A consistent theoretical and practical challenge in the design of socio-technical systems is that of motivating users to participate in and contribute to them. This study examines the case of Everything2.com users from the theoretical perspectives of Uses and Gratifications and Organizational Commitment to compare individual versus organizational motivations in user participation. We find evidence that users may continue to participate in a site for different reasons than those that led them to the site. Feelings of belonging to a site are important for both anonymous and registered users across different types of uses. Long-term users felt more dissatisfied with the site than anonymous users. Social and cognitive factors seem to be more important than issues of usability in predicting contribution to the site.

The relationship between social media use and youth’s political participation has been extensively studied. However, explanations for youth’s online collective political activism have been less explored. Previous studies have used the concept of internal political efficacy to examine the relationship between social media and political participation. However, this concept only explains individual political participation, while many political actions are performed collectively. Based on Social Cognitive theory this study propounds the concepts of online political self- and collective efficacy and explores their relationship to online collective political activism. Findings of a survey of members of three activist groups of a US Mid-Western university ( n = 222) suggest that a correspondence exists between efficacy perceptions and the level of agency at which the political activities are performed online. Also, online collective efficacy perceptions influence individuals’ participation in online collective actions, but this relationship is moderated by the perceived interdependence of the actions.

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The use of social media sites for political expression has added a new layer to the study of political discussion. In this type of user-generated content applications, interpersonal and mass-mediated types of communication converge in one medium. Therefore, in this study, we bring together insights from interpersonal communication theories and mass communication models that predict online expression, adding explanatory power to this form of political participation. Specifically, we contribute to the understanding of social media political expression by examining the influence of communication competence and expected outcomes on expressive behaviors. Results of a representative survey of the adult urban population of Colombian Facebook (n = 598) and Twitter (n = 185) users, suggest that social media communication competence and expected status, novelty, and social outcomes influence political expression on social media. Furthermore, users' social media political expression expected outcomes through Facebook and Twitter differ. This study illustrates the important role that interpersonal communication factors have for social media political discussion, and the difference between users' expectations when they express their political views through different social media platforms.

This study examines, through a content analysis of the census of news stories posted in a Colombian online political community, how status cues and informational cascades shape participation in online political discussions. Specifically, it looks at how the authors' news stories posting increase rate, the number of news story sources, the velocity at which comments to a news story start to appear, and the comment interactivity affect discussion participation. Results suggest that cues that signal expertise influence participation, while discussion among users also influences the decision of others to participate. However, the effect of these variables is stronger for some topics. Implications for the constitution of public spheres are discussed.

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OBJECTIVE: To document the evidence about marketing of ultra-processed foods and “non-alcoholic” beverages in Latin America. METHODS: We performed a structured search of quantitative and qualitative studies in PubMed, SciELO and LILACS, published between January 2000 and May 2017 and conducted in Latin America. We conducted a quality assessment following a standardized tool and a thematic analysis to identify key typologies of marketing across studies RESULTS: Out of 521 studies screened by title and abstract, we included 36 in this review; 27 of them analyzed television advertisement. Other marketing channels studied were food packaging, point of sale and outdoor advertisement. Studies found television advertises foods and beverages that are mostly ultraprocessed foods and have low nutritional value, particularly those promoted during children’s programming. We also observed children have a literal interpretation of images printed on food packaging, so this can be deceiving. Several studies also found proximity to unhealthy foods may increase their consumption. Finally, the thematic analysis identified the following typologies of food marketing: a) television advertisement, b) food packaging marketing, c) marketing strategies at points of sale and d) other marketing strategies. We found almost no advertisements for unprocessed or minimally processed foods such as fruits and vegetables. We did not find any studies on digital marketing conducted in the region. CONCLUSIONS: This review found that the main channel of food marketing was television advertising. This synthesis provides insights to the challenges unhealthy eating represents to the public health of Latin America and identifies knowledge gaps to guide future research.