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Valente, Thomas W.; Myers, Raquel The Messenger is the Medium: Communication and Diffusion Principles in the Process of Behavior Change Estudios sobre las Culturas Contemporáneas, vol. XVI, núm. 31, 2010, pp. 249-276 Universidad de Colima Colima, México

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The Messenger is the Medium: Communication and Diffusion Principles in the Process of Behavior Change

Thomas W. Valente, Raquel Myers

Abstract The most common approach to communicating health promotion messages has been through a single medium, either radio or television. But, as technology and communication advances, experts agree today that it is important, in order to accelerate behavior change, to use a multimedia approach when communicating health promotion messages. This article discusses how communication, in particular interpersonal communication, can be incorporated into community action and other health promotion efforts. Diffusion of innovation theory provides the foundation for this article and we begin by discussing its principles, followed by an explanation of its use in evaluating mass media campaigns. Throughout, we will highlight the importance and role played by interpersonal communication and social networks.

Key words: Communication & Technology Advances, Interpersonal Communication, Mass Media Campaigns

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Resumen El medio es el mensajero: comunicación y difusión de principios durante el proceso de cambios de comportamientos El enfoque más común para comunicar el mensaje de promoción de la salud ha sido recurrir a un solo medio de información, sea radio o televisión. No obstante, conforme avanza la tecnología y la comunicación, los expertos coinciden, hoy en día, en afirmar que es importante utilizar un enfoque multimedios al transmitir mensajes de promoción de la salud, con el fin de acelerar el cambio en los comportamientos. Este artículo explica cómo es que la comunicación, y en particular la comunicación interpersonal, pueden incorporarse a la acción comunitaria y a los esfuerzos de promoción de la salud. La teoría de la difusión de innovaciones fundamenta este artículo, por lo que empieza por discutir sus principios. Enseguida se presenta una expli- cación de su uso en la evaluación de campañas de comunicación masiva. Se destaca, en todo momento, tanto la importancia como el papel desempeñados por la comunicación interpersonal y las redes sociales.

Palabras clave: Avances en comunicación y tecnología, Comunicación interpersonal, Campañas de comunicación masiva

Thomas W. Valente. USA. PhD from the Annenberg School for Communi- cation, University of Southern California. Areas of interest: social network analysis, health communication, and evaluation of health promotion programs designed to prevent tobacco and substance abuse, unintended fertility, and STD/HIV infections. He is currently a Professor and Director of the Master of Public Health Program in the Department of Preventive Medicine, Keck School of Medicine, University of Southern California; [email protected]

Raquel Myers. USA. PhD from the University of Southern California De- partment of Preventive Medicine. Areas of interest: using the law and policy as a mechanism for limiting and preventing disease, HIV/STD prevention, substance us prevention, immigrant health, and healthcare disparities. She is currently attending law school at the University of Utah S.J. Quinney College of Law; [email protected]

ublic health organizations and agencies throughout the world have been Pinvolved in communicating a variety of health-promoting behaviors, including, but not limited to, immunizations, HIV/AIDS prevention, family planning, improving sanitary conditions, tobacco/substance use prevention, and adoption of healthy lifestyles and eating habits. Implemented in many forms, these health promotion programs have been accompanied by extensive research about their planning and effectiveness. The more com-

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mon approach to communicating the health promotion message has been through one single medium, either radio or television. But, as technology and communication advances, experts today agree that it is important to use a multimedia approach when communicating health promotion messages in order to accelerate behavior change. This article discusses how communication, in particular interpersonal communication, can be incorporated into community action and other health promotion efforts. Diffusion of innovations theory provides the foundation for this article and we begin by discussing its principles, followed by an explanation of its use in evaluating mass media campaigns. Throughout, we will highlight the importance and role played by interpersonal communication and social networks.

Behavior Change and the Diffusion of Innovation Diffusion of innovation theory has become one of the platforms that exa- mines how new ideas and practices spread within and between populations (Rogers, 2003). This theory describes the mechanism in which opinions, new ideas, attitudes, and behaviors spread throughout a community (Katz, Levine, & Hamilton, 1963; Rogers, 2003; Ryan & Gross, 1943; Valente, 1993, 1995; Valente & Rogers, 1995). Defined as “the process by which an innovation is communicated through certain channels over time among the members of a social system” (p. 5; Rogers, 1995), diffusion theory has been applied to the spread of various areas of interest, including family planning methods, HIV/AIDS prevention, medical technology, educatio- nal curricula, computer technology, and several other innovations (Kelly, Murphy, Sikkema, & et al., 1997; Murphy, 2004; Singhal & Rogers, 2003; Svenkerud & Singhal, 1998; Valente & Saba, 2001). Diffusion theory is made up of five major components: 1) people pass through stages in the adoption process; 2) diffusion takes time, often a long time; 3) people can modify the innovation and sometimes discontinue its use; 4) perceived characteristics of the innovation influence adoption; and 5) individual characteristics influence adoption. The first two components, the stages of adoption and the time it takes for diffusion to spread are discussed at length.

Researchers hypothesize five stages in the adoption process: knowledge, persuasion, decision, trial, and adoption (Rogers, 2003). Although at first glance, the diffusion of innovation’s stages of adoption may seem similar

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to Prochaska’s stages of change, the stages of adoption signify a person’s progress toward adopting a healthy behavior, while the stages of change indicate a person’s progress toward quitting a harmful one (Prochaska & DiClemente, 1986). Also, the diffusion stages emphasize the role of information and sources of influence, while the stages of change emphasize cognitive dispositions (see p. 42, Valente, 2002, for a comparison of stage models). People become aware of new behaviors at different times. Because they pass through the stages of adoption at varying rates, there is considerable time between the earliest and latest adopters. For instance, Ryan and Gross showed that in spite of the innovation having been superior to the one it replaced, it took 14 years from the first to the last adopter to adopt the use of hybrid seed corn in two Iowa counties (Ryan & Gross, 1943). With respect to health promotion, Quinn and colleagues showed that in Bolivia, during the course of the three year intervention designed to reduce child mortality and malnutrition, the number of infants breastfed within one hour of birth steadily increased with each passing year from 56% to 74% (Quinn et al., 2005). Authors remark that while adoption of exclusive breastfeeding practices was slow during the early stages of the intervention, there were marked and statistically significant improvements by the time the intervention program was concluded from 54% to 65% (p<.001; Quinn et al., 2005). The spread of new ideas and practices can be graphed as the cumulative percent of adopters which typically follows a growth or S-shaped curve (Fig. 1). Because diffusion frequently occurs through personal networks, and personal networks are shaped by ethnic, socioeconomic (SES) factors, and geography, the diffusion of the innovation has a propensity to be shaped by these factors as well. As a result, there may be different diffusion trajec- tories for different subgroups (e.g., fast diffusion for high SES segments of the population and slow diffusion for low ones). When the diffusion of a new behavior occurs, there are few adopters and the growth in new adopters is slow. Research has found that individuals who adopt an innovation early (“early adopters”) are more often persuaded by mass media and other targeted media that provide information that is relevant to the behavior. It is also believed that these early adopters are occasionally free from social norms that would otherwise inhibit them from adopting a new behavior. Whatever the case may be, because new behaviors are uncertain and risky, early adopters have to perceive some reason or benefit in order to adopt the new behavior.

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Figure 1 Typical knowledge, attitude, and practice diffusion curves used to predict the rate of diffusion and the time lag between awareness and use

The stages of adoption and the time needed for the diffusion of the new behavior to occur are graphed in Figure 1. The figure illustrates projected rates of the spread of awareness (knowledge), positive attitude (attitude), and behavior (practice). Expected levels for each can be determined by looking at any point in time. The expected lag between knowledge and practice can be attained by reading across the graph (a straight line from any point on the y-axis). This general model, where awareness (K) eventually leads to a positive attitude (A), which in turn leads to use of the behavior (P), is known as the learning hierarchy. Even though this K-A-P sequence occurs often, other researchers argue that different sequences are possible (Chaffee & Roser, 1986; Valente, Paredes, & Poppe, 1998). For example, some behaviors may be adopted before knowledge of or positive attitudes toward that behavior are developed. For instance, people may use con- doms because they want to protect themselves from pregnancy or sexually transmitted diseases (practice) even though they may not like to use them (low positive attitude), and with little knowledge about their effectiveness (knowledge), thus resulting in the behavioral change sequence to P-A-K. Health promotion and communication campaigns have tried to accelerate behavior change by changing knowledge, attitudes, and directly encouraging people to adopt healthy behaviors, irrespective of the behavior change sequence. Media campaigns serve two specific functions: (1) to spread knowledge rapidly throughout a population so that the knowledge curve grows quickly, and (2) to shorten the K-A-P gap, the time between awareness and use. There has been some discussion over when media

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campaigns are most effective. Some people believe that media campaigns are more effective early in the diffusion process because of the relatively low number of adopters. It is these early adopters to whom later adopters seek out in order to obtain additional information, stimulating interpersonal communication among the population. On the other hand, media campaigns conducted later on in the diffusion process may function as a way to refocus the public agenda back on the behavior (McCombs & Shaw, 1972; Singhal & Rogers, 2003) and to generate greater interpersonal communication (Wolitski, Bensley, Corby, & et al., 1996) needed to sustain behavior change. Mass Media Campaigns Studies on the effects of early communication campaigns have resulted in both successes (Cartwright, 1949; Mendolsohn, 1973; Rogers & Storey, 1987) and failures (Hyman & Sheatsley, 1947; National Public Radio Public Service Announcements, 1996; Udry, Clark, Chase, & Levy, 1972). Many of these studies were conducted by Lazarsfeld and colleagues (Berelson, Lazarsfeld, & McPhee, 1954; Eulau, 1980; Katz & Lazarsfeld, 1955; La- zarsfeld, Berelson, & Gaudet, 1948; Merton, 1949). The cumulative experience from these early studies has highlighted a theoretical outcome: the classic 2-step flow model (Gitlin, 1978; Katz, 1957, 1987). The 2-step flow model hypothesizes that opinion leaders (individuals whom others seek out for their advice or information) use mass media for information more often than opinion followers. These opinion leaders pass on their opinions to the opinion followers. Since the mid-1950s, no other theory has integrated mass and interpersonal communication processes within the context of campaign effects, resulting in a balkanized communication field today (Barnett & Danowski, 1992; Chaffee, 1982; Hawkins, Wiemann, & Pingree, 1988; Reardon & Rogers, 1988; Rice, Borgman, & Reeves, 1988). Scholars have argued that mass media are effective at disseminating information but that interpersonal communication is necessary for behavior changes to occur (Chaffee, 1982; Hawkins et al., 1988; Hornik, 1989a, 1989b; Kegeles, Hays, & Coates, 1996; Kelly et al., 1997; Reardon & Rogers, 1988; Rice et al., 1988; Valente, Poppe, & Merritt, 1996; Valente & Saba, 2001). This knowledge has directed several projects to use mass media to advertise new ideas and products, while relying on outreach, promotoras, and peer education programs to promote adoption (Arenas- Monreal, Paulo-Maya, & Lopez-Gonzalez, 1999; Kegeles et al., 1996; Kelly et al., 1997; Medley, et al., 2009; Venguer et al., 2007).

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One such study focused on reducing child mortality and malnutrition by promoting breastfeeding in Bolivia, Ghana, and Madagascar. This study used mass media, in particular radio, as one important component of the behavior change communication strategy (Quinn et al., 2005). Another major component was incorporating interpersonal communication strategies intended for mothers of infants and also extended family members. The rationale for the approach was the importance of educating and engaging the social networks of mothers (Quinn et al., 2005). Few studies, however, have examined the relative influences of mass and interpersonal communication within a specific study (Hornik, 1989a, 1989b; Valente et al., 1996). As a result, there are few models that inte- grate mass media and interpersonal communication influences. This lack of integration helps continue an under-appreciation of the role of mass media in creating sustainable behavior change. It has also contributes to an under-appreciation of the link between mass media and interpersonal communication. Interpersonal Communication and Social Networks Media campaigns are often thought of as broadcasts to a population of individuals. Yet, the audience is a network of human relationships, con- nected to one another in complex and nonrandom ways. As a result, mass media campaign messages are not received in a vacuum; instead, they are filtered through social networks. People often receive messages with others, and this may directly influence how the message is interpreted and reinterpreted. In addition, people usually converse with others about the health promotion messages, thereby influencing the way the messages are interpreted. Consistently, the topics of media campaigns are designed with the goal of generating interpersonal discussion. Such was the case in a national family planning campaign conducted in Bolivia (Valente & Saba, 2001). The mass media campaigns focused on radio, print, and television spots. The interpersonal communications that arose as a result of the campaign was found to be strongly and positively associated with behavior change (Valente & Saba, 2001). The first attempt to create a model linking mass and interpersonal communication was the 2-step flow hypothesis by Katz and Lazarsfeld (Katz, 1987; Katz & Lazarsfeld, 1955). The 2-step flow hypothesis proposed that the media communication influences opinion leaders. Opinion leaders were found to be more aware of current events and were more likely to

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receive more information from the media than non-leaders. Opinion leaders influence others who are less attentive to those media communications. In order to convince others to follow their opinions, opinion leaders used media communications to support their arguments. These opinion leaders “make extensive use of the media to stay expert on their favorite subjects and become trusted sources of information for others” (Gladwell, 2003). Figure 2 shows a simplified model of mass media influencing opinion leaders, who in turn influence others. Usually, these others are thought to be family, friends, coworkers, and perhaps acquaintances –generally people with whom they are close to and have strong credibility and trust with. This model, however, may be an oversimplification. It may be that the media communications influence opinion leaders, who then influence others, and these other then influence more others– a 3-step or even multi-step flow. Figure 2 Mass media influence opinion leaders who in turn influence others

Furthermore, it may be that some opinion leaders influence only one or a few others, whereas other opinion leaders may have much higher multiplier effects, influencing five, ten, or hundreds of others. Figure 3 attempts to capture this complexity. These models, however, do not take into consideration a number of other factors regarding the media influence process. First, it is likely that opinion leaders are influenced by others just as much as others are influenced by them and that media shape their messages in accordance with what they think the audience wants to see or hear. Essentially, to state that media communications influence A, whom influence B, may be an oversimplification. Second, individuals are embedded within complex social network

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Figure 3 Mass media may influence opinion leaders who then influence a different number of other individuals

structures. Some people have small networks, whereas others have quite large ones. Some social networks are integrated (their friends know each other) whereas others are radial (their friends do not know one another). What follows are three ways in which social network structures can affect media processes. First, Potterat and colleagues suggest that the structure of the network, especially the cohesiveness of an individual’s network, is associated with greater sexually transmitted disease and HIV risk for the individual (Pot- terat, Rothenberg, & Muth, 1999; Rothenberg et al., 1998). The authors report that lower cohesiveness of network members is associated with lower STD/HIV transmission, even in a high-risk population. Second, the norms held within social networks alter the media influence process. For example, if a social network comprised of young adults has negative safer sex norms, a media campaign designed to target and change these norms may increase condom use. Third, the degree of similarity or difference between a person and his or her social contacts (homophily) also affects the flow of ideas and behaviors. It is believed that information flows and persuasion occurs more readily among homophilous dyads, that is, people

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who are like one another, rather than among non-homophilous dyads (Ro- gers, 2003). Consequently, diffusion, as mentioned earlier, tends to occur along sociodemographic lines because social networks are contoured by sociodemographic characteristics. Finally, there is great variation in risk taking and risk avoidance within a population. This also may affect the media influence process. It is well known that there is considerable variation in the amount of influence required for a person to adopt a behavior. Some people will adopt new behaviors only when a minority of their friends or the population has done so. Others wait until a practice is widely accepted before they are willing to adopt it (Valente, 1995). The above factors indicate that the relationship between mass media and interpersonal communication is multifaceted. Unlike the simple opinion leader models presented earlier, it is more likely that people pay attention to media communication, and then they interpret and discuss it in unanticipated ways. One such unanticipated way results in a boomerang effect. For example, an anti-tobacco campaign may be parodied by the intended audience, resulting in boomerang (opposite) effects rather than anti-tobacco effects (Sebrie & Glantz, 2007). Given this reality, researchers would benefit from the inclusion of varia- bles that measure program exposure. Such questions can focus on whom the respondent watched the media or program with, or with whom they participated in the activities with. Researchers should also ask the respondent whether the other individuals in attendance approved of the message or activities, and, most importantly, whether they discussed the messages or activities. Finally, if the message was discussed, it is important to ask what they said to each other. Obtaining information about who they discussed the messages with and what was said may provide valuable information for understanding program effects and designing future activities.

Selecting a Communication Channel One of the items that can have a profound influence on the effectiveness of behavior change programs is selecting the appropriate channel or medium. At times, people attend to and prefer impersonal media, whereas at other times, they prefer personal media. The extent to which behavior change programs incorporate personal and impersonal media may directly correlate with program effectiveness. Keeping in mind the interplay between mass and interpersonal communication during the behavior change process, we now consider the channels used to disseminate information or to persuade

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individuals to engage in healthy behaviors. Table I describes six ecologic levels that provide the context and refe- rence for health promotion interventions. At each level, different types of promotions, each with distinct advantages and disadvantages, can be made. One such intervention can be conducted at the individual level. This level Table I. Ecologic Levels of Analysis and Intervention: Advantages and Disadvantages

Ecologic Level Advantages Disadvantages

Can be tailored; are direct Effectiveness Individual and immediate; dependent on similarity/ treatment some attempt to use empathy between site one-on-one “brief interventions” patient and provider

Effectiveness depends Working in bounded, Organizational on organizational closed communities; worksite, factors; variability more control over the school, etc. between organizations intervention and setting of the same type

Take a long time to Generally most effective; forge collaboration Community-based empowering and sensitive and work with groups; approaches to community dynamics hard to scale up and replicate

Reach many people; can Usually do not change Mass media TV, change societal/ normative a large percentage; radio, and print perceptions; can change dependant on quality; some people’s behavior specific to the situation

Somewhat Can target few people; Policy local and unpredictable; small changes can have global levels replication would be big effects; highly visible uncertain

Multipronged address supply Addresses both Can be expensive; hard and demand for motivations and to coordinate media health-related barriers of change and messages behavior

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can be aimed at clinics and treatment sites where receptionists and providers can be trained to deliver health promotion materials. Individuals visiting these sites can receive a variety of materials designed to inform and help them make healthier behavioral choices. A limitation to individual-level interventions is the fact that many people in need of health promotion and treatments do not visit clinics or other treatment centers. Interventions conducted at the individual level have been quite popular throughout Latin America, in particular among rural villages and poor neighborhoods (Inchaurraga, 2003; Rogow, 2000; Venguer et al., 2007). In Argentina, in spite of there being no needle exchange program, pharmacists are encouraged to sell syringes to drug users and to recommend bleach to clean injecting equipment (Rossi, Touze, & Weissenbacher, 1999). In other instances, individual level interventions are sometimes accompanied by mass media, using promotoras and peer educators as key elements in conveying information throughout the community on a predominantly one-to-one, door-to-door basis (Murphy, 2004; Quinn et al., 2005; Ramos, Green, & Shulman, 2009; Venguer et al., 2007). Interventions can be conducted on an organizational level as well. The- se interventions are designed to reach people in their schools, worksites, and in the community organizations to which they belong. Organizational interventions have the advantage of reaching people in places where they naturally assemble. It also provides a captive audience for health promotion programs. More often than not, organizations are willing and able partners to such efforts. In fact, community-level programs explicitly partner with community groups to create culturally sensitive and culturally tailored programs designed to reach people “where they live, work, and play.” Such interventions are based on principles of empowerment and community effi- cacy (Glanz, Rimer, & Lewis, 2003). One study conducted its intervention among elementary school students in two Mexican states (Pick et al., 2007). The intervention focused on life skills training, in particular improving communication skills, with the goal of ultimately preventing HIV/AIDS (Pick et al., 2007). Another study conducted in Guatemala reported that participation in a local community group was an important conduit for improved hygienic beliefs with regards to curtailing the spread of diarr- heal diseases among their children (Goldman, Pebley, & Beckett, 2001). Increasingly, churches and other faith-based organizations are becoming sites for health promotion (Lopez, Castro, Lopez, & Castro, 2006). Chur- ches have strong bonds with their communities and represent credible and trusted sources of strength and support. A number of programs have used churches for health promotion activities with considerable success (Fox,

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Stein, Gonzalez, Farrenkopf, & Dellinger, 1998; Lopez et al., 2006). Community level interventions work in a similar fashion as organizational- level interventions as they both operate in closed communities. Community based approaches, however, may be more effective because they are more sensitive to community dynamics and norms, and they tend to reach a greater number of the community members. These types of interventions may also incorporate other ecological levels, such as individual, organizational and mass media in order to provide a well-rounded approach to the intervention (Arenas-Monreal et al., 1999; Quinn et al., 2005; Venguer et al., 2007). Often, “buy-in” from the local government and/or local leaders is necessary (Murphy, 2004; Venguer et al., 2007). Mass media interventions can be cost-effective ways to reach a large number of the population with important information. Common types of information conveyed in such a manner include the availability of treatment services, information hotlines (800 numbers) and web sites. Scholars have found two critical elements influencing program effectiveness of mass media interventions. First, the communication should be entertaining. Entertainment appeals to an audience and captures their attention. By entertaining the audience, health promotions can reach people who normally would not attend to health messages and who would normally not be inclined to listen to promotions. Because exposure is a requirement for communication effects regardless of the medium, incorporating entertaining communications will usually increase the number of people who receive the message. Second, the communication should personalize the message. Because interpersonal communication is often a requirement for behavior change, using personal models and testimonials with whom the audience can identify helps increase the effectiveness of the communications. These methods also serve to stimulate interpersonal communication among individuals. Communications, whether personal or impersonal, should be personalized. Finally, at the highest ecologic level is the creation of policy changes that facilitate behavior change. Although often not thought of as a communication strategy, policy change is often a communication strategy in the following ways. First, lobbying and advocating for policies requires interpersonal communication with lawmakers and policymakers. Second, mass media campaigns are often used to mobilize public opinion to generate pressure for policy changes. Finally, policy changes are often accompanied by media campaigns promoting the change so that the recipients of the

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new policy can benefit. For example, in 1995, the Mexican government established policy objectives for the year 2000 to reduce fertility rates, reduce the annual population growth rate, and to increase the use of con- traceptives nation-wide (Seltzer, 2002). Other Latin American countries have implemented similar policy objectives. Policy changes on a national basis often results in the government itself providing support for these family planning programs, conducting the interventions via their respective ministries of health or some other governmental institution such as the national social security program (e.g. Peru and Mexico; Seltzer, 2002). As a result of these family planning policy changes throughout the region, 15 of 18 Latin American countries (all except for Bolivia, Guatemala, and Haiti) have achieved contraceptive prevalences of 50% or more (p. 25; Seltzer, 2002). Others have built consensus through policy advocacy (Quinn et al., 2005). Not all changes in policy lead to desired results. Argentina has a “zero tolerance” approach when it comes to drug users (Inchaurraga, 2003). Re- lated policies have essentially excluded drug users, including intravenous drug users, from accessing the health care system altogether. Having one of the highest incidence rates of HIV among the Latin American countries, such policies may exacerbate the spread of HIV. Even though Argentina maintains a “zero tolerance” policy, a recent law was passed that “endorses interventions aimed at reducing risks among the population of injection drug users not in treatment” (p. 369; Inchaurraga, 2003). In summary, there are different channels available at different ecologic levels to strategically plan communication for healthy behaviors. Selecting a particular strategy should be guided not only by practicality, but also by the method that allows for the opportunity to combine impersonal and personal communications in appealing and entertaining ways. In so doing, the audience may be more likely to pay attention to the message and subse- quently internalize it. These two factors (entertaining and personalization) increase the likelihood that the messages will be discussed within personal networks, thus facilitating behavior change.

Segmentation and Social Networks

Marketing communication incorporates several characteristics, one of which is audience segmentation. Segmentation divides audiences into distinct groups in order to specifically tailor messages for each group.

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Segmentation occurs in many forms: 1) geographic segmentation targets messages based on region (using different indigenous dialects depending on the region of the country); 2) sociodemographic segmentation occurs when messages are tailored on gender, age, ethnicity, or socioeconomic status; and 3) psychographic segmentation uses psychographic profiles that classify individuals on dimensions such as individualism, adventurousness, risk taking, and so on. We suggest a fourth type of segmentation: sociometric. Sociometric segmentation occurs when messages are targeted to individuals based on their social network position. For example, messages aimed at opinion leaders, particularly those identified through social network analysis techniques, would be an example of sociometric segmentation. Another example of sociometric segmentation would be to create messages aimed at core groups within networks. For example, in an attempt to contain the spread of HIV/AIDS throughout a community, it is important to identify core transmitters, in other words, individuals who have a large number of sexual contacts. Should one of these core individuals become infected with HIV, they have the potential to infect large numbers of individuals, accelerating the spread of HIV because of their high sexual activity (Klovdahl, 2001; Potterat et al., 1999).

Another form of sociometric segmentation is directing health promotion messages toward social isolates. In contrast to targeting opinion leaders, interventions could design their messages for social network isolates, individuals with few or no social contacts. Messages that appeal to isolates would likely be different than those that appeal to leaders.

Audiences could also be segmented based on whether a person has many friends who engage and/or support a particular behavior versus those who have few. For example, it may be that the majority of community members support anti-tobacco messages in order to prevent tobacco-related diseases, but there are some individuals who resist. Messages targeted to these individuals would stress that many others have already quit smoking, and there are many social supports available to them if they desire. On the other hand, if people who have few personal contacts are identified because they have tried the innovation, the resulting message might stress that the potential adopter will be “on the cutting edge” or a “leader of the pack” by adopting the new behavior. This type of segmentation would be based on personal network exposure to the behavior.

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Social network analysts have devised a number of ways to identify positions within a network, often decomposing networks into groups and positions. Any of these procedures could be used to develop health promotion interventions. In fact, one researcher suggests that behavioral change may be easier to maintain if interventions are created and implemented based on structural characteristics of the network (Aral, 1999). For example, software could be created in which users enter the names of their friends and their friends’ risk behaviors. The information could then be visually reported back to the user with an estimate of his or her risk status based on their personal network’s risk behavior. Social network segmentation would also lead to designing interventions that specifically focus on creating communications that generate greater interpersonal communication within networks and provide people with the tools needed to have these conversations. For example, entertainment education strategies (Singhal & Rogers, 1999) may be effective at creating behavior change because it generates interpersonal discussion about the topic among the viewers.

Social Networks as a Vehicle for Message Delivery Peer influence and peer modeling are significant correlates of behavior and behavior change (Alexander, Piazza, Mekos, & Valente, 2001; Valente, Watkins, Jato, & et al., 1997). Therefore, harnessing the power of peer influence for health promotion is logical. This power is most likely to be harnessed by allowing peers to deliver the health messages. Although peer leaders are defined in different ways (see Kelly, St. Lawrence, Stevenson, & et al., 2004, for a description of a popular opinion leader model), peers have been used in many settings with generally favorable results (Althabe et al., 2008; Althabe et al., 2005; Kelly et al., 2004; Singhal & Rogers, 2003; Valente & Davis, 1999; Valente et al., 1997; Valente, 2010). In at- tempting to improve obstetrical care in Uruguay and Argentina, one study used peer leaders in an intervention designed to lower routine use of epi- siotomies and increase the active management of the third stage of labor in order to prevent postpartum hemorrhage (Althabe et al., 2008). Study results indicate peer leaders were effective in improving birth outcomes (Althabe et al., 2008).

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Figure 4 (A) Social network of physiciansin one community in Illinois in the mid-1950s from Coleman and others (1966) 07/06/2010 01:14:05p.m. 10 EnsayoValentepp249-276.indd266

Figure 4 (B) Network partitioned into groups 07/06/2010 01:14:06p.m. and leaders chosen as those who received the most nominations within the group 10 EnsayoValentepp249-276.indd267

Figure 4 (C) Optimal assignments based on leaders being assigned to those who nominated them or are “closest to” in the network C 07/06/2010 01:14:06p.m. Thomas W. Valente, Raquel Myers

There are two recently proposed approaches to improving peer delivery of health messages in ways that capitalize on the local nature of opinion leadership. The group model involves identifying groups within social networks first (these can include subgroups and cliques), and then identifying peer opinion leaders within each of those group. This model was proposed and pilot-tested in a school-based tobacco prevention program (Wiist & Snider, 1991) and was further developed and implemented in a worksite nutrition promotion program (Buller, Buller, Larkey, & et al., 2000; Bu- ller, Morrill, Taren, & et al., 1991). This model begins with identifying subgroups or cliques within a network and then selecting peer opinion leaders from each clique. The peer opinion leaders are identified as those people who received the most nominations in response to the question: “Whom do you go to for advice?” A graphic representation of this model is depicted in Figure 4. Figure 4A displays a social network of advice gi- ving among 45 medical doctors in one Illinois community (data are from Coleman, Katz, & Menzel, 1966). Figure 4B shows the same network with groups defined and leaders identified within each group.

Another method of improving peer delivery of health messages is the network leader model. This model begins with identifying peer opinion leaders first and then grouping network members to each leader, thereby creating new cliques. This model was proposed by Valente & Davis.(1999) and tested in a school-based smoking prevention program (Valente, Hoff- man, Ritt-Olson, & et al., 2003). Opinion leaders were defined as those members of a network who receive the most nominations as people others go to for advice. Once the leaders are identified, other network members are matched to each leader based on their “closeness” in the social network. Figure 4C rearranges the network so that the leaders are selected and members assigned to the leaders they nominated or are next closest to. Table II reports the identification (ID) numbers of leaders and their social network members for the two different models described. The two approaches yield different leaders (two of the three leaders differ) and different network members. Although the conceptual approaches of the two models are similar, the resulting leader and network members are quite different. It also warrants noting that a number of assumptions are built into the reali- zation of both methods. For the group model, there are numerous ways to identify subgroups/cliques depending on whether the individual subgroups/ cliques need to be the same size and whether the subgroups/cliques need to be mutually exclusive. For the networked leader model, leaders were chosen based only on a count of the number of nominations they received,

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not whether they were received by the same or different people (Borgatti, 2006); either method can capitalize on the order of nominations made, adding more weight to the first nomination, for example, and both need to make assumptions about how to assign isolates.

Table II. Comparison of Leader and Group Member Assignments for Group and Networked Methods of Network Partition

Method Leaders Group Members

1 4 6 10 13 14 18 20 21 22 32 33 41 42 43 44 Opinion leader 24 2 5 7 8 9 12 15 23 25 27 30 37 39 51 grouped 31 3 11 16 19 26 28 29 38 40 53 56 57 58

8 1 2 3 4 5 13 14 15 16 18 19 28 31 32 57 Opinion leader 23 10 12 20 21 22 25 26 27 29 33 37 38 39 58 networked 24 6 7 9 11 30 40 41 42 43 44 51 53 56

Studies using social networks as delivery vehicles have reported considerable success (Amirkhanian, Kelly, Kabakchieva, McAuliffe, & Vassile- va, 2003; Valente & Davis, 1999; Valente et al., 2003). The approach is both intuitively appealing and is supported by behavior change theories that stress the importance of opinion leadership, homophily, and group dynamics. The main limitation to these approaches is that they are used primarily in closed settings, such as schools, workplaces, organizations as these approaches may not be feasible in large community and population settings. In a city of tens of thousands, it is not feasible to identify leaders and assign them to those who nominated them or to identify networks/ cliques based on social network ties.

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Conclusion This article used diffusion of innovation theory to explore the implications for behavior change programs. Following an introduction of the principles of diffusion of innovation theory, we discussed the history of media campaigns and other methods of communication. Throughout, we stressed the importance of incorporating interpersonal communication into health promotion interventions in order to obtain enhanced campaign effects. Early models of the association between interpersonal communication and mass media were introduced, including a review of the 2-step and multi-flow hypothesis. The 2-step flow hypothesis proposed that media influence opinion leaders; these opinion leaders then, in turn, influence their less attentive peers. Support for the 2-step flow hypothesis has yet to be provided, mostly because individuals inhabit multiple and complex social networks. Given the complexity of interpersonal dynamics and behavior change processes, we discussed a few ways in which interventions can be developed within the context of ecologic levels of influence. Even though different types of interventions are needed based on the ecologic level, and many health promotion interventions conducted throughout Latin America incorporate more than one level at a time, it should be stressed that principles of entertainment and interpersonal communication can, and should, remain a focus. We then discussed sociometric segmentation as an extension of geographic, sociodemographic, and psychographic segmenting. Sociometric segmentation recommends the identification of audiences based on their position within a social network, whether an opinion leader, isolate, or bridge (an individual who connect two or more networks). In addition, it can be used to tailor messages to those with many adopters in their network or those with few. Again, we stress that interventions could also be used to generate interpersonal communication within these social networks. One of the results of using social networks is to use them as delivery vehicles. The messenger is as important as the message. Therefore, methods are being developed that use naturally occurring social network structures to deliver health promotion programming. Two similar models were re- viewed: a group model and a networked leader model. In the group model, subgroups (or cliques as they are sometimes referred to) within a network are identified. Leaders are then chosen from within each subgroup. On the other hand, in the networked leader model, opinion leaders are identified and then social network members are assigned to leaders based on who he/

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she chose as a leader or who he/she is “nearest” to in the network. Although the incorporation of either of these two methods has yet to be conducted in Latin America, data from a classic diffusion study was used to illustrate. We began with an early conceptualization of how mediated communications can be used to change behavior. We then focused on interpersonal communication and how its incorporation may lead to greater dissemi- nation of health promotion messages. This naturally led to considering behavior change processes within social networks. We proposed that social networks be used as delivery vehicles as these channels are often ignored in our attempts to spread health promotion messages to a large audience. Understanding that who delivers the message and in what interpersonal context may be just as, if not more important, than the message itself. Even though the use of promotoras and other peer leaders is common throughout Latin America, using social network analyses may result in better, more relevant, and perhaps more effective health promotion programs. All mass media are personal media and are used in interpersonal ways. Future studies should incorporate aspects we have proposed in this paper, such as network structure, opinion leaders and social networks in order to enhance health promotion in Latin America. Future studies should also evaluate the benefit of network information in determining who should deliver the messages and in what interpersonal and group settings. Finally, future studies would benefit from measuring interpersonal communication about prevention messages in order to determine how people receive the messages and how their social networks moderate or mediate program effectiveness.

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