This thesis investigated the effect of still images (i.e., photographs) on engagement with a pro-environmental topic. A combination of exploratory (i.e., Q-methodology) and experimental study designs were used. By drawing on the elaboration likelihood model and appraisal theories of emotion, the research tested whether discrete emotions, elicited by an image and embedded within a related written text, influence message processing and, in turn, cognitive, affective, and behavioural engagement with the message topic. Research has only begun to assess the effect of discrete emotions on depth of processing. These early findings suggest that emotions that differ with regard to the cognitive appraisal of certainty will have differential effects on depth of processing. However, this nascent research has largely focused on incidental rather than integral emotions and has not examined the role of images as the antecedent to the emotion elicited. This thesis aims to fill this gap by assessing how related, emotive images influence depth of processing and overall engagement. Chapter 2 presents the results of a Q-method study that assessed community members' (N = 23) responses to categories of context-relevant images in terms of emotional response, personal relevance, and topic congruence. The study found that although images of oceans elicited positive emotions (e.g., serenity), most participants did not perceive such I acknowledge that copyright of all material contained in my thesis resides with the copyright holder(s) of that material. Where appropriate I have obtained copyright permission from the copyright holder to reproduce material in this thesis and have sought permission from coauthors for any jointly authored works included in the thesis.