No. Lag of accommodation refers to the fact that human eye doesn't accommodate enough on objects which are too close and accommodates too much on objects which are far. At some intermediate distance (called the resting point of accommodation, about 80cm to 1.5m), the eye accommodates accurately
a) Eye lens has so much chromatic aberration (and substantial spherical abberation) that focusing to produce a "sharp image" is literally meaningless (exactly as LeGrand said).
Hi Henning,I'd imagine that probably, experiments with pictures shown only for very short amounts of time have been conducted to give a better impression of what the eye really can extract from a single picture instantaneously.
Chimpanzees are much better than humans at that:
Absolutely, there's certainly no reason to consider the human visual capacity to be anything outstanding!
An engineer would have designed the bird's eye. The engineer who designed the human eye would have been fired ;-)
After a coffee break, we started Part II of the talk where the eye was seen in a very different light...
Cool presentation, thanks a lot for sharing! My favourite is the angular diagram on "Human visual attention". I suppose "text" means that one is able to read text within a centered 20° cone?
Presumably the part of the brain responsible for the application of colours to a scene we view does this by responding to the frequencies of the light in order to select an appropriate colour from (another presumption) a 'database' of colours built into our brains by our homo sapiens DNA.Thank you and sorry for late reply.
Yes, that's what it means. The sharp field of view of human vision is only 0.5 to 1 degree wide depending how strictly you define sharpness. This means, in your typical binoculars with 60-degree apparent field of view, only 1/3600 of the visible area is seen sharply at any given time!! The entire field of view is perceived via a series of scans whose exact order we don't remember consciously. The Russian scientist Alfred Yarbus has made numerous studies of human eye movements when examining a scene.
The "unsharp" part of human's field of view is used for proprioception (figuring out where we are in the world) and detection of movement (both self-movement and movement of other objects).
A most astonishing fact: In humans and other primates, the visual information is branched into 6 parallel pathways after going through the Lateral Geniculate Nucleus (LGN). Four of these pathways carry color information while the other two carry only luminance information. Perspective, stereoscopic vision, form and movement are processed by the pathway which is not color selective!
One part of the brain works only in black-and-white and creates line-drawings of the visual world. Another part of the brain paints these line drawings if time permits!
See Margaret Livingstone and David Hubel, Segregation of Form, Color, Movement, and Depth: Anatomy, Physiology, and Perception, Science, Vol. 240, May 1988 (Dr. Hubel won the Nobel Prize for his work on eye physiology in 1981. He has passed away. His student, Dr. Livingstone, deserve to win one as well.)
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