Supposed links between fictional and actual violence
The study of violence in mass media analyzes the degree of correlation between themes of violence in media sources (particularly violence in video games, television and films) with real-world aggression and violence over time.
Many social scientists support the correlation, however, some scholars argue that media research has methodological problems and that findings are exaggerated. Other scholars have suggested that the correlation exists, but can be unconventional to the current public belief.
Complaints about the possible detrimental effects of mass media appear throughout history; Plato was concerned about the effects of plays on youth. Various media/genres, including dime novels, comic books, jazz, rock and roll, role playing/computer games, television, films, internet (by computer or cell phone) and many others have attracted speculation that consumers of such media may become more aggressive, rebellious or immoral. This has led some scholars to conclude that statements made by some researchers merely fit into a cycle of media-based moral panics. The advent of television prompted research into the effects of this new medium in the 1960s. Much of this research has been guided by social learning theory, developed by Albert Bandura. Social learning theory suggests that one way in which human beings learn is by the process of modeling. Another popular theory is George Gerbner's cultivation theory, which suggests that viewers cultivate a lot of violence seen on television and apply it to the real world. Other theories include social cognitive theory, the catalyst model, and moral panic theory. 
Media effects theories.
Social learning theory.
Social learning theory was proposed by Albert Bandura and suggests that people learn by observing the outcome of others' actions, and that meritable actions were more likely to be imitated than punishable ones. The behavior was observed in Bandura's Bobo Doll experiments. Bandura presented children with an Aggressive Model: The model played with 'harmless' tinker toys for a minute or so but then progressed onto the Bobo doll, in which the model laid the doll down and was violent toward it (punched its nose, hit it with a mallet, tossed it in the air, and kicked it). In addition, verbal comments were made in relation to the scenario. They then put the children in a room with a Bobo doll to see if he/she would imitate the behavior previously seen on the video.
The findings of this experiment suggest that children tended to model the behavior they witnessed in the video. This has been often taken to imply that children may imitate aggressive behaviors witnessed in media. However, Bandura's experiments have been criticized on several grounds. First, it is difficult to generalize the aggression toward a bo-bo doll (which is intended to be hit) to person-on-person violence. Secondly, it may be possible that the children were motivated simply to please the experimenter rather than to be aggressive. In other words, the children may have viewed the videos as instructions, rather than incentives to feel more aggressive. Third, in a later study Bandura included a condition in which the adult model was punished for hitting the bo-bo doll by himself being physically punished. Specifically the adult was pushed down in the video by the experimenter and hit with a newspaper while being berated. This actual person-on-person violence actually decreased aggressive acts in the children, probably due to vicarious reinforcement. Nonetheless these last results indicate that even young children don't automatically imitate aggression, but rather consider the context of aggression. Children with aggression have difficulty communicating compassionately. 
Social Learning Theory and "Teen Gamers".
Over time, "teen gamers" can become unaware of their surroundings and lack social interaction in real life. According to the article by Hygen Beate in 2019 mention the video game violence can impact an individual's essential social skills such as their emotions, behavior towards others, listening and understanding ability, responding or communicating, knowing verbal and non-verbal cues, sharing their thoughts, and cooperating with others. According to the survey in medical journal JAMA Network Open written by Chang published May 31, 2019, kids who repeatedly played violent video games learned to think viciously that could eventually influence their behavior and cause them to become aggressive in nature.
Given that some scholars estimate that children's viewing of violence in media is quite common, concerns about media often follow social learning theoretical approaches.
Social cognitive theory.
Social cognitive theories build upon social learning theory, but suggest that aggression may be activated by learning and priming aggressive scripts. Desensitization and arousal/excitation are also included in latter social cognitive theories. The concept of desensitization has particularly gotten much interest from the scholarly community and general public. It is theorized that with repeated exposure to media violence, a psychological saturation or emotional adjustment takes place such that initial levels of anxiety and disgust diminish or weaken. For example, in a study conducted in 2016, a sample of college students were assigned at random to play either a violent or non-violent video game for 20 minutes. They were then asked to watch a 10-minute video of real life violence. According to the American Psychological Association's report titled technical report on the review of the violent video game literature written by Caldwell in February 2020, the revision to the 2015 resolution, playing video games, is often popularly associated with adolescence. "Children younger than age eight who play video games spend a daily average of 69 minutes on handheld console games, 57 minutes on computer games, and 45 minutes on mobile games, including tablets." The students who had played the violent video games were observed to be significantly less affected by a simulated aggressive act than those who did not play the violent video games. However, the degree to which the simulation was "believable" to the participants, or to which the participants may have responded to "demand characteristics" is unclear (see criticisms below). Nonetheless, social cognitive theory was arguably the most dominant paradigm of media violence effects for many years, although it has come under recent criticism. Recent scholarship has suggested that social cognitive theories of aggression are outdated and should be retired. Some scholars also argue that the continuous viewing of violent acts makes teenagers more susceptible to becoming violent themselves. Children of young age are good observers; they learn by mimicking and adapting the behavior. Playing violent video games created a fear in everyone's heart of violence in real life, which was only valid for adolescents with underlying psychological problems. According to the journal article written by McGloin in 2015, media violence can trigger aggressive behavioral change in the highly characterized aggressive individual. An individual can face severe consequences with media violence, which can increase "bullying behavior."
Cultivation theory.
This theory was created by George Gerbner as an alternative way to look at the correlation of violence as seen on television and the individual. Gerbner describes the violence seen on television that most of the population was viewing as "happy violence". He called it such because he noticed that most of the violence seen on television was always followed by a happy ending. Gerbner gave this importance as he believed that the world does not contain 'happy violence' as sometimes there is violence for no reason. However, because the violence seen on television is so captivating for viewers. Gerbner believes that the population will think that violence, whether fictional in movies and shows or non-fictional from the news, will directly effect them. Gerbner named this theory the "magic bullet theory". This theory described the violence seen on television as a "magic bullet" that reaches beyond the screen right into every individual viewer. After this occurs, cultivation theory begins when the individual begins to develop a perception of real world violence around them. Over time, consumers of media will cultivate the violence seen on television and will consider this to be how the real world actually is. This leads to assumptions of local and national crime rates increasing when they are actually decreasing. Additionally, this will lead to negative assumptions about certain groups as they are mainly shown to be violent on television. The main example being illegal immigrants coming from Mexico into the United States. Frequent news watcher will view cases of violent crimes conducted by illegal immigrants. This leads them to believe that all illegal immigrants act this way, thus leading to their disapproval of them. Gerbner calls this the "Mean World Syndrome" which is the product of all the previous theories, stating that a viewer will eventually believe that they live in a world full of deviance and aberrancy.
Catalyst model.
One alternative theory is the catalyst model which has been proposed to explain the etiology of violence. The catalyst model is a new theory and has not been tested extensively. According to the catalyst model, violence arises from a combination of genetic and early social influences (family and peers in particular). According to this model, media violence is explicitly considered a weak causal influence. Specific violent acts are catalyzed by stressful environment circumstances, with less stress required to catalyze violence in individuals with greater violence predisposition. Some early work has supported this view Research from 2013 with inmates has, likewise, provided support for the catalyst model. Specifically, as suggested by the catalyst model, perpetrators of crimes sometimes included stylistic elements or behaviors in their crimes they had seen in media, but the motivation to commit crimes itself was unrelated to media viewing and instead internal.
Moral panic theory.
A final theory relevant to this area is the moral panic. Elucidated largely by David Gauntlett, this theory postulates that concerns about new media are historical and cyclical. In this view, a society forms a predetermined negative belief about a new medium—typically not used by the elder and more powerful members of the society. Research studies and positions taken by scholars and politicians tend to confirm the pre-existing belief, rather than dispassionately observe and evaluate the issue. Eventually the panic dies out after several years or decades, but ultimately resurfaces when yet another new medium is introduced.
General aggression model.
The general aggression model (GAM) proposed by Craig A. Anderson and Brad Bushman is a meta-theory that examines the role of situational and personal variables on behaviors that are aggressive varying from biological to cultural. Variables stem from one's internal states (feelings, thoughts, arousal) and the appraisal/decisions one makes (both automatic and controlled). The GAM was not originally not made to be used as a model to account for media violence, but as a general model for aggressive behavior. By focusing on the general media violence effects, both short and long-term effects, and the recent developments in media violence exposure and its pathways to short and long-term effects, one can use the GAM to account for media violence effects.
Since the GAM is a bio-social-cognitive model, it can explain how both media violence and social environment shape behavior. A study researched how brain structure can add to the GAM and processing. Fast-paced technology, such as video games and television, change brain structure in parts of the brain that are associated with executive control and impulse control. Moreover, social environment is an important piece of the GAM. Because a media diet is part of a social environment, media violence can effect processing. 
Two-step flow theory.
Paul Lazarsfeld created this theory in 1944. Two-step flow theory opposes the notion that the effect of mass media is a direct one. Instead, it suggests that the information and ideas coming from the mass media go to people named the opinion leaders. Opinion leaders gather the information they hear, make sense of it, and develop a narrative that they would like to push. The opinion leaders would then share their views and ideas with the general public, who then take on the role of Opinion followers. Mass media can give information to many different opinion leaders that will disseminate information in their own unique way, and will then gain a following of opinion followers that will believe their specific outlook on the information. This can lead to many different groups that believe similar or vastly different things that all began at the same source. A popular example of this is news outlets that have political biases. A conservative news source will disseminate information that is typically more accepted and followed by a conservative viewership, and the same goes for more liberal news outlets that have a much more liberal following.