Editing Naïve physics (section)

===Types of experiments===
The basic experimental procedure of a study on naïve physics involves three steps: prediction of the infant's expectation, violation of that expectation, and measurement of the results. As mentioned above, the physically impossible event holds the infant's attention longer, indicating surprise when expectations are violated.<ref name="goswami"/>

====Solidity====
An experiment that tests an infant's knowledge of solidity involves the impossible event of one solid object passing through another. First, the infant is shown a flat, solid square moving from 0° to 180° in an arch formation. Next, a solid block is placed in the path of the screen, preventing it from completing its full range of motion. The infant habituates to this event, as it is what anyone would expect. Then, the experimenter creates the impossible event, and the solid screen passes through the solid block. The infant is confused by the event and attends longer than in probable event trial.<ref>{{cite journal | last1 = Baillargeon | first1 = R. | author-link = Renee Baillargeon | year = 1994 | title = How Do Infants Learn About the Physical World? | journal = [[Current Directions in Psychological Science]] | volume = 3 | issue = 5| pages = 133–140 | doi=10.1111/1467-8721.ep10770614| s2cid = 144988926 }}</ref>

====Occlusion====
An occlusion event tests the knowledge that an object exists even if it is not immediately visible. [[Jean Piaget]] originally called this concept [[object permanence]]. When Piaget formed [[Piaget's theory of cognitive development|his developmental theory]] in the 1950s, he claimed that object permanence is learned, not innate. The children's game [[Peekaboo|peek-a-boo]] is a classic example of this phenomenon, and one which obscures the true grasp infants have on permanence. To disprove this notion, an experimenter designs an impossible occlusion event. The infant is shown a block and a transparent screen. The infant habituates, then a solid panel is placed in front of the objects to block them from view. When the panel is removed, the block is gone, but the screen remains. The infant is confused because the block has disappeared indicating that they understand that objects maintain location in space and do not simply disappear.<ref>{{cite journal | last1 = Baillargeon | first1 = R | year = 2004 | title = Infants' Physical World | journal = Current Directions in Psychological Science | volume = 13 | issue = 3| pages = 89–94 | doi=10.1111/j.0963-7214.2004.00281.x| s2cid = 5634093 }}</ref>

====Containment====
A containment event tests the infant's recognition that an object that is bigger than a container cannot fit completely into that container. [[Elizabeth Spelke]], one of the psychologists who founded the naïve physics movement, identified the continuity principle, which conveys an understanding that objects exist continuously in time and space.<ref name="goswami"/> Both occlusion and containment experiments hinge on the continuity principle. In the experiment, the infant is shown a tall cylinder and a tall cylindrical container. The experimenter demonstrates that the tall cylinder fits into the tall container, and the infant is bored by the expected physical outcome. The experimenter then places the tall cylinder completely into a much shorter cylindrical container, and the impossible event confuses the infant. Extended attention demonstrates the infant's understanding that containers cannot hold objects that exceed them in height.<ref>{{cite journal | last1 = Baillargeon | first1 = R. | last2 = Hespos | first2 = S.J. | year = 2001 | title = Infant's Knowledge About Occlusion and Containment Events: A Surprising Discrepancy | journal = [[Psychological Science]] | volume = 12 | issue = 2| pages = 141–147 | doi = 10.1111/1467-9280.00324 | pmid = 11340923 | s2cid = 1766183 }}</ref>