London, Nov 13 (IANS): While it is good for students to be self-confident in class, unrealistic perceptions of their academic abilities can be harmful, says a study.

Such unrealistic airs damage a child's relationship with others in the classroom, found the study.

"There is more to being labelled a nerd than just academic achievement. I really got interested in the question of whether it is OK to brag about achievements in class or if you should rather not display your achievements in the classroom," said Katrin Rentzsch of the University of Bamberg in Germany.

But that line of thinking led her to something different from bragging, something psychologists call "self-enhancement" -- when a person feels unrealistically superior to someone else.

The character Sheldon on 'The Big Bang Theory' is a typical example of self-enhancement.

"Although Sheldon is a smart person and receives respect for his scientific work, he still thinks that he is even smarter, brighter, or much better as compared to how he is perceived by others," added Rentzsch.

The researchers asked each student to rate their classmates, in terms of their likeability and of their feelings of academic superiority.

They then compared those ratings with the students' grades in maths, physics, German, and English.

"The more a student felt unrealistically superior to a specific other student, the less he or she was liked by the other student in return," said the researchers.

The study appeared in Social Psychological and Personality Science.