What is it called when a person seeks to compare themselves to others? What is it called when a person consciously or unconsciously looks for similarities and differences in other people's reasoning, behavior, actions or past events and compares them with his/her own traits? I.e., Noticing them, with or without reacting, relating or comparing yourself with others.
Cognitive Bias


  A cognitive bias  is a pattern of deviation in judgment that occurs in particular situations. Implicit in the concept of a "pattern of deviation" is a standard of comparison; this may be the judgment of people outside those particular situations, or may be a set of independently verifiable facts.


One being:  


  Social comparison bias can be defined as having feelings of dislike and competitiveness with someone that is seen physically, or mentally better than yourself.


There are other types of bias that would be appropriate to cover what you have asked in your question, I suggest having a look. For a list of cognitive biases.

This question What are the possible causes of pettiness? and answer touches upon some of the reasons people compare themselves to others.