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John Ross's experiment with perceiving in depth


The 'persistence of vision' effect
Walter Murch Film-maker
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One of the questions that you eventually wind up asking yourself, that I eventually wind up asking, if you work in film, is: why do we see the illusion of movement in motion pictures, when in fact, it's just a series of still frames? Well, there's a phrase for this, which is 'persistence of vision', or 'the phi effect'. For most people, up to a time, for me certainly up to a certain point, it was like, 'Okay, that's the explanation, that's why it works', and you don't think too hard about it.

And, basically, it's the idea that you see a frame and that frame impresses itself on your retina, kind of like a sealing wax, and then there's a period of darkness when the shutter is closed, and now here's another frame slightly different, and somehow the first frame is still on your retina, this is the vague thinking, fading slowly, and then this new image comes along, and it combines with the first one, and somehow you extract motion out of this. Sometimes the analogy is made with, you know, look at a lightbulb, turn the lightbulb off, look at it, turn it on very quickly and close your eyes, you still see the lightbulb. Somehow this is like something that's going on.

Born in 1943 in New York City, Murch graduated from the University of Southern California's School of Cinema-Television. His career stretches back to 1969 and includes work on Apocalypse Now, The Godfather I, II, and III, American Graffiti, The Conversation, and The English Patient. He has been referred to as 'the most respected film editor and sound designer in modern cinema.' In a career that spans over 40 years, Murch is perhaps best known for his collaborations with Francis Ford Coppola, beginning in 1969 with The Rain People. After working with George Lucas on THX 1138 (1971), which he co-wrote, and American Graffiti (1973), Murch returned to Coppola in 1974 for The Conversation, resulting in his first Academy Award nomination. Murch's pioneering achievements were acknowledged by Coppola in his follow-up film, the 1979 Palme d'Or winner Apocalypse Now, for which Murch was granted, in what is seen as a film-history first, the screen credit 'Sound Designer.' Murch has been nominated for nine Academy Awards and has won three, for best sound on Apocalypse Now (for which he and his collaborators devised the now-standard 5.1 sound format), and achieving an unprecedented double when he won both Best Film Editing and Best Sound for his work on The English Patient. Murch’s contributions to film reconstruction include 2001's Apocalypse Now: Redux and the 1998 re-edit of Orson Welles's Touch of Evil. He is also the director and co-writer of Return to Oz (1985). In 1995, Murch published a book on film editing, In the Blink of an Eye: A Perspective on Film Editing, in which he urges editors to prioritise emotion.

Listeners: Christopher Sykes

Christopher Sykes is an independent documentary producer who has made a number of films about science and scientists for BBC TV, Channel Four, and PBS.

Tags: motion, fly effect, persistence vision, illusion, motion pictures, bulb, retina, cache

Duration: 1 minute, 43 seconds

Date story recorded: April 2016

Date story went live: 29 March 2017