Aggression: any form of behaviour that is intended to injure someone physically or psychologically. Violence: when aggression is intended to cause extreme injury. Hostile aggression: arises out of negative emotions such as anger and frustration. Instrumental aggression: motivated by goals other than harming the target- either teaching a lesson or to steal something of value. More often premeditated than impulsive: e. g. spanking your child, or knocking someone over to steal their bag. Behaviour that is intended to damage another person"s peer relationships. Studies show that boys engage in more overly physical aggression vs. girls who engage in more relational behaviour studies done by preschool kids; shows how early behaviours are taught. Aggressive behaviour is also associated with popularity; seen as cool and leads to peer acceptance rather than rejection. Corporal punishment: inflicting pain without sustaining injury (spanking: only effective for short-term compliance, correlates to greater aggression, lower mental health, and parental relationship in the future.