问答题 Tets of reaction times also seemed to back up the notion that the two hemispheres differed in their processing styles. A trick researchers use to ensure that an image goes to one hemisphere first, and then to the opposite side of the brain. (46) If the nature of the stimulus and the preference of the hemisphere match up, then the person can respond slightly more quickly and accurately in identifying the local or global letter.
Still more startling, researchers found that the same appears to hold for the brains of chimps (黑猩猩) and perhaps other primates (灵长类). (47) The assumption has always been that handedness and brain asymmetry are strictly human traits—part of the great brain reorganization that allowed our ancestor to use tools, speak and perhaps even think rationally. But handedness is now widely claimed for primates and even birds, amphibians (两栖动物) and whales, and in the past few years, some psychologists have Tested chimps and baboons (狒狒) and suggested their two hemispheres also differ in processing style.
(48) Now researchers have come to see the distinction between the two hemispheres as a subtle one of processing style, with every mental faculty shared across the brain, and each side contributing in a complementary, not exclusive, fashion. A smart brain became one that simultaneously grasped both the foreground and the background of the moment.
The next problem was to work out exactly how the brain manages to product these two contrasting styles. Many researchers originally looked for the explanation in a simple wiring difference within the brain. This theory held that neurons (神经元) in the left cortex (脑皮质) might make sparser (稀少的), short-range connections with their neighbors, with cells on the other side would be more richly and widely connected. (49) The result would be that the representation of sensations and memories would be confined to smallish, discrete (离散的) areas in the left hemisphere, while exactly the same input to a corresponding area of the right side would form a sprawling even impressionistic, pattern of activity. Supporters of this idea argued that these structural differences would explain why left brain language areas are so good at precise resonation of words and word sequences while the right-brain seems to supply a wider sense of contest and meaning. A striking finding from some people who suffer right brain strokes is that they can understand the literal meaning of sentences—their left brain can still decode the words—but they can no longer get jokes or allusions. (50) Asked to explain even a common proverb, such as "a stitch in time saves nine", they can only say it must have something to do with sewing—an intact right brain is needed to make the more playful connections.