The greater the person's level of cognitive engagement with an issue the more likely he or she is to be exposed to and comprehend in a word, to receive political messages concerning that issue.
People tend to resist arguments that are inconsistent with their political predispositions, but they do so only to the extent that they possess the contextual information necessary to perceive a relationship between the message and their predispositions.
The more recently a consideration has been called to mind or thought about, the less time it takes to retrive that consideration or related considerations from memory and bring them to the top of the head for use.
Individuals answer survey questions by averaging across the considerations that are immediately salient or accessible to them.
Source: Zaller, John R. (1992) The Nature and Origins of Mass Opinion. Cambridge, UK: Cambridge University Press.