Richard E. Petty, Derek D. Rucker, George Y. Bizer, and John T. Cacioppo discuss the Elaboration Likelihood Model (ELM) model of persuasion. According to this model, there are two basic responses to a new message - thinking more about the message AND relying on heuristics to quickly respond to the message. Heuristics are rules of thumb--cognitive shortcuts that can be as simple as "the author is an expert, I should listen to her." I will note that I use the term 'cognitive' to refer to those processes that are concerned with truth and falsity. Heuristics are primarily identified by their generality and simplicity. According to the ELM, message recipients that are high in motivation and ability are more likely to think about a message--elaborating it and increasing the likelihood that attitudes formed for or against the message will be lasting.
A chart detailing the central (more elaboration) and peripheral (more use of heuristics) routes to persuasion can be found on the third page of the PDF document that I link to below. This article also includes discussion of empirical research surrounding different postulates of the ELM - correctness, an elaboration-continuum, multiple roles for variables, objective-processing, biased-processing, trade-off between central and peripheral processing, and attitude-strength.
