As one works with color in a practical or experimental way, one is impressed by
two apparently unrelated facts. Color as seen is a mobile changeable thing
depending to a large extent on the relationship of the color to other colors
seen simultaneously. It is not fixed in its relation to the direct stimulus
which creates it. On the other hand, the properties of surfaces that give rise
to color do not seem to change greatly under a wide variety of illumination
colors, usually (but not always) looking much the same in artificial light as in
daylight. Both of these effects seem to be due in large part to the mechanism of
color adaptation mentioned earlier. When the eye is fixed on a
colored area, there is an immediate readjustment of the sensitivity of the eye
to color in and around the area viewed. This readjustment does not immediately
affect the color seen but usually does affect the next area to which the gaze is
shifted. The longer the time of viewing, the higher the intensity, and the
larger the area, the greater the effect will be in terms of its persistence in
the succeeding viewing situation. As indicated by the work of Wright and
Schouten, it appears that, at least for a first approximation, full adaptation
takes place over, a very brief time if the adapting source is moderately bright
and the eye has been in relative darkness just previously. As the stimulus is
allowed to act, however, the effect becomes more persistent in the sense that it
takes the eye longer to regain its sensitivity to lower intensities. The net
result is that, if the eye is so exposed and then the gaze is transferred to an
area of lower intensities, the loss of sensitivity produced by the first area
will still be present and appear as an "afterimage" superimposed on the second.
The effect not only is present over the actual area causing the "local
adaptation" but also spreads with decreasing strength to adjoining areas of the
eye to produce "lateral adaptation" . Also, because of the persistence of the
effect if the eye is shifted around from one object to another, all of which are
at similar brightness or have similar colors, the adaptation will tend to become
uniform over the whole eye.
单选题
The selection is concerned primarily with ______.
A. the eye's adaptation to color
B. the properties of colored surfaces
C. the color of colors
D. the effect of changes in color intensity
【正确答案】
A
【答案解析】[解析] 整篇文章都在讲人眼对光的适应机制。
单选题
Whether a colored object would, no two viewings separated in time,
appear to the view as similar or different in color would depend mostly on
______.
A. the color mechanism of the eye in use at the time of each viewing
B. what kind of viewing had immediately preceded each of the viewings
单选题
If a person's eye has been looking at an object in bright sunlight for
some time, and then shifts to an object not well lit-such as a lawn or shrub in
shadow-we can expect ______.
A. a time lag in the focusing ability of the eye
B. some inability to see colors of the latter-named objects until loss of
sensitivity has been regained
C. the immediate loss of the "afterimage" of the first object
D. adaptation in the central area of the eye but little adaptation in the
lateral areas to the new intensity level