The 35-year-old singer used to have platinum blonde hair and though she got used to being treated ''differently'' with her striking look, she was still surprised when she was approached by a group of youngsters who thought she was the 'Poker Face' hitmaker.
She said: ''Ages ago, I was at the zoo in Omaha, Nebraska, back when I had platinum hair.
''When I had that hair, it was something else. I got treated differently, sometimes better, sometimes worse.
''Kids were kind of eyeing us. I thought, 'Maybe they're coming to the show tonight...' and they came up and asked me if I was Lady Gaga and if they could get their picture taken with me.''
The 'Digital Witness' singer no longer uses social media apps on her phone because they made her so ''bummed'' about what's going on in the world.
Asked when she last had a row on social media, she explained to Q magazine: ''I took Twitter and stuff off my phone, just because I was getting so bummed out about the state of the world.
''But it was a while ago, around the Trump inauguration. Tensions were high and he had a white child band play 'When the Saints Go Marching In', which seemed really racially inconsiderate - shocker for Trump - but then also, they were s***ty.
''I posted something about it and I got people accusing me of trying to crush the dreams of children.''
St. Vincent - whose real name is Annie Clark - admitted it's unusual for her to hit back.
She continued: ''I was like, 'This has nothing to do with the children!' It's one of the few times I actually ever even responded.
''I'd never throw children under the bus, it's not about that.''