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

The Mind's Eye 281DHD K h3The shapes were symmetrical or nearly symmetrical, or always had thesame kinds of frills on each side, so people would never have to describethe parts' up-down and side-to-side arrangements in the same referenceframe. With these shapes, people were uniformly quick at identifying themin all their orientations; upside down was no slower than right-side up.So people use all the tricks. If a shape's sides are not too different, theystore it as a 3-D geon model centered on the object's own axes. If the shapeis more complicated, they store a copy of what it looks like at each orientationthey see it in. When the shape appears at an unfamiliar orientation, theymentally rotate it into the nearest familiar one. Perhaps we shouldn't be surprised.Shape recognition is such a hard problem that a single, general-purposealgorithm may not work for every shape under every viewing condition.Let me finish the story with my happiest moment as an experimenter.You may be skeptical about the mental turntable. All we know is thattilted shapes are recognized more slowly. I've glibly written that peoplerotate an image, but maybe tilted shapes are just harder to analyze forother reasons. Is there any evidence that people actually simulate a physicalrotation in real time, degree by degree? Does their behavior showsome signature of the geometry of rotation that could convince us thatthey play a movie in their minds?Tarr and I had been baffled by one of our findings. In a differentexperiment, we had tested people both on the shapes they had studiedand on their mirror images, at a variety of orientations:What people were taughtStandard:©*"Mirror: