Per

Here I am trying to put words on something I just discovered that science already invented.

I present to you, the fundamental attribution error of social psychology — explaining reality based on the personality of people without taking in regard social context and situation.

Example:
Let’s say I am generally regarded as a person that is “open to new people”. Then I temporarily become upset for a week due to work-related problems. During this week I happen to meet a new person to whom I pay little attention. This person is unlikely to perceive me as a person that is “open to new people”, even though over time that statement is more true than false. The specific context and situation causes me to act in a way that I rarely do, but as this is all the person sees he or she will believe that I am in fact NOT “open to new people”. The behavior will be attributed to me as a person instead of the specific context in which it happened. The stronger the situational factors during which you meet a person the larger the number of attribution errors you are likely to make.