Psychedelic Scene from Charly

In middle school, I read a short story called "Flowers for Algernon" by Daniel Keyes, about a mentally challenged man who undergoes a surgical procedure to become a genius. In 1967, it was adapted for the big screen under the title "Charly". As with most adaptions, a number of changes were made, but the most apparent one is the inclusion of the psychedelic scene below. It has no equivalent scene in the original story, so it would seem it's inclusion was merely a way for the filmmakers to take advantage of the countercultural zeitgeist.

The rest of the film is available on Youtube, so you can see how abrupt and out-of-place the scene feels compared to the rest of the movie.