It turns out that a shy person can act like someone else more easily than he can act like himself. That makes some sense because shyness is caused by an internal feeling that you are not worthy to be in the conversation. Acting like someone else gets you out of that way of thinking.

Because they never received disability accommodations or any understanding of themselves as members of an oppressed group, many masked Autistics cope by hiding behind a façade of neurotypicality.

PTSD-fueled hypervigilance can look a lot like masking: you’re constantly scanning your environment for threats, and modulating how you present yourself, so you can stay safe. To complicate matters, many Autistic people experience trauma at a young age, and have PTSD symptoms from that.