 In explaining the behavior of nonlinguistic and prelinguistic creatures cognitive ethologists and developmental psychologists often appeal to representational states. Spelke, for example, attempts to explain the development of the ability to perceptually organize the visual array into unitary, persisting objects by appeal to an infant’s capacity to form a representation of the visual surface layout and the presence of mechanisms following basic principles of cohesion, boundedness, rigidity, and no action at a distance (Spelke 1990). These capacities are claimed to explain the infant’s rudimentary physical reasoning, underlying, for example, its ability to track the motion of particular objects and exhibit certain expectancy responses regarding the persistence of objects behind occlusions (as exhibited, for example, in Baillargeon’s (1987) famous drawbridge experiment, in which an infant is habituated to see a screen rotate 180°, and is dishabituated when the screen ‘passes through’ an object placed behind it. The dishabituation reflects the infant’s expectation that the screen’s rotation will be blocked by the occluded object). Such research suggests that an explanation of the infant’s behavior should appeal to the way the infant is perceptually aware of the world, as segmented into objects that exhibit certain predictable regularities.