Quite how the screen *definitely* had a green light and *definitely* had a "C:\" prompt is still a mystery 20 years later!!
No mystery. Users say yes if they think that's the 'right' answer.
Answer to that one is never to put words in their mouths, or ideas in their heads. Instead of 'can you see a green light' ask 'what colour light can you see'. Make *them* describe things to *you*.