To understand the process of persuasion, it is useful to consider two ways we process information. Think about the last time you bought a can of soda. Did you carefully research brands, or did you reach for the can that had the most appealing advertising? If we’re honest, we’ll admit glitzy ads and catchy slogans have an influence on our choices as consumers. We often rely on automatic processing, a relatively superficial consideration of evidence and information making use of heuristics.

Automatic processing takes little time and low effort, so we tend to use it for processing persuasive messages related to topics we don’t care much about. The disadvantage is that it lets us be fooled easily by a variety of tricks. Now consider the last time you chose a place to live. You probably sourced experts who knew something about the area, gathered information about prices, and considered the costs and benefits of renting versus buying. You were engaging in more effortful controlled processing, a detailed consideration of evidence and information relying on facts, figures, and logic.

One of the best predictors of whether people will use an automatic or controlled process for reacting to a persuasive message is their level of interest in it. Interest levels reflect the impact a decision will have on your life. People who are well informed about a subject area are more likely to use controlled processing strategies. They have already thought through various arguments for or against a specific course of action. Another factor that influences whether people use an automatic or controlled processing strategy is the characteristics of the message itself. Messages provided through richer communication channels encourage more deliberative processing.