color context.

The different companies in the world decide on the colors that they make their products. These two objects, the school bus and the base of the lamp post, are yellow because they are objects that need to stand out. The school bus needs to stand out for the safety of the students that are riding it. The base of the lamp post needs to stand out because if it didn't stand out then people could possibly run their cars into it. If these objects were any different color they might not stand out quite as much and people might get hurt....it's a safety thing.