Aggressive behavior is commonly defined as behavior that is intended to physically or psychologically hurt another person (or oneself) or to damage or destroy property. Aggressive behavior is a characteristic of an at-risk child. It is argued by some that for a behavior to be termed aggressive the aggressor must feel anger or hostility toward the "victim" and must derive satisfaction from hurting the victim. This kind of aggression is called hostile aggression. In contrast to hostile aggression, there can be cases where the aggressor is interested only in getting an object from the victim or achieving a goal. This is called instrumental aggression, and need not involve anger or hostility (Bentzen, 2005).
Many young children, including children with disabilities, engage in behaviors that are labeled as "challenging", "aggressive" or "at-risk". In many cases, aggressive behavior is short term and decreases with age with the use of appropriate strategies. As children increase their physical mobility and cognitive competence usually around l5 months of age they are more able to discover their environment. They begin to interact more with their peers, and their playtime with their peers' increases as well. During this period physical aggression tends to occur more frequently. It is during this stage that children learned they can hurt others and they themselves can be hurt. The conflicts that occur during this stage are normally over the possession of an object such as a toy.
Aggressive behavior can occur in a variety of forms such as: slapping, grabbing, screaming, pinching, kicking, spitting, biting, or a variety of other actions. Aggression can also be verbal or non verbal. Working with Early Head Start 0-3 years of age and other private preschool programs the aggressive behavior displayed are usually in a physical form. This particular behavior is defined as instrumental aggression, with the majority of outburst happening in fights over toys.