Although not truly the point... we do know that people don't seen red and green flipped because color's don't work in isolation. It's also how they work together. If a person with flipped red/green mixed what they saw as red (actually green) with blue, they wouldn't get purple.
We could suppose that someone could see the entire spectrum inverted, but that causes other problems that we could test for. There are more hues between red and blue than there are between green and yellow. Instead of seeing brown (really dark yellow), they'd see dark blue.
We could suppose that someone could see the entire spectrum inverted, but that causes other problems that we could test for. There are more hues between red and blue than there are between green and yellow. Instead of seeing brown (really dark yellow), they'd see dark blue.