Base Rate Fallacy

85% of cars are blue and 15% are green. A man witnesses a hit and run and says the car was green. he can accurately identify the colors 80% of the time.

What are the chances the car is green? 

Usually, the people respond that the probability is 80%; when actually the correct answer is 41%.

We tend to assign greater value to specific information and ignore base rate information. 

See the full study here :

Bar-Hillel, M. (1980). The base-rate fallacy in probability judgments. Acta Psychologica44(3), 211-233.Bar-Hillel, M. (1980).

Want to know more about biases?

Spotlight Effect

Bandwagon Effect

Nostalgia effect

Focusing Illusion