Schizophrenia produces many symptoms other than hallucinations and causes profound cognitive and social dysfunction. Poverty of thought, delusions, and disordered thinking and speech among others. There would be signs others could see.

The sighted schizophrenics don't know their hallucinations aren't real. It's always an external diagnosis.

dude they're blind, not stupid.

1. If you know you're alone at home and then hear voices, that might be one way. There are ways to distinguish the presence of people beyond sight.

2. Blindness is much more than total blindness, which only describes a minority of blind people. There are different definitions, but the World Health Organization puts the definition as less than 3/60 or a visual field of less than 10 degrees in the better-seeing eye. That basically means that if you need to be more than 20 times closer to an object to be able to see the same level of detail, or you have almost no peripheral vision, you qualify.

Well, asking someone else who is around would be a good way, for one thing.