beck & Fernendez, 1998).

Pharmacological therapy (drug use) (Conlond, P., Frommhold, K 1989)

Only used in patients with severe aggression or mental/personality disorders relating in aggression

Neuroleptics – used for people with psychotic symptoms such as delusional thinking associated with aggressive acts. Neuroleptics are also used in the case of emergencies when reasons for behaviour are undetermined and the individual needs to be sedated. However it is not advised that these drugs be used at high doses or for extended periods of time as they have produced an increase in morbidity rates for users.

Beta-Blockers - control assaultive and enraged behaviour by decreasing the over activity of the central nervous system norepinephrine. However the effects of this drug can lead to an increase risk of cardiac arrest and therefore candidates for this drug must undergo a through medical test and the cost-benefits be weighed.

Lithium - reduces aggression related to manic elation, and irritability associated with cyclicyc affective disorder. Trials have also shown lithium to be helpful in aggression unrelated to an affective disorder such as mental retardation, head injury and antisocial personality disorder. Caution must be taken when using on patients with epilepsy.

Benzodiazepines – useful in the treatment of aggressive patients whom are not psychotic, and should only be used in the absence of psychotic symptoms.

General

Anger management programs are diverse in course content, format, number of sessions, and theoretical orientations. Today, most anger management programs provide instruction in the art of relaxation, problem-solving skills, and cognitive-behavioural strategies focused on changing thoughts and maladaptive behavioural responses.They are designed to teach participants problem solving skills, incorporating conflict resolution techniques, communication training, self-monitoring, personality assessments and self exploration. Reducing an individual degree of ego involvement through mindfulnessis one way to decrease aggressive behaviours. Mindfulness is defined as a moment-to-moment awareness (Kabat-Zinn, 2003) in that we are being deliberately aware of the present point in time, this allows people to experience the present without evaluation or defence. Therefore positive or negative events are not attached to the self yet taken at face value as something that has just happened. It is further suggested that mindfulness results in the individual altering their openness to experience which is an independent function that decreases cognitive defensiveness (Hodgins & knee 2002)

People may use both conscious and unconscious mechanisms to manage their anger. The three main approaches (Spielberger1, Reheiser1 & Sumner 1995) are expressing, suppressing and calming. Expressing ones anger is the healthiest way to relieve one's anger, however this must be done in an assertive way not an aggressive way, being assertive is not being violent or demanding it making your needs clear and being respectful of yourself and others. Suppression can be a dangerous technique, as suppressing an emotion such as anger can cause an individual high blood pressure, hypertension or depression. Healthy suppression involves converting and redirecting that anger to more constructive behaviour. Finally an individual can try to calm them self down, this not only refers to possible behavioural responses but also calming your internal responses, such as slowing your heart rate or breathing pace. Some self strategies and individual can implement are deep breathing, visualizing a relaxing place, slowly repeating calming words or phrases or practicing Yoga-like exercises to relax the muscles for a calm feeling.


Hopefully, future programs will be able to tailor anger management programs for each participant rather than providing a generic program.For further strategies in managing anger please visit apa anger control

It is important to remember when anger remains unexpressed, other issues can arise. An individual can develop a perpetually cynical and hostile personality (Holt, 1970). Furthermore it can also lead to passive-aggressive behavior (getting back at people indirectly, without telling them why, rather than confronting them head-on). People who are constantly vengeful, indirect, putting others down and criticizing everything, haven not learned how to constructively express their anger. Not surprisingly, these type of people are not likely to acquire or maintain many successful interpersonal relationship relationships.

Conclusion[edit]

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Aggression plays a major role in everyday life. Aggression is only negative when the behaviour elicited becomes destructive, vengeful and impulsive. Aggression expressed in a healthy manner can improve communication, problem solving, interpersonal relationships and help to achieve individual goals and desires. The role of aggression in this sense is crucial, as unexpressed anger can internalize and cause health problems for the individual. Risk factors for acquiring problematic aggression include gender, hormone levels, environmental cues personality disorders and traits. It is important to be aware of where you stand in relation to these risk factors and monitor your aggression accordingly. For example if you are feeling irrationally angry but are aware that your menstrual cycle is about to start then you know your anger may be attributed to hormonal changes. If this is the case then self-calming techniques should be implemented as well as constructive expressions of your feelings through communication. If you notice that you only get aggressive after you have been drinking then an individual needs to modify their own behaviour (stop consuming alcohol) in order to resolve the problem. However if you find yourself to be constantly aggressive and maladaptive one should seek professional help and undergo CBT or in extreme cases, the use of drugs. The social learning theory suggests that our aggressive tendencies are learned throughout childhood, so it is important to note how much violence/aggression your child is indirectly or directly exposed too. If aggressive behaviour is present techniques need to be implemented to ensure the child deters away from this behaviour.

Remember aggression is healthy! We just need to learn how to express it constructively, not destructively.

See also[edit]

Mindfulness

assertiveness

Yoga and emotion

testosterone and emotion

References[edit]

Akers, R. L. (2000). Criminological theories: introduction, evaluation, and application, 3rd ed. Los Angeles, CA: Roxbury

Anderson, C. A., & Bushman, B. J. (2002). human aggression. Annual Review of Psychology, 53, 27-51

Anderson, K. B. & Cusack, R. (2006) Aggression: Encyclopedia of Human Development, 1, 152-59

Barlett. C., Harris, R. & Baldassaro, R. (2007) Longer you play, the more hostile you feel:examination of first person shooter video games and aggression during video game play. Aggressive Behaviour, 33, 6, 486- 97

Beck, R., & Fernendez, E. (1998). Cognitive-Behavioural therapy in the treatment of anger: a meta analysis. Cognitive Therapy and Research, 22, 1, 63-74

Berkowitz, L., (1989) the frustration – aggression Hypothesis: Examination and Reformulation. Psychologcal Bulletin, 106, 1, 59-73

Berkowitz L. (2008). On the consideration of automatic as well as controlled psychological processes in aggression. Aggressive Behaviour, 34, 117–129.

Blake, J. J., Lease, A., M., Turner, T. L. & Olejnik, S. P. (2010) Ethnic differences in parents attitudes’ towards girls’ use of aggression: Journal of Aggression, Maltreatment and Trauma, 19, 4, 393-413

Buss, D. M., Shackleford, T. K., (1997) Human aggression in evolutionary psychological perspective. Clinical Psychology Review, 17, 6, 605-619

Conlond, P., Frommhold, K (1989)Aggression: Psychopharmocolig management: Canadian Family Physician, 35, 1135-1138

Cooper, A. M., & Roningstam, E. (1992) Narcissistic personality disorder: Review of Psychiarty, 11, 5, 80-98

Costa, P. T., & McCrae, R. R. (1992). Revised NEO-Personality Inventory (NEO-PI-R) and NEO Five-Factor Inventory (FFI) manual. Odessa, FL: Psychological Assessment Resources.

Crick, N. R. & Grotpeter, J. K. (1995). Relational aggression, gender and social-psychological adjustment. Child Development, 66, 710-722

De Brito, S. A., & Hodgins, S. (2009) Antisocial personality disorder: Personality, Personality Disorder and Violence: An Evidence Based Approach, 7, 133-138

DelBel, J. (2003). De-escalating workplace aggression. Nursing Management, 34, 9, 31-34

Dodge, K. A. (1993). Social cognitive mechanisms in the development of conduct disorder and depression. Annual Review of Psychology, 44, 559-584

Feshbach S. 1970. Aggression. In: Mussen PH (ed.). Carmichael’s Manual of Child Psychology. Vol. 2. New York: Wiley, pp 159–259

Fiske, S. T. (2009). Social beings: Core motives in social psychology (2nd ed.). new York, nY: Wiley

Holt, R. (1970) On the interpersonal and intrapersonal consequences of expressing or not expressing anger. Journal of Consulting and Clincial Psychology, 35, 1, 8-12

Hodgins, H. S., Knee, C. R., (2002) The intergrating self and conscious experience. In Deci EL, Ryan RM (eds.). Handbook of self-determination research. New York: University of Rochester Press, pp 87-100

Huesmann, l. R. (1998). the role of social information processing and cognitive schema in the acquisition and maintenance of habitual aggressive behavior. in r. G. Geen & e. i. Donnerstein (eds.), Human aggression: Theories, research, and implications for social policy (pp. 73-110). san Diego, CA: Academic Press.

Ito, T. A., Miller, N., Pollock, V. E. (1996) Alcohol and aggression: A meta-analysis on the moderating effects of inhibitory cues, triggering events, and self-focused attention. Psycholigcal Bulletin, 120, 1, 60-82

Juan, F. (2005) Aggression: Encyclopaedia of Applied Developmental Science, 1, 62-66

Kabat-Zinn J. 2003. Mindfulness-based interventions in context: Past, present, and future. Clinical Psychology, 10, 144–156.

Kernberg, O.F. & Caligor, E. (1996). A psychoanalytic theory of personality disorders. Major Theories of Personality Disorder, 3, 114-126

Lansky, M.R. (2009). Prologue. Psychoanalytic Inquiry, 29, 5, pp 357-361

Latalova, K., Prasko J. (2010) Aggression in Borderline Personality Disroder. Psychiatric Quarterly, 81, 3, 239-251

Miller, J. D., Lynam, D., & Leukefeld, C. (2003) Examining antisocial behaviour through the five-factor model of personality. Aggressive Behvaiour, 29, 497-514

Parker, V. H. (2007). The comparative efficacy of CBT versus CBAT for the treatment of problematic anger. (Order No. 1442834, Southern Methodist University). ProQuest Dissertations and Theses, 54.

Sander, F.M. (2004). Psychoanalytic Couple Therapy: Classical Style. Psychoanalytic Inquiry, 24, 3, pp. 373-386

Spielberger, C. D. Reheiser, E. C. & Sumner, J. S. (1995) Measuring the Experience, Expression, and Control of Anger. Issues in Comprehensive Paediatric Nursing, 18,3, 207-232

Tremblay R.E. (2000) The development of aggressive behaviour during childhood: What have we learnt over the past century. International Journal of Behavioural Development, 24, 2, pp. 129-141

Wrangham, R. W., Glowacki, L. (2012) Intergroup aggression in chimpanzees and war in nomadic hunter gatherers: evaluating the chimpanzee model. Human Nature, 23 (1), doi:10.1007/s12110-012-9132-1

Zillmann D. 1988. Cognition- excitation interdependencies in aggressive behaviour: Aggressive Behaviour, 14, 51-64

External links[edit]

Personality disorder test

The Big 5

Anger Control