Attitude, like others have mentioned is given by:

(upvotes cast - downvotes cast) / (upvotes + downvotes)

If you want to see exactly how it is done, here is the code reference. Basically, it is just a number between -1 and 1 (-100% to 100%) based on the votes you have made. It can be different on different instances depending on what has federated to where. For example, on instances with downvotes disabled, everybody has a 100% attitude!