We See Bias in Others More Than Ourselves
You have now read about confirmation bias, availability bias, the Dunning-Kruger effect, framing effects, and attribution errors. There is one further bias that directly undermines the value of all that knowledge: the bias blind spot — the tendency to see cognitive biases operating in others while failing to recognise them in yourself.
The bias blind spot was named and documented by Emily Pronin, Daniel Lin, and Lee Ross at Princeton University in a 2002 paper published in Psychological Science. In their studies, participants consistently rated themselves as less susceptible to a list of cognitive biases than the average person — a statistical impossibility given that the average person is, by definition, average. When subsequently shown the data demonstrating this, most participants accepted that other people were failing to recognise their biases, while maintaining that their own self-assessment was accurate.
Why Self-Exemption Persists
The bias blind spot is not simply a specific form of the general overconfidence bias (though it overlaps with it). Pronin and colleagues identified a specific mechanism: people evaluate their own susceptibility to bias through introspection — examining their feelings, motivations, and reasoning processes. But introspection is unreliable as a detector of bias, because biases typically operate below the level of conscious awareness. They feel like objective perception, not like bias.
When you observe another person making an obviously biased decision, the bias is externally visible in their behaviour or reasoning. When you are the person making the decision, the internal experience does not feel biased — it feels like clear thinking.
The Introspection Illusion
Pronin termed this the "introspection illusion": people believe that looking inward gives them privileged, accurate access to their own mental processes. In practice, introspective reports are often confabulations — post-hoc narratives constructed to explain behaviour that was actually produced by processes the person has no direct access to.
This matters greatly for financial decision-making. An investor who genuinely believes they are being objective, having "thought it through carefully," may be no less subject to confirmation bias, framing effects, or availability bias than one who makes impulsive decisions. The sense of having deliberated is not evidence of having deliberated correctly.
The Implications for Debiasing
The bias blind spot creates a specific challenge for any debiasing programme: simply informing people about cognitive biases often increases their confidence in their own objectivity rather than improving it. They learn the concepts, apply them to others they see as less careful, and conclude that they personally are not subject to the biases they've learned about.
Research by Pronin and colleagues showed that people who were told about a specific bias and then made a decision involving that bias were less likely to attribute the bias to themselves than people who had not been told about the bias beforehand. Knowledge, paradoxically, reinforced the illusion of immunity.
The implication is that the goal should not be to become convinced of one's own objectivity through education. It should be to build external structures that produce good decisions regardless of whether any particular decision feels biased in the moment.