Sometimes they do. It depends on which part of the brain was damaged. “Semantic” information about words and facts is stored in a different place than “episodic” information about particular events.
So “[semantic amnesia](https://en.wikipedia.org/wiki/Semantic_amnesia)” *is* a thing. (In fact, it’s not even a particularly uncommon thing, since it’s famously an early symptom of Alzheimer’s Disease.) If you don’t hear about it very often, it’s because it’s very closely associated with general “dementia”.
Latest Answers