Aggression
Some scholars believe that behaviors like aggression may be partially learned by watching and imitating people's behavior, while other researchers have concluded that the media may have some small effects on aggression. There is also research questioning this view. For instance, a long-term outcome study of youth found no long-term relationship between playing violent video games and youth violence or bullying. One study suggested there is a smaller effect of violent video games on aggression than has been found with television violence on aggression. This effect is positively associated with type of game violence and negatively associated to time spent playing the games. The author concluded that insufficient evidence exists to link video game violence with aggression. However, another study suggested links to aggressive behavior.
Psychology of learning
Edward Thorndike (1874–1949) presented his theory of the "Law of Effect" in 1898. According to this theory, humans and other animals learn behaviors through trial-and-error methods. Once a functioning solution is found, these behaviors are likely to be repeated during the same or similar task. It was his work on learning theory that resulted in operant conditioning within behaviorism. His theory of operant conditioning is learning from the consequences of our actions and behavior. 
Ivan Petrovich Pavlov (1849–1936) was a Russian physiologist, who contributed to research on learning. Knowing that a hungry dog salivates when food is present, he performed a series of experiments and trained dogs to salivate through an arbitrary external stimuli. This was done by pairing natural stimuli (such as food) with a new stimulus (e.g., a metronome) to provoke the desired response in dogs. That proved his thesis that he could make a dog salivate by just the presentation of the sound of a bell. Pavlov's approach to learning was behavioristic and later known as classical conditioning.