Researchers collected 180 news stories from university students and the Internet about stupid behaviors. Later, students rated the intensity of the stupidity from those stories.

After this research they concluded that:

“Confident ignorance” is when people engage in risky actions for which they lack the skills. For example, burglars thought they were stealing mobile phones. But actually stole GPS tracking devices. This allowed the police to find them.

“Lack of control” results from addictive behavior. For example, the person who cancelled a meeting with a friend because they couldn’t pull themselves away from a video game.

“Absentmindedness – Lack of practicality” refers to instances when people fail a practical task. For example, someone inflating car tires too much.

These actions can make us look stupid in the eyes of other people.

This research has limitations in that it relies on the judgments of a group of students in Hungary.

Aczel, B.; Palfi, B.; and Kekecs, Z. (2015). What is stupid? Intelligence, 53, 51-58 DOI: 10.1016/j.intell.2015.08.010