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

292 HOW THE MIND WORKSthan neatly factoring them into separate assertions. Mental rotation is agood example. In assessing an object's shape, a person cannot ignore itsorientation—which would be a simple matter if orientation weresequestered in its own statement. Instead, the person must nudge theorientation gradually and watch as the shape changes. The orientation isnot re-computed in one step like a matrix multiplication in a digitalcomputer; the farther a shape is dialed, the longer the dialings takes.There must be a rotator network overlaid on the array that shifts thecontents of cells a few degrees around its center. Larger rotationsrequire iterating the rotator, bucket-brigade style. Experiments on howpeople solve spatial problems have uncovered a well-stocked mentaltoolbox of graphic operations, such as zooming, shrinking, panning,scanning, tracing, and coloring. Visual thinking, such as judgingwhether two objects lie along the same line or whether two blobs of differentsizes have the same shape, strings these operations into mentalanimation sequences.Finally, images capture the geometry of an object, not just its meaning.The surefire way of getting people to experience imagery is to askthem about obscure details of an object's shape or coloring—the beagle'sears, the curves in the B, the shade of frozen peas. When a feature isnoteworthy—cats have claws, bees have stingers—we file it away as anexplicit statement in our conceptual database, available later for instantlookup. But when it is not, we call up a memory of the appearance of theobject and run our shape analyzers over the image. Checking for previouslyunnoticed geometric properties of absent objects is one of themain functions of imagery, and Kosslyn has shown that this mentalprocess differs from dredging up explicit facts. When he asked peoplequestions about well-rehearsed facts, like whether a cat has claws or alobster has a tail, the speed of the answer depended on how strongly theobject and its part were associated in memory. People must haveretrieved the answer from a mental database. But when the questionswere more unusual, like whether a cat has a head or a lobster has amouth, and people consulted a mental image, the speed of the answerdepended on the size of the part; smaller parts were slower to verify.Since size and shape are mixed together in an image, smaller shapedetails are harder to resolve.For decades, philosophers have suggested that the perfect test ofwhether mental images are depictions or descriptions was whether peoplecan reinterpret ambiguous shapes, like the duck-rabbit: