Visitor attitude is a critical component that affects potential tourists’ decision making and, ultimately, destination choice. Tourism marketers seek to influence prospective visitors’ attitudes through reinforcing existing associations with the destination or creating new associations. In addition, marketers use persuasive marketing stimuli to affect associations with the destination. In particular, the design or characteristics of marketing stimuli such as the perceived credibility and emotive aspects exert a significant impact on potential tourists’ attitudes towards, and associations with, the destination. Furthermore, the characteristics of marketing messages can influence tourists’ cognitive and affective evaluations of a place, confidence in and consideration of a holiday destination. Social psychologists believe that message characteristics influence attitude via three dimensions of thinking: the amount of thought; valence of thinking; and thought confidence. The assertion is that the cognitive engagement with a message and the favourability of thoughts, along with an individual’s confidence in their thoughts predict attitude. However, tourism scholars have investigated only the first two dimensions of thinking: the amount and valence of thoughts. Therefore, the role of thought confidence has been understudied in the tourism context. Thought confidence forms part of the self-validation hypothesis, which asserts that thought generation is not enough to influence attitude, rather people need to feel confident in their thinking (Petty, Briñol & Tormala, 2002). Although social psychologists have examined the influence of a number of variables on attitude, the role of emotion, and specifically emotional arousal, is not well discussed in the self-validation hypothesis literature. This thesis aims to fill the gap in the tourism and social psychology literature through adapting the main elements of previous theories of attitude – notably the elaboration likelihood model and heuristic systematic model - along with the self-validation hypothesis to study the effect of the three dimensions of thinking on attitude towards a less known tourism destination, Iran. To achieve that aim, this research applies a two-stage sequential design to manipulate the emotional arousal and perceived credibility of tourism stimuli and measures the effect of the three dimensions of thinking on attitude. In order to manipulate the characteristics of an advertisement of Iran, a mock tourism marketing stimulus was created in Stage I. This stage involved two focus groups and Delphi panels to select the images and video segments of Iran to be included in a mock advertisement. The Delphi panellists and focus group members selected nine images of historical monuments, nature, and food along with segments of current videos of Iran to be included in the mock advertisement. Subsequently, the mock advertisement, that was created as a combination of selected photos and segments of videos was pilot tested from a representative sample of Australians to check the emotional arousal and perceived credibility manipulation. In particular, FaceReader, skin conductance, a questionnaire and post-hoc interviews were applied to assess the emotional arousal and source credibility manipulation. The results indicated that while the video with light rhythmic music was considered as a highly emotionally arousing video, the same video but without music was regarded as a low emotionally arousing advertisement. In addition, “A solo female traveller who visited Iran in 2017” was considered as a highly credible source and “A travel agency in Iran for promotional purposes” was believed to be a low credible one. Stage II is the experiment phase (N = 416). In this stage, participants were randomly assigned to a two (emotional arousal: high or low) × two (source credibility: high or low) between subject factorial design. The results indicated that all three dimensions of thinking, the amount and valence of thoughts in addition to thought confidence, can positively affect potential visitors’ attitude towards the destination. The findings of the research also revealed that participants were more cognitively engaged with the stimuli and confident in their thoughts, and generated more positive thoughts and more favourable attitudes about Iran as a destination when the tourism stimulus was perceived as highly credible and evoked high levels of emotional arousal. This thesis provides a number of contributions. Theoretically, the study adds value to the body of literature in social psychology by examining the role of emotional arousal in explaining thought confidence and attitude. There is also a contribution to the tourism literature by adapting the self-validation hypothesis from social psychology and adding a metacognitive aspect to attitudinal research in the tourism context. This research is also novel in exploring the effect of source credibility on attitude from a metacognitive perspective in the tourism literature. Methodologically, this research contributes to the tourism literature by its novel application of physiological tools - FaceReader and skin conductance - to analyse emotions elicited in response to tourism advertisements. From a practical perspective, the present study provides valuable feedback for destination managers and marketers, especially for the design of marketing stimuli. Managers of less-known destinations need to create emotionally arousing advertising in order to make potential visitors cognitively engaged with the stimuli, make them confident in their thoughts and thus exert a positive impact on subsequent attitude towards the destination. Furthermore, Iranian tourism practitioners can rely on the content and stories shared on social media by real tourists as credible references to encourage potential visitors to travel to their destination.