Cognitive bias

A cognitive bias happens when someone makes a bad choice that they think is a good choice. This bias is an important part of the study of cognitive psychology. 
Cognitive biases do happen. Primitive humans and animals do things which seem foolish later. The scientific method limits the results of cognitive bias.
Cognitive bias is a natural consequence of our using "gut feelings" to make decisions when those decisions cannot be made rational because the evidence is not available.
The notion of cognitive biases was introduced by Amos Tversky and Daniel Kahneman in 1972. It grew out of their experience of people's inability to reason with numbers. Tversky, Kahneman, and colleagues showed several repeatable ways in which human judgments and decisions differ from rational choice. The heuristics people use are mental shortcuts which provide swift estimates. Heuristics are simple for the brain to compute but sometimes introduce "severe and systematic errors".