Oliver Sacks used drugs to do so:
Sacks recently wrote about his hallucinogenic experiments in a paywalled New Yorker article. Colin Marshall reflects on it:
His desire to conduct these self-experiments flared up in his thirties, when, among other sudden jolts of curiosity, he felt a suspicion that he had never really seen the color indigo. "One sunny Saturday in 1964, I developed a pharmacologic launchpad consisting of a base of amphetamine (for general arousal), LSD (for hallucinogenic intensity), and a touch of cannabis (for a little added delirium). About twenty minutes after taking this, I faced a white wall and exclaimed, ‘I want to see indigo now — now!'"
The Dish 