Volume index - Journal index - Article index - Map ---- Back

Comunicar Journal 37: The University Network and on the Net (Vol. 19 - 2011)

The Risk of Emergence of Boomerang Effect in Communication against Violence


Gaspar Brändle Señán

Miguel Ángel Martín-Cárdaba

José Antonio Ruiz San Román


Violent behaviors cause concern among people, policy makers, politicians, educators, social workers, parents associations, etc. From different fields and perspectives, measures are taken to try to solve the problem of violence. Institutional communication campaigns against violence and the publication of news related to violent events are often some of the actions used by policy makers. But some of the literature and data have shown that its effectiveness is not always exactly as expected. And even some anti-violence messages, can have the opposite effect and reinforce the attitudes of those who thought that violence is necessary. The hypothesis is that most people assume with no problem the core message of anti-violence campaigns. But, and this is the key issue and most problematic, individuals who are more likely to be violent (precisely those who should address such communications) could react to anti-violence message in a violent way. There is a tragic paradox: the anti-violence message could increase the predisposition to violent behavior. This would be a case of what some literature called boomerang effect. This article highlights the need for detailed empirical studies on certain effects of media (desensitization, imitation, accessibility and reactance), which could help explain the emergence of the boomerang effect.


Media effects, violence, institutional campaigns, the boomerang effect, desensitization, imitation, accessibility, reactance

PDF file in Spanish

PDF file in English

1. Introduction. Violence as a social problem

Today violent behavior is one of the problems that most concerns society as a whole. Numerous public institutions and diverse social-action organizations (NGOs, Anti-violence associations, etc.) have begun to implement different initiatives to eradicate or at least minimize violent conduct as much as possible.

In this article we concentrate on those initiatives that focus on awareness and sensitization campaigns against violence in order to consider the extent to which these measures are effective and explain why they may be failing. We begin with two proven facts: a) an important communicative effort is being made against violence, but at the same time, b) the data suggest that this effort is not generating the desired results.

The evidence that an important dissemination effort is underway is that the anti-violence awareness campaigns have required a significant economic investment over the last several years. For example, according to the Spanish Ministry of Equality, in 2008 the state-funded campaign against gender violence Ante el maltratador, tolerancia cero cost 4 million euros to fund.

Nevertheless, the desired results have not yet been achieved. Despite the existence of these awareness campaigns, violent behavior has not decreased, with some of the indicators reflecting truly alarming statistics. For example, in the last decade, the total number of violent crimes has experienced a significant increase:

Meanwhile, the statistics of victims of gender violence in Spain during the last decade also show a similar worrying trend despite the fact that now is precisely when more measures are being put into place to eradicate this serious social problem1.

Therefore, the question that needs asking is: What is going wrong? Although it is evident that social phenomenon can result from diverse causes, one of the possible reasons may be the clearly limited effectiveness of the campaigns designed to sensitize the population against the use of violence. This would explain why the statistics on the occurrence of violence remain unchanged, or do not show a significant decrease. How can one explain that the number of violent acts increase after awareness campaigns? In this case, we are not only talking about the ineffectiveness of these campaigns, but also of a much more relevant and problematic issue: the possibility that an unforeseen perverse effect is being generated. Our hypothesis is that although the majority of people take on the anti-violence message as their own, there is a reduced number of individuals with a higher propensity towards violence that may react to these messages in a very undesirable way, in that the campaign’s message may cause a higher predisposition in them for developing violent behavior; resulting in what some literature calls the boomerang effect.

.In this context, critical reflection is needed to determine the social consequences of anti-violence awareness campaigns and identify the causes behind their apparent failure, and at the same time allow us to find the key to developing new campaigns that would be more effective against all types of violence. Several lines of reasoning can aid in explaining the problem. In this article, we will discuss some of them in detail.

2. The root of the problem

When designing an awareness campaign, one of the first steps to follow is to determine to whom the message is directed, who our target audience is. This means that the characteristics of the intended recipient of the campaign may be quite diverse and in the case of sensitization campaigns against violence, it may be especially important to keep in mind that some people are more prone to violent behavior and that their exposure to the campaign could generate different responses in them than those expected.

According to data from a 2008 survey on the use of cellular phones among minors, a sample from the Autonomous Region of Madrid of 1053 minors between 10 and 16 years of age demonstrates that roughly 10% of the child and young adult population are particularly prone to violent behavior (García Galera & al., 2008). The results of this study reveal that these young people confess their desire to record the hooliganism of others, show indifference to or enjoy watching violence posted on the Internet, and even on occasion have used their cellular phones to film fights, humiliating or violent acts (for example, pranks played on professors) or have posted these recordings on the Internet (YouTube, MySpace).

This is clearly alarming data, and presents us with a phenomenon that is quantitatively and qualitatively relevant to social coexistence. We are witnessing a scenario in which certain youths demonstrate an elevated degree of insensitivity and tolerance toward certain acts of violence, which they not only enable, but on occasion sometimes participate in. In our opinion, this data should be considered when designing anti-violence campaigns that aim to sensitize this target audience that unquestionably is the intended recipient of the message.

3. The risk of the boomerang effect in awareness campaigns: Empirical evidence

If, as mentioned above, the main institutional strategy used to combat undesired social behavior consists of the dissemination of awareness campaigns aimed at sensitizing the population with respect to different social and public health problems (abuse of alcohol, tobacco or other drugs), it has been demonstrated that in certain circumstances, these campaigns could be generating an effect contrary to the intended one. In fact, it would appear that it may be precisely the very target audience of these campaigns (alcoholics, smokers or drug-addicts) who are more prone to reject or experience the boomerang effect from the institutional message.

In this respect, in a variety of fields where institutional campaigns are used to warn about the risks of developing certain behaviors, an abundance of empirical evidence is being gathered on the boomerang effect. Of special significance are the following: campaigns that stress the risks of smoking (Hyland & Birrell, 1979; Robinson & Killen, 1997; Unger & al., 1999); campaigns against drug use (Feingold & Knapp, 1997); or those that focus on alcohol consumption (Ringold, 2002).

In the field of violence, there is a limited corpus of investigations, although one could cite studies such as the one by Bushman and Stack (1996) in which they reveal how the use of labels that alert about the broadcasting of programs with violent content could increase the audience’s interest for viewing the programs. If, as it has been demonstrated, a relationship exists between the exposure to violent content and the subsequent impulses and acts of violence, the problem would be that the use of these labels leads to a higher consumption of measured violence, and as a consequence, a higher level of real violence.

4. The risk of the boomerang effect in anti-violence awareness campaigns

4.1. An explanation based on the proven media effects

There is a long tradition of in depth studies done on media effects2. Some of these effects have contrasted empirical evidence, such as the ample consensus in the scientific community on the relationship that exists between the consumption of audiovisual violence and the tendency to develop violent behavior in the child and young adult population3. In fact, a number of studies have achieved significant results when correlating the exposure to violent content in the media (mainly on television and in video games) with the generation of violent thoughts, attitudes, and behavior. These effects have been demonstrated for the short, medium and long term. Relevant conclusions have been made for both men and women, and equally significant results have been obtained in a variety of situations studied in different countries. Among others, we can cite the studies by Huesmann and Moise (1996), Anderson (1997), Anderson and Dill (2000), Anderson and Bushman (2002), Huesmann & al. (2003), Anderson & al. (2003), Gentile & al. (2004), and Huesmann and Taylor (2006).

In order to demonstrate the influence that the consumption of audiovisual violence may have on the generation of violent behavior, different mechanisms are used; among which the desensitization effect and the imitation effect stand out. The former allows us to explain why the anti-violence campaigns are ineffective in reducing the number of violent acts; while the latter could explain not only why the campaigns are not effective, but also why sometimes these campaigns generate an effect contrary to the one desired by increasing the probability that violent acts take place.

4.1.1. Desensitization effect

Although it is true that the exposure to violent content initially produces a rejection response, it is also true that repeated exposure to violence ends up creating a process of decreased response or habituation. When presented with successive violent images, the spectator tends to show progressively smaller psychological and emotional responses. A state of emotional desensitization can be reached in which there are no emotional responses to stimuli that when viewed for the first time caused a strong response. Similarly, a cognitive desensitization is produced when violence is no longer considered as something infrequent or abnormal and begins to be viewed as an inevitable and normal aspect of daily life. Both emotional and cognitive desensitization can influence behavior, resulting in either a decrease in the probability that the desensitized person is critical of violent conduct or an increase in the probability that desensitized people develop aggressive conduct, which in turn may be more intense (Drabman & Thomas, 1974; Drabman & Thomas, 1976; Thomas & al., 1977; Molitor & Hirsch, 1994; Carnagey, Anderson & Bushman, 2006).

The desensitization effect has also been studied in investigations on the effectiveness of warning labels on certain products that may be harmful to a person’s health or security. In these studies, the repeated exposure to warning labels of all types (food, road safety, etc.) is found to be a contributing factor when people stop paying attention to them, even leading them to ignore many of them altogether (Twerski & al., 1976). This is especially true in those cases in which the harmful consequences do not immediately arise after engaging in the risky behavior, leading us to what Breznitz (1984) calls false alarms. An example of this would be the messages warning of the risks associated with smoking: while in the opinion of this author it is evident that drinking bleach has an immediate adverse effect, smoking a cigarette does not appear to have any, which makes the warning labels on cigarette packs less effective.

When applying this reasoning to the question of violence, it may be that some especially violent people feel a type of immunity effect regarding their actions, since the immediate consequences for the aggressor of a violent action (for example the prison sentences associated) are seldom discussed. Violent people who consider violence to be a normal part of daily life (cognitive desensitization) may believe (the same as some smokers) that their violent conduct will not result in any negative consequences for them.

Although the desensitization effect may not necessarily be related to the appearance of a boomerang effect, it is important to highlight that the greater the desensitization the person experiences towards violence, the less efficient the anti-violence awareness campaigns will be. Furthermore, if a person’s level of desensitization impedes them from reacting to real-life violence it is unlikely that the anti-violence messages (that usually deliberately avoid using damaging images) will have any effect on them.

4.1.2. Imitation effect

A social creature by nature, the human being learns to repeat or imitate behavior that is apparently valid or common by observing the other members of its community. Because of this, one of the most characteristic effects associated with the media is known precisely as the imitation effect. In the context of anti-violence awareness campaigns, this effect is produced solely in the case of messages that contain violence: news stories that contain explicit violence or campaigns that use images with violent content.

This imitation effect can be produced through two different mechanisms, both possibly resulting in an undesirable boomerang effect. They can be observed through increased violent conduct immediately following an awareness campaign or media piece containing violence:

a) Instrumental validity: the spectator imitates the behavior they view because they deduce that it is useful, since the person who has carried out the action has obtained something beneficial by behaving a certain way. In particular, in the context of violence, studies exist that demonstrate how children and adolescents not only tend to imitate the behavior of those people they interact with most frequently (family members, parents, etc.) but also media personalities. Along these lines, classic studies not only show that children imitate aggressive conduct exhibited by adult role models (Bandura & al., 1961), but that they also imitate the conduct of fictional characters (Bandura & al., 1963a). This is especially true when the imitated action is seen to have a reward (instrumental learning) or when the role model is admired or identified with. Therefore, one can deduce from this that if the awareness campaigns contain violence, they could generate more violence by imitation. Or in other words, it would be preferable that awareness campaigns and news stories on violence avoid displaying violent content in order to avoid the imitation effect.

b) Social validity: the spectator imitates a conduct that they perceive many people to be carrying out, and therefore, they presume that it must be correct behavior. Numerous studies show how people tend to behave the same way other people do since the fact that other people behave a certain way is interpreted as a validating factor about the appropriateness of the behavior (Gould & Shaffer, 1986; Reingen, 1982). This is a factor to consider when designing anti-violence awareness campaigns. Recent studies have shown that when trying to eradicate an undesirable behavior (for example violent behavior) a message that states that unfortunately many people still behave in a certain way may have the exact opposite effect since may of the campaigns focus the public’s attention (especially those with higher tendency towards the behaviors in question) more on the prevalence of the action, providing it with more visibility, than the undesirability of the action (Cialdini, 2003; Cialdini & al., 2006; Shulz & al., 2007). Along these lines, recent studies (Vives, Torrubiano and Álvarez, 2009) have brought to light that television news reports on gender violence have a negative influence on the number of deaths attributed to male violence.

4.2. Other mechanisms that could explain the boomerang effect

In addition to the aforementioned documented media effects, we deem appropriate the mention of two mechanisms that could explain the emergence of the boomerang effect after the dissemination of anti-violence awareness and sensitization campaigns: enhanced accessibility and psychological reactance.

4.2.1. Enhanced accessibility

As we have already suggested, the use of images with violent content in anti-violence messages could increase the probability that violent behavior is reproduced in the future. We believe that a new alternative explanation is possible, based on the fact that the exposure to these images could cause these violent behaviors to be more accessible to the recipients’ minds. Taking it a step further, accessibility (the ease or speed that a construct or concept comes to mind) could also help to explain the possible perverse effect of anti-violence awareness campaigns even when they do not contain violent content. In line with previous investigations that found that the attempt to eliminate certain thoughts can make them even more accessible (Wegner, 1994), a hypothesis could be made that the mass media’s use of messages that refer to violence (even when the ultimate purpose is to criticize it) can have a negative effect by activating and increasing accessibility to violent thoughts and ideas, especially for those individuals already particularly prone to violence.

4.2.2. Psychological reactance

Psychological reactance has been defined as the state of psychological stimulation that arises when our freedom appears to us to be limited or threatened (Brehm and Brehm, 1981). The most direct consequence of this state is a tendency to resist everything that could be considered as a threat to one’s personal liberty (Brehm, 1966). Therefore, in the same way that we tend to show reactance when, for example, we are told how to think or we are given orders, we tend to experience reactance when certain behaviors are forbidden (Dillard & Shen, 2005; Miller & al., 2006; Miller & al., 2007). This means that those people who behave in a way that is criticized by the authorities reaffirm their actions as being a defense against a threat to their way of life.

This is also the same motive that leads people to more intensely desire information that has been censored (Worchel & Arnold, 1973). The explanation is found in the need that some people feel to engage in risky or taboo behavior, or to violate societal norms. Stewart and Martin (1994) believe that the warning messages about the risks associated with certain behaviors attract the attention of some people, impelling them to behave in the manner that was trying to be prevented. It is like eating the forbidden fruit (Bushman & Stack, 1996).

As a result, many researchers have identified psychological reactance as one of the main factors for explaining the boomerang effect caused by different media campaigns (Bushman & Stack, 1996; Ringold, 2002; Hornik & al., 2008). From our perspective, this could also apply to the anti-violence campaigns that generate a boomerang effect when individuals who are more prone to violence or who routinely use violence in their daily lives come into contact with campaigns that prohibit or criticize violence.

5. Conclusions

The need to consider the effects of desensitization, imitation, accessibility and psychological reactance in the awareness campaigns and information dissemination on violence. In summary, the difficulties of ending violent behavior could be related to the lack of adaptation between the objectives proposed by those responsible for social policy (such as the eradication of all violent conduct) and the communication strategies used (such as the anti-violence awareness and sensitization campaigns in the media).

Our aim here is not to assert that the messages about violence in the media or in certain institutional awareness campaigns are the only causes of violence, but rather to point out that not all of the well-meaning institutional campaigns or anti-violence information reach their goal of preventing violence, and that these initiatives could result in harmful effects (the boomerang effect) just as in other areas (for example, the case of drug consumption).

It is our belief, therefore, that in order to avoid generating any negative effects, the different risks shown in the studies on media effects should be taken into account when designing any anti-violence awareness campaigns or portraying violence in the news.

A two-fold proposal for reaching this goal would necessitate on the one hand that the existing studies on desensitization be consulted. Although at first the existence of information and campaigns may have had a positive effect towards the eradication of violence, the reiteration of those messages may have led to the desensitization of the recipients, thus suggesting the possible ineffectiveness of the messages being disseminated.

On the second hand, it should be kept in mind that an imitation effect is possibly being generated, which is even more worrying. If this is the case, not only do we have useless campaigns, but also the risk that the messages about violence or those containing violence may actually cause violent behavior. The imitation effect has abundant empirical evidence supporting it, and therefore institutional awareness campaigns generally keep it in mind. The information disseminated through the media presents a bigger problem since it does not always comply with these standards (Vives, Torrubiano & Álvarez, 2009).

Finally, the risk that the messages against violence are not fulfilling their objectives could also be related to two especially relevant psychological effects. On one hand, the research on construct accessibility show that any message about violence, even those whose aim is to combat it, can cause the concept of violence to be more present in people’s thoughts. On the other hand, studies on reactance beg us to consider the tendency for certain people to position themselves against any message that may threaten their freedom or self-esteem.

At the same time, it is important to add that in the case of the messages designed to combat violence these effects could intensify in those individuals that are particularly prone to developing violent conduct. This is especially worrying since those who are more prone to developing violent conduct are the target audience for anti-violence messages.

This suggests that inefficient strategies are being implemented, or what is worse, we may be increasing the probability that violent behavior occurs after the dissemination of informative or sensitization messages.

As a result, the theoretical reflection and bibliographical review that we have carried out shows the need for a more exhaustive study to be conducted on phenomenon such as desensitization, imitation, enhanced accessibility, and psychological reactance, in order to create a more efficient design for future anti-violence communication campaigns. Specifically, it is particularly necessary that empirical research be developed that would allow for the experimental verification of the hypothesis proposed in this paper.


1 In 2004 the Ministry of Equality was created (incorporated in October 2010 as Secretary General of the new Ministry of Health, Social Policy and Equality) that has implemented diverse measures of prevention, sensitization and action such as the Ley Integral contra la Violencia de Género (L.O. 1/2004) (Law on Integral Protection Measures against Gender Violence), awareness campaigns, pedagogical activities, and a personal attention telephone line, etc.

2 Due to the abundance of publications on media effects, several texts have tried to systematize published information of the research on the effects. Among the classics, the work by authors McQuail (1991) or Wolf (1994) stands out. At the same time, a background in the research in Spanish is had by consulting the work by Brändle, Martín Cárdaba, and Ruiz San Roman (2009); Igartua & al. (2001); Fernández Villanueva & al. (2008); Cohen (1998); and Barrios (2005).

3 The recent elaboration of a text presented to the Supreme Court in the United States by the American Psychological Association (APA) and the American Academy of Pediatrics (AAP) that warned of the proven relationship that exists between the use of violent video games and the subsequent aggressive conduct displayed by children and adolescents (see American Academy of Pediatrics, 2009) is evidence of the consensus among the scientific community.


American Academy of Pediatrics (2009). Pediatrics. (www.pediatrics.org) (15-12-2010).

Anderson, C.A. & Bushman, B. J. (2002). The Effects of Media Violence on Society. Science, 295; 2.377-2.378.

Anderson, C.A. & Dill, K.E. (2000). Video Games and Aggressive Thoughts, Feelings, and Behavior in the La-boratory and in Life. Journal of Personality and Social Psychology, 78(4; 772-790.

Anderson, C.A. (1997). Effects of Violent Movies and Trait Hostility on Hostile Feelings and Aggressive Thoughts. Aggressive Behavior, 23; 161-178.

Anderson, C.A.; Berkowitz, L. & al. (2003). The Influence of Media Violence on Youth. American Psychological Society, 4(3); 81-110.

Bandura, A., Ross, S. & Ross, S. A. (1963b). Vicarious Reinforcement and Imitative Learning. Journal of Ab-normal and Social Psychology, 67(6); 601-607.

Bandura, A., Ross, S. & Ross, S.A. (1961). Transmission of Aggression through Imitation of Aggressive Models. Journal of Abnormal and Social Psychology, 63(3); 575-582.

Bandura, A.; Ross, S. & Ross, S.A. (1963a). Imitation of Film-mediated Aggressive Models. Journal of Abnormal and Social Psychology, 66(1); 3-11.

Barrios Cachazo, C. (2005). La violencia audiovisual y sus efectos evolutivos: un estudio teórico y empírico.

Brehm, J.W (1966). A Theory of Psychological Reactance. New York: Academic Press.

Brehm, S.S. & Brehm, J.W. (1981). Psychological Reactance: A Theory of Freedom and Control. Academic Press: New York.

Breznitz, S. (1984). Cry Wolf: The Psychology of False Alarms. Hillsdale, NJ: Lawrence Erlbaum & Associates.

Brändle, G.; Martín Cárdaba, M.A. & Ruiz San Román, J.A. (2009). El riesgo de efectos no queridos en cam-pañas de comunicación contra la violencia. Discusión de una hipótesis de trabajo, en Nova, P.; Del Pino, J. (Eds.). Sociedad y tecnología: ¿qué futuro nos espera? Madrid: Asociación Madrileña de Sociología; 191-198.

Bushman, B.J. & Stack, A.D. (1996). Forbidden fruit versus tainted fruit: effects of warnings labels on attraction to television violence. Journal of Experimental Psychology: Applied, 2; 207-226.

Carnagey, N.L.; Anderson, C.A. & Bushman, B.J. (2007). The Effect of Videogame Violence on Psychological Desensitization to Real-life Violence. Journal of Experimental Social Psychology, 43; 489-496.

Cialdini, R.B. (2003). Crafting Normative Messages to Protect the Environment. Current Directions in Psycho-logical Science, 12; 105-109.

Cialdini, R.B.; Demaine, L.J. & al. (2006). Managing Social Norms for Persuasive Impact. Social Influence, 1; 3-15.

Cohen, D. (1998). La violencia en los programas televisivos. Revista Latina de Comunicación Social, 6. (www.ull.es/publicaciones/latina/a/81coh.htm) (12-11-2010).

Comunicar: Revista científica iberoamericana de comunicación y educación, 25.

Drabman, R.S. & Thomas, M.H. (1974). Does Media Violence Increase Children’s Toleration of Real-life Ag-gression? Developmental Psychology, 10(3); 418-421.

Drabman, R.S. & Thomas, M.H. (1976). Does Watching Violence on Television Cause Apathy? Pediatrics, 57(3); 329-331.

Feingold, P.C. & Knapp, M.L. (1977). Antidrug Abuse Commercials. Journal of Communications, 27; 20-28.

Fernández Villanueva, C.; Revilla Castro. J.C. & al. (2008). Los espectadores ante la violencia televisiva: fun-ciones, efectos e interpretaciones situadas. Comunicación y Sociedad, 2; 85-113.

García Galera, M.C. (Dir.) (2008). La telefonía móvil en la infancia y la adolescencia. Informe del Defensor del Menor, Madrid: CAM.

Gentile, D.A.; Lynch, P.J. & al. (2004). The Effects of Violent Videogame Habits on Adolescent Hostility, Ag-gressive Behaviors, and School Performance. Journal of Adolescence, 27; 5-22.

Hornik, R.; Jacobson, L. & al. (2008). Effects of the National Youth Anti-drug Media Campaign on Youths. American Journal of Public Health, 98 (12); 2.229-2.236.

Huesmann, L.R. & Moise, J. (1996). Media Violence: a Demonstrated Public Health Threat to Children. Harward Mental Health Letter, 12 (12); 5-8.

Huesmann, L.R. & Taylor, L.D. (2006). The Role of Media Violence in Violent Behavior. Annual Review of Public Health, 27(1); 393-415.

Huesmann, L.R.; Moise-Titus, J. & al. (2003). Longitudinal Relations between Children’s Exposure to TV Violence and their Aggressive and Violent Behavior in Young Adulthood: 1977-1992. Developmental Psychology, 39; 201-221.

Hyland, M. & Birrell, J. (1979). Government Health Warnings and the Boomerang Effect. Psychological Reports, 44; 643-647.

Igartua, J.J.; Cheng, L. & al. (2001). Hacia la construcción de un índice de violencia desde el análisis agregado de la programación. Zer. Revista de Estudios de Comunicación, 10; 59-79.

McQuail, D. (1991). Introducción a la teoría de la comunicación de masas. Barcelona: Paidós.

Miller, C.H.; Burgoon, M. & al. (2006). Identifying Principal Risk Factors for the Initiation of Adolescent Smoking Behaviors: The Significance of Psychological Reactance. Health Communication, 19; 241-252

Miller, C.H.; Lane, L.T. & al. (2007). Psychological Reactance and Promotional Health Messages: The Effects of Controlling Language, Lexical Concreteness, and the Restoration of Freedom. Human Communication Research, 33; 219-240.

Molitor, F. & Hirsch, K.W. (1994). Children’s Toleration of Real-life Aggression after Exposure to Media Vi-olence: a Replication of the Drabman and Thomas Studies. Child Study Journal, 24 (3); 191-208.

Ringold, D.J. (2002). Boomerang Effect: In Response to Public Health Interventions: Some Unintended Con-sequences in the Alcoholic Beverage Market. Journal of Consumer Policy, 25; 27-63.

Robinson, T.N. & Killen, J.D. (1997). Do Cigarette Warnings Labels Reduce Smoking? Archives of Pediatrics and Adolescent Medicine, 151; 267-272.

Stewart, D.W. & Martin, I.M. (1994). Intended and Unintended Consequences of Warning Messages: A Review and Synthesis of Empirical Research. Journal of Public Policy and Marketing, 13; 1-19.

Thomas, H.M.; Horton, R. & al. (1977). Desensitization to Portrayals of Real-life Aggression as a Function of Exposure to Television Violence. Journal of Personality and Social Psychology, 35(6); 450-458.

Twerski, A.D.; Weinstein, A.S. & al. (1976). The Use and Abuse of Warnings in Products Li-ability: Design Defect Litigation Comes of Age. Cornell Law Review, 61; 495.

Unger, J.B.; Rohrbach, L.A. & al. (1999). Attitudes toward Anti-tobacco Policy among California Youth: Asso-ciations with Smoking Status, Psychological Variables and Advocacy Actions. Health Educations Research Theory and Practice, 14; 751-763.

Vives, C.; Torrubiano, J. & Álvarez, C. (2009). The Effect of Television News Items on Intimate Partner Violence Murders. European Journal of Public Health; 1-5.

Wegner, D.M. (1994). Ironic Processes of Mental Control. Psychological Review, 10; 34-52.

Wolf, M. (1994). Los efectos sociales de los media. Barcelona: Paidós.

Worchel, S. & Arnold, S.E. (1973). The Effects of Censorship and the Attractiveness of the Censor on Attitude Change. Journal of Experimental Social Psychology, 9; 365-377.