Jean was at the mall with her family. She tried on a pair of shoes she really wanted. Her parents told her that they could not afford the shoes and walked out of the store. For a moment, Jean thought of running out of the store with the shoes on, but her parents had taught her at a very young age that stealing was wrong. A split-second after thinking about stealing the shoes, Jean began to feel incredibly guilty about even having the thought. Which part of Jean's personality squelched her desire to steal the shoes?

The id: the most primitive of all 3 structures and the one that forms first during child development. The id is concerned with immediate gratification of needs and urges. (It's instinctive)
The super-ego: It's concerned with moral rules, it's like one's conscience, or in other words "the moral compass". This structure is the one that makes us feel guilty when we do something wrong.
The ego: is the structure in charge of mediating with the id and the super-ego, so it's the one that keeps things in balance between the other two. (it's rational)

In this example, Jean tried a pair of shoes she really wanted but her parents couldn't afford them. For a moment, Jean thought of running out of the store with the shoes on but her parents taught her that stealing was wrong. So now Jean feels guilty about having had that thought.

We can notice that when Jean thought about running out of the store with the shoes on, it was the id who had taken over (since it was concerned with instant gratification), however, she knew that stealing was wrong and he decided not to steal (the ego mediating). However, she feels guilty because her conscience is telling her that she had a bad thought since she knows well that stealing is wrong.

Thus, the super-ego is the one that squelched her desire to steal the shoes and is now making her feel guilty.