In the above quote, Leonardo da Vinci addresses the tendency that we notice the errors in others more easily than in ourselves. This tendency is based on three different cognitive biases:

• Bias blind spot [1,2]: “I consider myself to be very objective and not influenced by biases.”

• Naïve realism [3]: “I believe to see the world around me objectively and that people who disagree with me must be uninformed, irrational, or biased.”

• Naïve Cynicism [4]: “I expect that the judgments of others will have a motivational bias and therefore will be biased toward their self-interest.”

These three are only a small amount of about 185 cognitive biases to which we as humans are subject sometimes more and sometimes less. Since they often happen subconsciously, they are usually not even noticed at all.