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

318 I HOW THE MIND WORKSgrapevines and snails may be jagged agglomerations of different materials,but if you pick up one end, the other end comes along for the ride.Kelman and Spelke bored babies with two sticks poking out frombehind the top and bottom edges of a wide screen. The question waswhether the babies would see the sticks as part of a single object. Whenthe screen was removed, the babies saw either one long stick or twoshort ones with a gap between them. If the babies had visualized a singleobject, then seeing a single object would be a bore, and two would comeas a surprise. If they had thought of each piece as its own object, thenseeing a single object would be a surprise, and two a bore. Control experimentsmeasured how long infants looked at one versus two objects withouthaving seen anything beforehand; these baseline times weresubtracted out.Infants might have been expected to see the two pieces as two pieces,or, if they had mentally united them at all, to have used all the correlationsamong the features of an object as criteria: smooth silhouettes,common colors, common textures, and common motions. But apparentlyinfants have an idea of objecthood early in life, and it is the core of theadult concept: parts moving together. When two sticks peeking out frombehind the screen moved back and forth in tandem, babies saw them asa single object and were surprised if the raised screen revealed two.When they didn't move, babies did not expect them to be a single object,even though the visible pieces had the same color and texture. When astick peeked out from behind the top edge and a red jagged polygonpeeked out from behind the bottom edge, and they moved back andforth in tandem, babies expected them to be connected, even thoughthey had nothing in common but motion.The child is parent to the adult in other principles of intuitivephysics. One is that an object cannot pass through another object like aghost. Renee Baillargeon has shown that four-month-old infants are surprisedwhen a panel just in front of a cube somehow manages to fall backflat to the ground, right through the space that the cube should be occupying.Spelke and company have shown that infants don't expect anobject to pass through a barrier or through a gap that is narrower than theobject is.A second principle is that objects move along continuous trajectories:they cannot disappear from one place and materialize in another, as inthe transporter room of the Enterprise. When an infant sees an objectpass behind the left edge of a left screen and then seem to reappear from