This article relies on U.S. 2‐wave panel data to examine the role of social media as a sphere for political expression and its effects on political participation. Informational uses of social media are expected to explain political expression on social media and to promote political participation. This study clarifies the effect of using social media for social interaction in fostering political expression and participation processes. Results indicate that social media news use has direct effects on offline political participation and indirect effects on offline and online political participation mediated via political expression. Furthermore, social media use for social interaction does not have direct influence in people's political engagement, but rather an indirect effect by means of citizens expressing themselves politically.

Using two quantitative methods, this study sought to understand whether user-generated posts would vary in frequency of incivility, impoliteness, and deliberative attributes on Twitter versus Facebook. A quantitative content analysis ( N = 1458) revealed that posts responding to the White House’s tweets were significantly more uncivil and impolite and less deliberative than responses to White House Facebook posts. Also, comments on posts that concerned sensitive topics (such as same-sex marriage) were more uncivil, impolite, and deliberative than comments regarding less sensitive topics (such as technology). An experiment ( N = 198) showed that people were more deliberative when responding to White House Facebook posts, compared with White House tweets, but no differences were found for incivility and impoliteness. Results suggest that both the varying affordances of the two platforms and the fact that the two sites may attract different types of people might explain these results.

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In-vehicle information systems (IVIS) can be controlled by the user via direct or indirect input devices. In order to develop the next generation of usable IVIS, designers need to be able to evaluate and understand the usability issues associated with these two input types. The aim of this study was to investigate the effectiveness of a set of empirical usability evaluation methods for identifying important usability issues and distinguishing between the IVIS input devices. A number of usability issues were identified and their causal factors have been explored. These were related to the input type, the structure of the menu/tasks and hardware issues. In particular, the translation between inputs and on-screen actions and a lack of visual feedback for menu navigation resulted in lower levels of usability for the indirect device. This information will be useful in informing the design of new IVIS, with improved usability. STATEMENT OF RELEVANCE: This paper examines the use of empirical methods for distinguishing between direct and indirect IVIS input devices and identifying usability issues. Results have shown that the characteristics of indirect input devices produce more serious usability issues, compared with direct devices and can have a negative effect on the driver-vehicle interaction.