In Japan, Korea, and to a less extent in a few other countries some people believe in a connection between a person’s blood type and their personality. There is no scientific basis for this belief but it still persists.

An essay on May 2021 TOK Essay Prescribed Title #6 needs to investigate how bias plays a positive and negative role in the pursuit of knowledge.
Consider possible biases in this RLE:
- People believing / not believing in the theory because of how they feel about the traits associated with their blood type
- People believing in the theory because they trust someone who believes in it
- People not believing in the theory because they trust someone who does not believe in it
- The role of bias in popular publications about the blood type theory
- The role of bias in scientific publications about the blood type theory
- How the blood type theory has affected some people in the workplace
- How the blood type theory has affected some people’s personal lives