When we are motivated to form an impression, in general, or one of a particular valence, more specifically- we unintentionally activate a biased information processing system that will give us exactly what we are looking for. The on-line processing mode will encode information differently, and will both retrieve early informational entries more often and bias subsequent evaluations based on an unrepresentative recall of information, contra to what the complete, objective information set would offer. This is the science behind what many of us knew all along: if you really want to be accurate, you can't go in with expectations! Easier said than done...