Recent findings suggest that visual signals are fedinto at least three separate processing systems inthe brain, each with its own distinct function. Onesystem appears, to process information about shapeperception; a second, information about color; athird, information about movement, location, andspatial organization. An understanding of thefunctions and capabilities of these three systems canshed light on how artists manipulate materials to create surprising visual effects.
It is possible to summarize the functions of the three subsystems of the visual system asfollows. The parvo system carries highly detailed information about stationary objects andabout borders that are formed by contrasting colors. It does not, however, carry informationabout specific colors. Because much of the information about the shape of objects can berepresented by their borders, we suspect that this system is important in shape perception. The blob system processes information about colors, but not about movement, shapediscrimination, or depth. The magno system carries information about movement and depth. It is good at detecting motion but poor at scru-tinizing stationary images. In addition itappears to be colorblind; it is unable to perceive borders that are visible only on the basis ofcolor contrast.
Cells in parvo system can distinguish between two colors at any relative brightness of the two. Cells in the color-blind magno system. on the other hand, are analogous to a black-and-whitephotograph in the way they function: they signal information about the brightness of surfacesbut not about their colors. For any pair of colors there is a particular bright-ness ratio at whichtwo colors, for example red and green, will appear as the same shade of gray in a black-and-white photograph, hence any border between them will vanish. Similarly at some relative red-to-green bright- ness level, the red and green will appear identical to the magno system. Thered and green are then called equi-luminant. A border between two equi-luminant colors hascolor contrast but no luminance contrast.
Many artists have seemed to be empirically aware of these underlying principles and haveused them to maximize particular effects. Some of the peculiar effects of Op Art, forexample, probably arise from color combinations that are strong activators of the parvo systembut are weak stimuli for the magno system. An object that is equiluminant with its backgroundlooks vibrant and unstable. The reason is that the parvo system can signal the object'sshape but the magno system cannot see its borders and therefore cannot signal either themovement or the position of the object. Hence it seems to jump around, drift, or vibrate onthe canvas.
The passage is primarily concerned with
A.describing subsystems of the visual system and showing their relevance to art
B.comparing three theories on how the visual system analyzes images in a work of art
C.explaining how artists use color contrasts to create particular visual effects
D.explaining how the visual system distinguishes among different colors
E.describing functions of the first three phases of the visual system
Which of the following would create visual effects most similar to those discussed inlines 43-48?
A.A watercolor in which colors are applied imprecisely to outlined shapes
B.A painting in which different shades of the same color are used to obscure the boundariesbetween objects
C.A black-and-white sketch in which shading is used to convey a sense of depth
D.An advertisement in which key words are at the same level of brightness as a background ofcontrasting color
E.A design in which two different shades of gray are juxtaposed to heighten the contrastbetween them
The passage provides information about which of the following?
A.Why the same system can process information about movement and location
B.Why the parvo system is considered to be responsible for shape perception
C.Why the blob system can process information about colors but not movement
D.The mechanism that enables the blob system to distinguish between stationary objects
E.The mechanism that enables the magno system to carry information about shapediscrimination
According to the passage, which of the following is true of the visual system?
A.It processes visual signals in three consecutive stages.
B.It processes visual signals through separate processing systems in the brain.
C.It consists of only three separate systems.
D.It consists of a single hierarchical system rather than a multipartite system.
E.It consists of separate system with high overlap in processing functions.
The author mentions a “black-and-white photograph” (line 29) most probably inorder to explain
A.how the parvo system distinguishes between different shapes and colors
B.how the magno system uses luminosity to identify borders between objects
C.the mechanism that makes the magno system color-blind
D.why the magno system is capable of perceiving moving images
E.the brightness ratio at which colors become indistinguishable to the parvo system
The author uses all of the following in the discussion in the third paragraph EXCEPT:
B.definition of terms
D.a rhetorical question
The passage suggests which of the following about the magno system?
A.It perceives borders on the basis of luminance contrast.
B.It perceives shapes on the basis of color contrast.
C.It is better at perceiving stationary objects than it is at detecting movement.
D.It can detect motion but it cannot signal the position of an object.
E.It is better at processing information about movement than it is at processing informationabout depth.
正确答案:A D B B B D A
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价格 : ￥1