The primary aim of this research was to examine the influence of temporary mood states on factual and interpersonal skepticism. Based on recent affect-cognition theorising and research on credibility judgment, 7 studies predicted that negative moods increase and positive moods decrease skepticism, because of the information-processing consequences of these affective states. First, three studies examined the influence of mood on factual skepticism toward urban myths and legends (Study 1) and novel and familiar general knowledge claims (Studies 2-3). Contrary to predictions, Study 1 found that sad participants were less skeptical than happy participants towards urban legends, possibly due to the negative valence of the claims. Because the feeling of familiarity has been shown to be an important determinant of truth, Studies 2-3 examined the influence of mood and familiarity on skepticism. Consistent with information processing theories of mood, happy participants were more likely than sad participants to give credence to familiar general knowledge claims (Study 2), even when given explicit feedback about their actual truth or falsity during initial exposure to claims (Study 3). The remainder of this thesis extended these findings to interpersonal judgments. Studies 4-5 found that sad participants were more skeptical of the genuineness of facial expressions of emotion compared to happy participants. Studies 6-7 examined whether sad participants might also show greater lie detection accuracy. In Study 6, happy, sad and neutral-mood participants judged the credibility of targets honestly or deceptively describing their emotional reaction to an affectively-laden film, but no evidence was found of mood induced differences in deception detection accuracy. However, in Study 7, sad participants were more skeptical than happy participants about the veracity of videotaped individuals honestly or deceptively denying their involvement in a mock crime (a theft), and showed greater accuracy at discerning lies from truths. This dissertation contributes to the affect-cognition literature by demonstrating that not only may sad moods lead people to be more skeptical, but they may also confer an advantage at detecting deception. The implications of these findings for everyday credibility judgment and for contemporary theories of affect and cognition are considered.

This dissertation describes the credibility judgment process using social psychological theories of dual-processing, which state that information processing outcomes are the result of an interaction “between a fast, associative information- processing mode based on low-effort heuristics, and a slow, rule-based information processing mode based on high-effort systematic reasoning” (Chaiken & Trope, 1999, p. ix). Further, this interaction is illustrated by describing credibility judgments as a choice between examining easily identified peripheral cues (the messenger) and content (the message), leading to different evaluations in different settings. The focus here is on the domain of the Web, where ambiguous authorship, peer- produced content, and the lack of gatekeepers create an environment where credibility judgments are a necessary routine in triaging information. It reviews the relevant literature on existing credibility frameworks and the component factors that affect credibility judgments. The online encyclopedia (instantiated as Wikipedia and Encyclopedia Britannica) is then proposed as a canonical form to examine the credibility judgment process. The two main claims advanced here are (1) that information sources are composed of both message (the content) and messenger (the way the message is delivered), and that the messenger impacts perceived credibility; and (2) that perceived credibility is tempered by information need (individual engagement). These claims were framed by the models proposed by Wathen & Burkell (2002) and Chaiken (1980) to forward a composite dual process theory of credibility judgments, which was tested by two experimental studies. The independent variables of interest were: media format (print or electronic); reputation of source (Wikipedia or Britannica); and the participant’s individual involvement in the research task (high or low). The results of these studies encourage a more nuanced understanding of the credibility judgment process by framing it as a dual-process model, and showing that certain mediating variables can affect the relative use of low-effort evaluation and high- effort reasoning when forming a perception of credibility. Finally, the results support the importance of messenger effects on perceived credibility, implying that credibility judgments, especially in the online environment, and especially in cases of low individual engagement, are based on peripheral cues rather than an informed evaluation of content. / text