Final answer:
Confirmation bias is the phenomenon where the researcher is unconsciously seeking data specifically to justify a preconceived belief. It is the tendency to focus on information that confirms one's existing beliefs.
Step-by-step explanation:
Confirmation bias is the phenomenon where the researcher is unconsciously seeking data specifically to justify a preconceived belief. It is the tendency to focus on information that confirms one's existing beliefs. For example, if a researcher believes that a certain treatment is effective, they may selectively look for data that supports their belief while ignoring contradictory evidence. Confirmation bias can impact the validity and reliability of research findings.