A mental structure that people use to organize their knowledge about the social world around particular themes and subjects which influences the information that people notice, think about, and remember would best be described as.

The answer is schemas.

Explanation:

Schemas can be understood as "blocks of information" about different aspects of the world. For example, a young child might have numerous schemas about a car: it has wheels, it's large in size and runs fast. Later he might see a motorbike and call it a car, because his schemas apply. Schemas then can be modified in order to learn new information (motorbikes have two wheels, they are smaller...).