This type of cognitive error in thinking is called overgeneralization.
When you tend to make conclusions based on only small number of facts or instances then it refers to over generalisation. When to make decisions or frame statements or conclusions based on fewer information or facts it leads to over generalisation. This kind of over generalisation will make oneself feel dissatisfied and think that all will dislike him.
The main thing that helps you to eradicate this is to know one’s own potential or ability. In the given example, the student who has been doing very well in psycology receives a comment the the past exams that makes him feel that he is going to get fail in the course which is an example of overgeneralization.
