There are two competing ideas on the process that governs the formation and maintenance of beliefs: 1) people maintain a belief because they have limited access to opposing beliefs, or 2) because they actively filter information in a way that avoids conflicting views. A new meta-analysis of past studies confirms the existence of active avoidance; when people are offered an opposing viewpoint, they will ignore it in favor of a supportive viewpoint in two out of three instances.

The meta-analysis was performed by researchers at the University of Illinois and the University of Florida. They managed to identify a total of 91 relevant studies that included nearly 8,000 participants. The studies were all on the subject of selective exposure, or how people filter out incoming information based on how it jibes with their current beliefs. The studies attempted to determine whether people wanted to view or read something that either supported their point of view or challenged it.

Analysis of the studies shows that people are almost two times more likely to select information that is congenial to their current beliefs and behaviors than they are to pick information that opposes them. That is to say, when offered material containing views that were contrary to their beliefs (either in article or broadcast form), people had only a one-in-three chance of taking a closer look at that information.

Perhaps unsurprisingly, the bias against conflicting views was exaggerated when the information concerned political, religious, or ethical issues. Also in the "no surprise" department was the finding that individuals with close-minded personalities selected information that is aligned with their views 75 percent of the time (for more typical people, the number was 67 percent). The study also found that people who are unsure of their beliefs are actually more likely to avoid conflicting views.

The authors noted certain factors that prompt people to seek opposing opinions. For example, politicians and others who must publicly defend their beliefs can only be prepared by knowing their ostensible enemy, and they will seek to process and understand an opposing viewpoint. This exposure, however, can help existing beliefs evolve and become stronger.

The study also showed that age correlates with a bias towards congenial information: younger children were more apt to investigate opposing viewpoints, while older children were increasingly likely to close them out.

This study provides a great deal of information about the way people filter information presented to them, but there is little it can say about the way information is perceived and processed once it is accepted for closer examination. The researchers note that any bias towards information recalled from memory is somewhat smaller than the one observed when information is selected for processing. However, bias during processing has yet to be thoroughly investigated, and doing so would be the logical next step in understanding information bias.

Psychological Bulletin, 2009. DOI: 10.1037/a0015701