[mezzie2]

ASL (and sign language generally) and tactile sign are two different languages, and language types that are at least as different as verbal languages and seen/sign languages - an American deafblind person who uses tactile sign and meets someone who uses ASL isn't necessarily going to be able to communicate with them. The signs and underlying language structure (morphology/syntax/etc.) are all different. I wouldn't consider the existence of tactile sign to mean that sign language works in the dark because they're two different language types, but the terminology is confusing and I have a linguistics background so I don't know if the author was including tactile sign or not. I'd guess not since it's about teaching his daughter who is d/Deaf, not deafblind, and tactile sign isn't in much use outside of the deafblind community. d/Deaf and blind people don't use it much, I believe.

[adinisom]

They can definitely be distinct languages as is the case with protactile. For the deaf-blind people I've met, ASL is their first language and protactile is more of a second. Maybe it's different in other areas of the world.

What I've noticed is that in deaf-blind contexts plain ASL is terrible for back-channeling information... is the listener paying attention? Agreeing? Disagreeing? Laughing? Protactile communicates these back to the signer using touch, and not touching is considered rude.