https://www.psychologytoday.com/blog/intimate-portrait/201703/self-deception-helps-us-accomplish-goals
Recent research by Robert Trivers and his colleagues sheds light on just how useful our ability to delude ourselves can be. In a clever experiment, participants were asked to write a speech about a character after watching a series of videos of him engaging in positive, neutral, and negative actions. Sometimes the participants saw the character behaving positively before acting in a negative way and vice versa. Before watching the videos, the participants were randomly instructed to try to persuade others to form either a positive, neutral, or negative opinion of the character. A financial reward was offered to participants who wrote the most persuasive messages. Participants in turn watched the videos in a biased manner. For instance, if their goal was to write a positive message the participants lost interest in watching the rest of the videos when they first saw the character helping someone in distress. After seeing evidence to support their goal, they’d seen enough. However, if their goal was to write a positive message and the first few videos showed the character behaving poorly, they kept watching until they saw him engage in a positive action—they held out until they saw what they wanted to see.
The participants also formed judgments about the character consistent with the message they were asked to write. For example, those who were asked to write a positive passage actually saw him in a more positive light (and they thought other people would see it the same way). More importantly, people who let their goals influence their beliefs and watched the videos in a biased manner also created the most persuasive messages. This study shows that goals can influence how we take in information, shape what we believe to be true, and help us get others to see the world as we do. It appears that self-deception plays an important role in helping us accomplish our goals.
The next time you encounter someone who fails to see reason, they’re probably not being any more or less unreasonable than you—their goals simply differ from yours. Facts be damned, it’s our goals that matter.