I'm looking for a word or phrase

[IDemo]

to describe the misuse of a single character trait, behavior or belief to define the whole person or entity. Let's say, for example, that an individual who engages in periodic motocross racing on weekends is characterized as reckless, including within areas completely unrelated to racing. It's akin to binary thinking, Manicheanism and religious or political extremism, though not necessarily as absolute.

"Prejudice" isn't precisely what I'm after, though it's often the result of such thinking.

Thanks ahead of time for any suggestions.