limoges@ac.dal.ca (02/11/91)
I recall from a physiology course I took a number of years ago that the human eye can 'see' 20 frames per second. That is to say that the latency of a picture on the retina is approximately one twentieth of a second, such that movies projected at 24 frames per second (used to be standard for 8mm movies, the film, not the video kind) seem smooth, while at 16 the action seems to be jumpy. Also this latency is what is exploited by the many magicians that specialize in slight of hand tricks; just execute the trick fast enough that the eye has no time to 'see' the action. Hope this is to your satisfaction, Bertrand Limoges
lfk@eastman1.mit.edu (Lee F. Kolakowski) (02/12/91)
On 7 Feb 91 15:53:41 GMT, d90-ngp@sm.luth.se (Niklas Grip) said: > Can anyone tell me how many "pictures/second" a human can see, and if > that's much compared to other animals? The eye does not work like a camera. It has no shutter. Each of the photorecepor cells receives light independently of each other photoreceptor. Now the processed images take on the order of 100 msecs to create. That is measured by presenting subjects with images for different lengths of time and then querying about the content. The speed of the human eye as compared to other animals eyes as a result of the measurement technique cannot be measured the same way. Most vertebrate photoreceptor biochemistry works on the some time scale because the process is virtually the same. 1) Rhodopsin(11-cis) + hv --> Rhodopsin(all-trans) 2) Rhodopsin(all-trans) + Gprotein(GDP) --> Rhodopsin(all-trans)-Gprotein(GTP) 3) Gprotein(GTP) + PDE(inactive) --> Gprotein(GTP)-PDE(active) 4) PDE(active) + cGMP --> PDE(active) + GMP 5) as cGMP levels drop, a cGMP sensitive channel closes This is a simple version of the signal that the brain sees. from fruit flys to fish to frogs to cows to humans the rhodopsin is largely similar -- Frank Kolakowski ======================================================================= |lfk@athena.mit.edu or lfk@eastman1.mit.edu or kolakowski@wccf.mit.edu| | Lee F. Kolakowski M.I.T. | | Dept of Chemistry Room 18-506 | | 77 Massachusetts Ave. Cambridge, MA 02139 | | AT&T: 1-617-253-1866 #include <disclaimer.h> | ======================================================================= ||Desert Storm - Lasers have made this the cleanest *dirty war* ever.|| =======================================================================
jgk@osc.COM (Joe Keane) (02/13/91)
There is an experiment which determines this. You shine a light of given intensity for some interval and have a subject determine the subjective brightness. For a long interval this depends only on the intensity, while for a short interval it depends on the intensity integrated over time. By graphing this you can determine the `integrating time' of the eye. I don't have an exact number, but i remember it being around 50 ms.