This is one in a series of posts on cognitive biases and how they apply to digital content and strategy. If you'd like to learn more about the thinking and experimental work behind these theories, I highly recommend Thinking, Fast and Slow, by Daniel Kahneman.
Confirmation bias is one of the most common and pervasive cognitive biases you're likely to see. It is the human tendency to preferentially accept information that appears to confirm already-held beliefs, and question evidence that calls those beliefs into question. Confirmation bias is particularly evident in the context of controversy. If you believe that something is true, and I appear with evidence that you're wrong, you're much more likely to question my evidence (or my motives in presenting it) than you are to change your mind.
For an extended (and passionate) presentation on confirmation bias and its effect on American history and politics, see The Political Brain, by Drew Westen. As Westen documents, confirmation bias played a significant role in presidential politics over the past 30 years. Westen also draws on behavioral research to provide the solution: confirmation bias is evoked when you confront a difference of opinion with evidence. The way past it is first to establish an emotional connection with your audience.
For example: let's say that you're developing content for an environmental activist organization. You have a set of content on global warming, and you're not interested in preaching to the choir. You want to convince global warming skeptics, but how do you go about that? If you present facts and figures, Westen argues, you will get nowhere. Your skeptical readers will believe that you're cherry-picking your data, or even that you're quoting from studies that were drawn up in service of a conspiracy.
Instead, you need to begin by connecting with your readers. Think emotional themes: the welfare of our children, our shared hope for the future, the beauty of growing things. Open with this content to establish a set of values you share with your readers, the skeptics included. Then, from there, you move on to aspects of your argument. Westen argues that you can make an evidence-based argument, but not right away. Opening with inspiration and closing with evidence gives you the best chance of success.
One last thing about confirmation bias: it applies to everyone, you and me included, but it's far easier to spot in others than it is in ourselves. It might be worth asking where your own confirmation biases lie—those are the places where your own thinking breaks down.