|Title of host publication||Encyclopedia of media violence|
|Editors||Matthew S Eastin|
|Place of Publication||Thousand Oaks, California|
|Number of pages||5|
|Publication status||Published - 2014|
There is yet to be universal acceptance of any one definition of aggression; however, researchers in the field of psychology have tended to broadly agree that aggression is a behavior (which could be physical, verbal, relational/social, direct, or indirect) performed with the intent to hurt another who does not want to be hurt. Acts of aggression can be assessed in many ways, with laboratory experiments examining the willingness to hurt another in a controlled environment, questionnaire research asking about one’s own or another’s aggressive behavior, field research taking observational notes of aggression seen in everyday situations, and brain-scanning research examining changes to the brain associated with aggression. Crucially, each form of assessing aggression has unique strengths and weaknesses, leading to controversy about whether aggression has been truly measured in each case. The best evidence that something causes aggression comes from converging evidence from all types of assessment, each of which can overcome the shortcomings of another. This entry first examines how aggression is defined and categorized, and then examines these four types of aggression assessment that are commonly used in media violence research, describing the strengths and weaknesses of each, noting the assessment methods used, and providing examples.