Steven Pinker -- How the Mind Works - Hampshire High Italian ...

140 HOW THE MIND WORKSThe advantages of intermediate-level awareness are not hard to find.Our perception of a constant shape and lightness across changes inviewing conditions tracks the object's inherent properties: the lump ofcoal itself stays rigid and black as we move around it or raise the lights,and we experience it as looking the same. The lower levels are notneeded, and the higher levels are not enough. The raw data and computationalsteps behind these constancies are sealed off from our awareness,no doubt because they use the eternal laws of optics and neitherneed advice from, nor have any insights to offer to, the rest of cognition.The products of the computation are released for general consumptionwell before the identities of objects are established, because we needmore than a terse mise en scene to make our way around the world.Behavior is a game of inches, and the geometry and composition of surfacesmust be available to the decision processes that plan the next stepor grasp. Similarly, while we are understanding a sentence there is nothingto be gained in peering all the way down to the hisses and hums ofthe sound wave; they have to be decoded into syllables before theymatch up with anything meaningful in the mental dictionary. Thespeech decoder uses a special key with lifelong validity and should beleft to do its job without interference from kibbitzers in the rest of themind. But as with vision, the rest of the mind cannot be satisfied withonly the final product, either—in this case the speaker's gist. Thechoice of words and the tone of voice carry information that allows us tohear between the lines.The next noteworthy feature of conscious access is the spotlight ofattention. It serves as the quintessential demonstration that unconsciousparallel processing (in which many inputs are processed at the sametime, each by its own mini-processor) can go only so far. An early stage ofparallel processing does what it can, and passes along a representationfrom which a more cramped and plodding processor must select theinformation it needs. The psychologist Anne Treisman thought up a fewsimple, now classic demonstrations of where unconscious processingleaves off and conscious processing begins. People are shown a display ofcolored shapes, like X's and O's, and are asked to press a button if theysee a specified target. If the search target is an O and the display showsone O in a sea of X's, the person responds quickly. It doesn't matter howmany X's there are; people say the O just pops out. (Pop-out; as theeffect is now called, is a nice sign of unconscious parallel processing.)Similarly, a green O pops out from a sea of red O's. But if the experi-