In psych class, I recall learning about a cognitive bias where people are inclined to use all information available to them when making a decision, even if some of the information would be better ignored.
I believe the example given was a study in which participants were asked to evaluate the (college?) application of a candidate. Some participants were given just the conventional application information, while others were additionally given irrelevant information in the form of a portfolio of the candidate's elementary school artwork. The finding was that the artwork influenced the participant's decisions when it was provided.
What I don't remember is what this bias is called!