Here's why:
* Titles are generally not capitalized unless they are part of a formal name: You would capitalize "Professor Smith" or "Associate Dean Jones," but not the general title itself.
* "Associate professor" is a descriptive title, not a proper noun: It doesn't refer to a specific person or place.
Exceptions:
* You might capitalize "Associate Professor" when it appears at the beginning of a sentence or in a formal document like a diploma. However, it's generally considered more appropriate to avoid capitalization in most cases.
Example:
"Dr. Jones is an associate professor at the university."