Glimpses are the term for sighting a hidden creature in the Unusual Existence, due to a first experience. It's uncommon, and generally only happens a few times in your life. Do not rely on these to spot, research, and catalog hidden creatures. Rely on other means.
The Vision is an informal term for the ability ERIE syndrome gives.
Not much else is known about how and why these phenomenon have come to be.
Glimpses allow you to see all hidden creatures, as they only change their body in the Usual Existence.