According to Robert Agnew, the general strain theory states that people under tension or stress become angry, which can lead them to commit a crime. Tension “is the direct result of negative affective states” (Siegel 153). Sources of tension are the failure to achieve positive goals due to lack of resources, the disjunction between results and expectations, the lack of positively valued stimuli, and the presence of negative stimuli. The person who fails to get what he wants or encounters obstacles experiences negative emotions such as fear, disappointment, depression and even anger. This anger produces a desire for revenge, which results in violence and aggression. Agnew suggests that there are other sources of strain that can affect a person significantly, such as family break-ups, unemployment, moving, dropping out of school, and unwanted events.