Hack 27. Show Motion Without Anything Moving
2.16.3. In Real Life
The obvious benefit of the phenomenon is that we can sit back and watch television and movies.
It also explains why wheels can look as if they are going backward slowly when they are actually going forward extremely quickly. Remember that apparent motion is strongest when adjacent lights, or images, flash up approximately 50 milliseconds apart. Caught on film, a wheel rotating forward may be turning at such a speed that, after 50 milliseconds (or a frame), it’s made almost a full turn, but not quite. The apparent motion effect is stronger for the wheel moving the short distance backward in that short time rather than all the way round forward, and so it dominates: We see the wheel moving slowly backward, rather than fast and forward.
2.16.4. Hacking The Hack
The phi phenomenon also seems to say something important about the relationship of real time to perceived time. If you show two flashing lights of different colors so as to induce the phi phenomenon, you still get an effect of apparent motion.2 For some people, the light appears to change from the first color to the second as it moves from the first spot (where the first light was shown) to the second spot (where the second light was shown).
Now the thing about this ishow did your brain know what color the light was going to change to? It seems as if what you “saw” (the light changing color) was influenced by something you were about to see. Various theories had been put forward to explain this, either about the revision of our perceptions by what comes after or about the revision of our memories. Philosopher Daniel Dennett3 says that both of these types of theory are misleading because they both imply that conscious experience travels forward in time along a single, one-step-forward-at-a-time-and-no-steps-back track.
Instead, he suggests, there are multiple drafts of what is going on being continuously updated and revised. Within an editorial window (of, some have suggested, about 200 milliseconds of real time), any of these drafts can out-compete the others to become what we experience .4
2.16.5. End Notes
You can measure how the optimum timing of the flashes is affected by distance with the Apparent Motion Experiment maintained by Purdue University’s Visual Perception Online Laboratory (http://www.psych.purdue.edu/~coglab/VisLab/ApparentMotion/AM.html; Java).
You can see a demo of the changing color phi phenomenon here at Ken Kreisman’s Phi Phenomenon Demo page (http://www.cs.tufts.edu/~kreisman/phi/index.html; requires Java).
Dennett, D. C. (1991). Consciousness Explained. Boston: Little, Brown.
Obviously there’s a lot more to both Dennett’s theory and to the philosophy of consciousness in general. “Multiple Drafts: an Eternal Golden Braid?” (http://ase.tufts.edu/cogstud/papers/multdrft.htm) by Daniel Dennett and Marcel Kinsbourn, and this summary of Chapter 5 of Dennett’s book Consciousness Explained, “Multiple Drafts Versus the Cartesian Theater” (http://epmalab.uoregon.edu/writings/Chapter%205%20summary.pdf; PDF), both discuss the mental world as a parallel process that is edited down into a single experience for conscious consumption.
2.16.6. See Also
Greg Egan’s science fiction short story “Mister Volition” (part of the excellent collection Luminous) is inspired by the multiple drafts theory of consciousness and, to understand the theory, a good a place as any to start. See Egan’s bibliography for availability (http://gregegan.customer.netspace.net.au/BIBLIOGRAPHY/Online.html).
Taken From : Mind Hacks
