Aggression is behavior aimed at opposing or attacking something or someone. Though often done with the intent to cause harm, some might channel it into creative and practical outlets. It may occur either reactively or without provocation. In humans, aggression can be caused by various triggers. For example, aggression may result from built-up frustration due to blocked goals or perceived disrespect. Human aggression can be classified into direct and indirect aggression; while the former is characterized by physical or verbal behavior intended to cause harm to someone, the latter is characterized by behavior intended to harm the social relations of an individual or group.
In definitions commonly used in the social sciences and behavioral sciences, aggression is an action or response by an individual that delivers something unpleasant to another person.Buss, A. H. (1961). The psychology of aggression. Hoboken, NJ: John Wiley. Some definitions include that the individual must intend to harm another person.
In an interdisciplinary perspective, aggression is regarded as "an ensemble of mechanisms formed during the course of evolution in order to assert oneself, relatives, or friends against others, to gain or to defend resources (ultimate causes) by harmful damaging means. These mechanisms are often motivated by emotions such as fear, frustration, anger, stress, dominance or pleasure (proximate causes). Sometimes aggressive behavior serves as a stress relief or a subjective feeling of power." Predatory or defensive behavior between members of different species may not be considered aggression in the same sense.
Aggression can take a variety of forms, which may be expressed physically, or communicated verbally or non-verbally, including: anti-predator aggression, defensive aggression (fear-induced), predatory aggression, dominance aggression, inter-male aggression, resident-intruder aggression, maternal aggression, species-specific aggression, sex-related aggression, territorial aggression, isolation-induced aggression, irritable aggression, and brain-stimulation-induced aggression (hypothalamus). There are two subtypes of human aggression: (1) controlled-instrumental subtype (purposeful or goal-oriented); and (2) reactive-impulsive subtype (often elicits uncontrollable actions that are inappropriate or undesirable). Aggression differs from what is commonly called assertiveness, although the terms are often used interchangeably among laypeople (as in phrases such as "an aggressive salesperson").Akert, R.M., Aronson, E., & Wilson, T.D. (2010). Social Psychology (7th ed.). Upper Saddle River, NJ: Prentice Hall.
Overview Dollard et al. (1939) proposed that aggression was due to frustration, which was described as an unpleasant emotion resulting from any interference with achieving a rewarding goal. Berkowitz extended this frustration–aggression hypothesis and proposed that it is not so much the frustration as the unpleasant emotion that evokes aggressive tendencies, and that all aversive events produce negative affect and thereby aggressive tendencies, as well as fear tendencies. Besides conditioned stimuli, Archer categorized aggression-evoking (as well as fear-evoking) stimuli into three groups; pain, novelty, and frustration, although he also described looming, which refers to an object rapidly moving towards the visual sensors of a subject, and can be categorized as "intensity."
Aggression can have adaptive benefits or negative effects. Aggressive behavior is an individual or collective social interaction that is a hostile behavior with the intention of inflicting damage or harm. Two broad categories of aggression are commonly distinguished. One includes affective (emotional) and hostile, reactive, or retaliatory aggression that is a response to provocation, and the other includes instrumental, goal-oriented or predatory, in which aggression is used as a means to achieve a goal.Berkowitz, L. (1993). Aggression: Its causes, consequences, and control. New York, NY: McGraw-Hill. An example of hostile aggression would be a person who punches someone that insulted him or her. An instrumental form of aggression would be armed robbery. Research on violence from a range of disciplines lend some support to a distinction between affective and predatory aggression. However, some researchers question the usefulness of a hostile versus instrumental distinction in humans, despite its ubiquity in research, because most real-life cases involve mixed motives and interacting causes.
A number of classifications and dimensions of aggression have been suggested. These depend on such things as whether the aggression is verbal or physical; whether or not it involves relational aggression such as covert bullying and social manipulation;Ellie L. Young, David A. Nelson, America B. Hottle, Brittney Warburton, and Bryan K. Young (2010) Relational Aggression Among Students Principal Leadership, October, copyright the National Association of Secondary School Principals whether harm to others is intended or not; whether it is carried out actively or expressed passively; and whether the aggression is aimed directly or indirectly. Classification may also encompass aggression-related emotions (e.g., anger) and mental states (e.g., impulsivity, hostility). Aggression may occur in response to non-social as well as social factors, and can have a close relationship with stress coping style. Aggression may be displayed in order to intimidate.
The operative definition of aggression may be affected by moral or political views. Examples are the axiomatic moral view called the non-aggression principle and the political rules governing the behavior of one country toward another. Likewise in competitive sports, or in the workplace, some forms of aggression may be sanctioned and others not (see Workplace aggression).Nathaniel Snow Violence and Aggression in Sports: An In-Depth Look (Part One) (Part 2 Part 3) Bleacher Report, 23 March 2010 Aggressive behaviors are associated with adjustment problems and several psychopathological symptoms such as antisocial personality disorder, borderline personality disorder, and intermittent explosive disorder.
Biological approaches conceptualize aggression as an internal energy released by external stimuli, a product of evolution through natural selection, part of genetics, and a product of hormonal fluctuations. Psychological approaches conceptualize aggression as a destructive instinct, a response to frustration, an affect excited by a negative stimulus, a result of observed learning of society and diversified reinforcement, and a result of variables that affect personal and situational environments.
Etymology The term aggression comes from the Latin word aggressio, meaning attack. The Latin was itself a joining of ad- and gradi-, which meant "step at". The first known use dates back to 1611, in the sense of an unprovoked attack.Merriam-Webster: Aggression Retrieved 10 January 2012
A psychological sense of "hostile or destructive behavior" dates back to a 1912 English translation of Sigmund Freud's writing.Online Etymology Dictionary: Aggression Retrieved 10 January 2012 Alfred Adler theorized about an "aggressive drive" in 1908. Child raising experts began to refer to aggression, rather than anger, from the 1930s.Stearns, D. C. (2003). Anger and aggression. Encyclopedia of Children and Childhood: In History and Society. Paula S. Fass (Ed.). Macmillan Reference Books
Ethology
Ethologists study aggression as it relates to the interaction and evolution of animals in natural settings. In such settings aggression can involve bodily contact such as biting, hitting or pushing, but most conflicts are settled by threat displays and intimidating thrusts that cause no physical harm. This form of aggression may include the display of body size, antlers, claws or teeth; stereotyped signals including facial expressions; vocalizations such as bird song; the release of chemicals; and changes in coloration.Van Staaden, M.J, Searcy, W.A. & Hanlon, R.T. 'Signaling Aggression' in Aggression Academic Press, Stephen F. Goodwin, 2011 The term agonistic behavior is sometimes used to refer to these forms of behavior.
Most ethologists believe that aggression confers biological advantages. Aggression may help an animal secure territory, including resources such as food and water. Aggression between males often occurs to secure mating opportunities, and results in selection of the healthier/more vigorous animal. Aggression may also occur for self-protection or to protect offspring. Aggression between groups of animals may also confer advantage; for example, hostile behavior may force a population of animals into a new territory, where the need to adapt to a new environment may lead to an increase in genetic flexibility.Psychology- The Science of Behaviour, pg 420, Neil R Clarkson (4th Edition)
Between species and groups The most apparent type of interspecific aggression is that observed in the interaction between a predator and its prey. However, according to many researchers, predation is not aggression. A cat does not hiss or arch its back when pursuing a rat, and the active areas in its hypothalamus resemble those that reflect hunger rather than those that reflect aggression.Gleitman, Henry, Alan J. Fridlund, and Daniel Reisberg. Psychology. 6th ed. New York: W W Norton and Company, 2004. 431–432. However, others refer to this behavior as predatory aggression, and point out cases that resemble hostile behavior, such as mouse-killing by rats. In aggressive mimicry a predator has the appearance of a harmless organism or object attractive to the prey; when the prey approaches, the predator attacks.
An animal defending against a predator may engage in either "fight or flight" or "tend and befriend" in response to predator attack or threat of attack, depending on its estimate of the predator's strength relative to its own. Alternative defenses include a range of antipredator adaptations, including alarm signals. An example of an alarm signal is Nerol, a chemical which is found in the mandibular glands of Trigona fulviventris individuals. Release of Nerol by T. fulviventris individuals in the nest has been shown to decrease the number of individuals leaving the nest by fifty percent, as well as increasing aggressive behaviors like biting. Alarm signals like nerol can also act as attraction signals; in T. fulviventris, individuals that have been captured by a predator may release nerol to attract nest mates, who will proceed to attack or bite the predator.
Aggression between groups is determined partly by willingness to fight, which depends on a number of factors including numerical advantage, distance from home territories, how often the groups encounter each other, competitive abilities, differences in body size, and whose territory is being invaded. Also, an individual is more likely to become aggressive if other aggressive group members are nearby. One particular phenomenon – the formation of coordinated coalitions that raid neighboring territories to kill conspecifics – has only been documented in two species in the animal kingdom: 'common' chimpanzees and humans.
Within a group