Cognitive prejudice, more commonly referred to as cognitive bias, is a type of judgement derived from illogical means and inaccurate grounds. In society, people are said to fabricate their own "subjective social reality", which is derived from their personal and relative perception of reality.
This perception of social reality, which is rarely objective, tends to become the substratum for which people base their social behaviours and actions. Due to this skewed or distorted sense of reality, cognitive biases are formed. This results in prejudice, irrationality and false judgement.
This process of cognitive biases are usually a byproduct of the snappy interpreting and internalising process. This is how we are often lead to error with said judgements.
We are constantly attempting to simplify and make sense of the information we are processing, and cognitive bias is simply a technique of reaching an ends with relative speed.
There are many factors which influence cognitive bias, including emotions, social pressures, peer pressures, and the overall limitations of the human brain which prohibit us from processing information entirely in all it's accuracy, so it finds itself in the midst of these erroneous short cuts.
I hope this helps.