(1995). Developmental social psychology. Massachusetts: Blackwell. [Chapter 12: "The development of aggression" .pp 397).
Aggression can arise because of certain chemical influences, such as serotonin and testosterone. A lack of serotonin will cause the individual to be more aggressive and a surplus of testosterone will also cause the individual to be more aggressive. This can be shown by the findings of James Dabbs and his colleagues in which they found that there were far higher levels of testosterone in prisoners convicted of violent crimes than prisoners convicted of non-violent crimes (Aronson, E., Wilson, T.D. & Akert, R.M. (2002). Social psychology 4th edition. New jersey: Prentice-Hall. [Chapter 12: "Aggression: Why we hurt other people" pp.417]). Alcohol can be another cause of aggression. Alcohol disrupts the individual from processing information properly thus many misunderstandings can arise in which aggressive behaviour may be shown. Drunken people tend to respond more violently to provocations than sober people (Bushman, 1993; Lipsey, Wilson, Cohen, & Derzon, 1997; Taylor and Leonard, 1983).
One of the most important factors that can cause aggression is television. Television programs today contain a large amount of violence and sex and with the average child watching two to four hours of television a day (Huston & Wright, 1996), the child will experience copious amounts of murders and sex scenes. Studies indicate that this long-term exposure of violence and sex shown on television causes the individual to exhibit violence and aggression later on in their lives (Eron, 1982, 1987; Eron, Huesmann, Lefkowitz, & Walder, 1996; Huesmann, 1982; Huesmann & Miller, 1994; Turner, Hesse, & Peterson-Lewis, 1986). With all this exposure to violence aggressive behaviour can be explained with five reasons.