"For a long time I assumed that everybody had a colour for each day of the week or for all of their friends' names."
She also said the condition affects her when she makes music, saying music and images went hand in hand for her.
"You pick a chord then all of a sudden there's this flood of a different colour or a different texture. It's exciting and it's strange and it makes everything feel a little bit more vivid," she said.
"There are definitely moments when I just want to listen instead of seeing everything because there are definitely sounds which are overwhelmingly visual with texture and colour. It's like, 'Ah, it's too much!'"
In a separate video, Lorde said dancing on top of a car in the video for Green Light was one of the "strangest things I've done".
"It was quite difficult to dance on the roof of a Suburban at three in the morning. Cars are generally not built to have a girl dancing around losing her mind on top of them."
Lorde is building up to the release of her new album Melodrama on June 16.
