Marvin feels that all people who wear glasses are very smart and love to read. He does not stop to consider that some people may have medical conditions that contribute to needing glasses. It seems that Marvin's thinking about people with glasses is based on a

Stereotype

Explanation:

The stereotype has to do with a general perception of a particular group of people. It involves ascribing a particular habit or attitude to such people when they are in a group. A group that is usually stereotyped normally have things in common, example includes;

Stereotyping based on gender Stereotyping based on nationality Stereotyping based on religion, etc.

Marvin is in the school of thought that people that wear glasses are smart and that is his belief. He never considered that the use of glasses can be ascribed to a medical condition. Here, Marvin is stereotyping people that wear glasses by categorizing them to only smart people.

The belief of Marvin that all people who wear glasses are very smart and love to read is a case of stereotype.