Commitment Bias

Participants evaluated the poor performance of a colleague. 50% were originally responsible for their promotion and 50% were not. 

Those originally responsible for promoting the colleague rated their performance more favourably than those who were not. 

When we commit to something, we often stick with it even if it becomes increasingly apparent we should not. 

See the full study here :

Bazerman, M. H., Beekun, R. I., & Schoorman, F. D. (1982). Performance evaluation in a dynamic context: A laboratory study of the impact of a prior commitment to the ratee. Journal of Applied Psychology67(6), 873.

Want to know more about biases?

Nostalgia effect

Lag Effect

Door in the Face Technique