Doctor of Philosophy (PhD)


Mass Communication

Document Type



Some contemporary theories in political science maintain that public lobbying is merely an expression of latent and resolute public opinion that is communicated to policymakers. Other theories contend that the public is highly manipulable and that public lobbying by extension can be considered a form of strategic framing that takes place through the news and paid media. Both theoretical approaches specify a function for words or text but are silent on the influence of photographs or images. In this dissertation, I hypothesize that environmental public lobbying operates as strategic framing and that text and photographs have unique and discrete effects on public opinion and policy action. In a study on the effects of greenwashing, I examine how photographs and text influence aggregate public concern for the environment, public preferences on specific public problems and congressional committee action on environmental issues. Time series agenda-setting models show that photographs and text do have differential effects on public salience and policy action: public concern is largely compelled by words, whereas photographs drive policy attention. In a related experiment, findings suggest that images may directly influence specific policy preferences, but that there is no evidence of exclusively photographic framing effects. Words on the other hand are capable of directly changing opinions and also show evidence of framing effects.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Tim Cook