 Spatiotemporal continuity of objects. As adults, we know that objects are spatiotemporally continuous; an object that appears at point \(A\) and then at point \(B\) must have traversed a continuous path between these points. Here too the violation of expectancy looking time paradigm has been used to test the Empiricist claim that such knowledge requires an extended learning period. In one study (Spelke et al. 1995), 4.5-month-olds were shown a stage with 2 screens on it, with a visible gap between the screens. In the discontinuous motion condition, each screen has an object hidden behind it. First, the object behind the left screen is moved further left so that the baby sees it, then it is moved back behind that same screen. The object behind the right screen is shown in the same way, so that during these displays only one object has been visible at a time and no object has ever been shown to cross the gap between the two screens. Adults seeing this display infer that there are 2 objects involved. To find out if babies make the same inference, the screens are removed and the infant is shown either one object or two objects. The result is that infants look longer at the one-object display, presumably expecting, like adults, that there had to be two objects; otherwise, the object would have been visible crossing the gap. In a follow-up study, a continuous motion condition was used. This condition is identical to the previous condition except that, between the alternating trials, an object is seen crossing the gap. In this condition babies looked longer at the display of two objects. Like adults, they presumably assumed there was a single object moving back and forth (Aguiar &amp; Baillargeon 1999 report similar findings with 2-month-olds).  Generally, by 2-months, and perhaps earlier, infants expect that objects persist through time, move continuously, have parts that cohere, and are solid (Spelke 1990).  Recent work (Rips &amp; Hespos 2015) shows that by 6-months, babies already have different expectations for rigid bodies, soft objects, and liquids.