Mark A. Hamilton

A Meta-Analysis of the Effect of Mediated Health Communication Campaigns on Behavior Change in the United States

A meta-analysis was performed of studies of mediated health campaigns in the United States in order to examine the effects of the campaigns on behavior change. Mediated health campaigns have small measurable effects in the short-term. Campaign effect sizes varied by the type of behavior: r¯ = .15 for seat belt use, r¯ = .13 for oral health, r¯ = .09 for alcohol use reduction, r¯ = .05 for heart disease prevention, r¯ = .05 for smoking, r¯ = .04 for mammography and cervical cancer screening, and r¯ = .04 for sexual behaviors. Campaigns with an enforcement component were more effective than those without. To predict campaign effect sizes for topics other than those listed above, researchers can take into account whether the behavior in a cessation campaign was addictive, and whether the campaign promoted the commencement of a new behavior, versus cessation of an old behavior, or prevention of a new undesirable behavior. Given the small campaign effect sizes, campaign planners should set modest goals for future campaigns. The results can also be useful to evaluators as a benchmark for campaign effects and to help estimate necessary sample size

An Empirical Test of an Axiomatic Model of the Relationship Between Language Intensity and Persuasion

The study tested six axioms concerning the effect of language intensity on receiver attitudes. The axioms specify source and receiver variables which might moderate the relationship between intensity and attitude change. The results were consistent with an information processing model based on message discrepancy, expectancy and elaboration likelihood theories. Intensity affected attitudes through three routes. First, intensity increased attitude change via message clarity, with clarity acting as a mediator variable. Second, intensity inter acted with discrepancy and perceived source likeability to produce attitude change. Third, the effect of intensity on attitudes was moderated by source expectations. Results showed that intensity enhances persuasiveness for a high credibility source, inhibits persuasiveness for a low credibility source, and has no effect for a moderate credibility source. Receiver anxiety moderated the effect of source gender expectations on the intensity-attitude relationship. A revised model of intensity effects, based on axioms derived from information processing theory and expectancy theory, is discussed.

Message Variables That Mediate and Moderate the Effect of Equivocal Language on Source Credibility

Equivocation is advisable as a persuasive strategy only under limited conditions. Information-processing theory was used to model the effect of precise language on receiver evaluations of message and source. Path analyses found that the effects of language intensity (specificity and opinionatedness) on ratings of source competence and trust-worthiness were mediated by language perceptions and message evaluation variables such as assessed argument quality. The effect of language intensity on trustworthiness was mediated by attributions of either source bias or intolerance of discrepant opinions. Meta-analyses found that message discrepancy and personalization of the issue made the effects of intense language on competence more negative, whereas better quality arguments made the effect of intensity on competence and trustworthiness more positive.

Extending an information processing model of language intensity effects

The information processing model of persuasion was used as the basis for a mathematical model of language intensity effects. The model proposes that attitude change is a product of message discrepancy, source evaluation, and message strength. The results show strong support for the model. The salient source evaluation dimension was perceived trustworthiness. Language intensity enhanced attitude change directly, by acting as a multiplier of message strength, and indirectly, by increasing message discrepancy. These effects held for female as well as male sources. Path analysis indicated the presence of source evaluation heuristics. Intensity enhanced source ratings through a positively linked causal chain from intensity to dynamism to expertise to trustworthiness. Intensity also had negative effects on post‐message expertise and trustworthiness unmediated by dynamism.

The design and analysis of language experiments in communication

The traditional design for the study of language variables is a controlled message design in which one kernel message is manipulated to produce message variations that represent the language variable contrasts. Thus message content is the same across treatment conditions and hence crossed with the treatment factors. Jackson and Jacobs (1983) criticized this design on three grounds. They argued that messages should be natural rather than contrived, that messages should be nested within treatment conditions rather than crossed with treatment factors, and that each study should use as many messages as possible. Their paper has been used by reviewers as the basis for rejecting studies done using the traditional design. This paper presents a detailed analysis of the arguments presented in Jackson and Jacobs (1983) as well as subsequent papers by Jackson (1984) and Jackson and Jacobs (1987). The arguments are shown to contain both methodological and substantive errors. When the arguments are corrected, it is sh...

The Effect of Image Features on Judgments of Homophily, Credibility, and Intention to Use as Avatars in Future Interactions

Avatar characteristics influence the perception of the people they represent in a process that is remarkably similar to the way physical bodies influence person perception offline. This is consistent with the Social Responses to Computer Technologies model, which argues that people respond similarly to computers and people as long as sources are perceived to be intelligent. Similarly, Information Processing Theory suggests that the viewers apply the same evaluation sequences to nearly all sources and that more processing resources are allocated to perceiving an entity with social potential. To address the extent to which static avatars are perceived to be intelligent and human like, or have social potential, participants (N = 261) each evaluated a random set of 10 images as potential avatars. The avatars varied with respect to level of computer manipulation, visible indicators of masculinity, and anthropomorphism (having human characteristics). Results confirm that even static avatars are anthropomorphized and that visual characteristics influence perceptions of the avatars. Level of computer manipulation, masculinity, and anthropomorphism all influence perceived levels of realism, competence, and the sense of homophily with the avatar. The implications of these results for theory, future research, and for users and designers of communication systems are discussed.

Testing Hierarchical Models of Argumentativeness and Verbal Aggressiveness

Support was found for a hierarchical model of argumentativeness theory (N = 1541) in which the second-order factors of motivation to argue and verbal aggressiveness exert top-down influence on subsidiary motives and attitudes. Emotional involvement with arguing and emotional involvement with verbal aggressing were added to clarify the originating theory and to improve model fit. The argumentativeness scale was heterogeneous, consisting of distinct ability and motivation to argue factors. Ability to argue had a direct negative effect and an indirect positive effect on verbal aggressiveness, with this positive effect mediated by motivation to argue. The positive effect of motivation to argue on verbal aggressiveness was moderated by college education, suggesting that students acquire a debate schema during their first semesters of college that enables them to better control their arguments, preventing escalation into verbal aggression. The methodological and theoretical implications of the results are discussed.

Relational Dynamics and the Expression of Aggression and Comforting Between Siblings

A study of siblings tested a relational dynamics model set in the family and based largely on Belief Systems Theory. Participants (N = 351) in a 3 (biological relatedness) × 2 (participant sex) × 2 (other sibling sex) quasi-experimental design evaluated their relationship with their sibling. Path analysis was used to track the effects of the independent variables on verbal aggression and verbal comforting. Mediating variables completed two distinct processes. The egocentric assertion of power and hostility between siblings mediated a sequence related to selfish emotions within the individualistic affect system. This sequence is anchored in parent–child verbal aggression and culminates in sibling verbal aggression. Empathy and strength of sibling bond mediated a sequence related to prosocial emotions within the cooperative affect system. This process is anchored in parent–child closeness and ends with expressions of comfort between siblings. The results provide an explanation for the emotional ambivalence of sibling relationships.

Does Evaluation Design Impact Communication Campaign Effect Size? A Meta-Analysis

To examine how methodological choices and artifacts of evaluations influence the estimated effect size of media campaigns on health behavior, we meta-analyzed 44 mediated health campaigns. Effect sizes were largest when the posttest evaluation occurred close to the end of the campaign and utilized a one-group partition-by-exposure design. Use of a self-selected sample and greater sample attrition biased the results by inflating effect sizes. Improvements in the control community over time made it more difficult to detect intervention effect sizes. Design factors that did not result in different effect sizes included panel versus cross-sectional, behavioral versus physiological measure, and nonequivalence in the control and intervention communities at baseline. The results may be useful for evaluators and researchers who seek to understand the impact of methodological factors on the interpretation of campaign effects.

Toward a Collective Framework on Verbal Aggression: Hierarchical and Antagonistic Processes

In the epilogue to this special issue, a hierarchical antagonistic process model is offered as a collective framework to explain the antecedents and consequences of verbal aggression described in the five preceding articles. The model proposes that the general traits of motivation to argue and verbal aggressiveness are second-order factors exerting top-down influence on more statelike subsidiary motives and attitudes. A test of the model (N = 743) found support for the proposed four-step process: Argumentation training increased motivation to argue, motivation to argue increased ability to argue, ability to argue increased self-esteem, and self-esteem decreased verbal aggressiveness. However, the indirect negative effect of motivation to argue on verbal aggressiveness was offset by a much larger direct positive effect. Belief systems theory was used to identify potential mediators of this positive effect and to explain other aspects of the verbal aggression process.