Confirmation Bias

Subjects in favor ad against capital punishment were exposed to two ficticious studies, one supporting and one opposing capital punishment. 

Each side rated those results and procedures that confirmed their own beliefs to be more convincing and credible.

We tend to seek, interpret and prefer information that reinforces our beliefs.

See the full study here :

Lord, C. G., Ross, L., & Lepper, M. R. (1979). Biased assimilation and attitude polarization: The effects of prior theories on subsequently considered evidence. Journal of Personality and Social Psychology, 37(11), 2098–2109.

Want to know more about biases?

Confirmation Bias

Identifiable Victim Bias

Base Rate Fallacy

Decoy Effect