Confirmation bias: Why we see what we want to see

Confirmation bias is our tendency to search for, interpret, and remember information that confirms our existing beliefs/opinions while overlooking contradictory evidence. It’s one of the most pervasive cognitive shortcuts (heuristics) affecting most people’s daily decisions.

Confirmation bias has deep evolutionary roots. Our ancestors didn’t have time to carefully weigh every piece of evidence; quick decisions often meant survival. The brain evolved to use heuristics that conserve cognitive energy and calories. Because processing information requires significant mental effort, our minds developed efficient strategies: stick with what you already “know” works, and filter out conflicting information. This usually generates “good enough” decisions quickly, which helped us navigate dangers and opportunities without ‘analysis paralysis’.

Imagine you’re convinced that a particular route to work is fastest. One morning, you hit unexpected traffic and arrive late. Instead of reconsidering your route choice, you think, ‘This is unusual, there must have been an accident’. The next day, you arrive on time and think, ‘See, this route really is the best’. You remember the smooth commutes vividly while dismissing the delays as anomalies. Meanwhile, you’ve never actually tested alternative routes because you’re already ‘certain’ yours is quickest.

We follow news sources that align with our politics, interpret ambiguous feedback from our boss based on our existing opinion of them, and notice evidence supporting our favourite sports team’s superiority while forgetting their losses.

Understanding confirmation bias doesn’t eliminate it, but recognizing when we might be cherry-picking evidence can help us make more balanced decisions, even if it costs us a few extra mental calories and a few extra seconds.

Here’s a powerpoint to help teach this topic to your IB Diploma Psychology class…

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