Editing Developmental psychology (section)

===Infant cognition: the Piagetian era===
Piaget suggested that an infant's perception and understanding of the world depended on their motor development, which was required for the infant to link visual, tactile and motor representations of objects.<ref>{{cite journal |last1=Lefmann |first1=Tess |last2=Combs-Orme |first2=Terri |title=Early Brain Development for Social Work Practice: Integrating Neuroscience with Piaget's Theory of Cognitive Development |journal=Journal of Human Behavior in the Social Environment |date=July 2013 |volume=23 |issue=5 |pages=640–647 |doi=10.1080/10911359.2013.775936 }}</ref> The concept of object permanence refers to the knowledge that an object exists even when it is not directly perceived or visible; in other words, something is still there even if it is not visible. This is a crucial developmental milestone for infants, who learn that something is not necessarily lost forever just because it is hidden. When a child displays object permanence, they will look for a toy that is hidden, showing that they are aware that the item is still there even when it is covered by a blanket. Most babies start to exhibit symptoms of object permanence around the age of eight months. According to this theory, infants develop [[object permanence]] through touching and handling objects.<ref name="bremner" />

Piaget's sensorimotor stage comprised six sub-stages (see [[Theory of cognitive development#Sensorimotor stage|sensorimotor stages]] for more detail). In the early stages, development arises out of movements caused by [[primitive reflexes]].<ref name="Gruber">{{Cite book | vauthors = Piaget J |year=1977 |title=The essential Piaget \| veditors = Gruber HE, Voneche JJ |location=New York |publisher=Basic Books |isbn=978-0-7100-8778-2}}</ref> Discovery of new behaviors results from [[classical conditioning|classical]] and [[operant conditioning]], and the formation of [[habit (psychology)|habits]].<ref name="Gruber" /> From eight months the infant is able to uncover a hidden object but will persevere when the object is moved.

Piaget concluded that infants lacked object permanence before 18 months when infants' before this age failed to look for an object where it had last been seen. Instead, infants continued to look for an object where it was first seen, committing the "[[A-not-B error]]". Some researchers have suggested that before the age of 8–9 months, infants' inability to understand object permanence extends to people, which explains why infants at this age do not cry when their mothers are gone ("Out of sight, out of mind").

====Recent findings in infant cognition====
In the 1980s and 1990s, researchers developed new methods of assessing infants' understanding of the world with far more precision and subtlety than Piaget was able to do in his time. Since then, many studies based on these methods suggest that young infants understand far more about the world than first thought.

Based on recent findings, some researchers (such as [[Elizabeth Spelke]] and [[Renee Baillargeon]]) have proposed that an understanding of object permanence is not learned at all, but rather comprises part of the innate cognitive capacities of our species.

According to Jean Piaget's developmental psychology, object permanence, or the awareness that objects exist even when they are no longer visible, was thought to emerge gradually between the ages of 8 and 12 months. However, experts such as Elizabeth Spelke and Renee Baillargeon have questioned this notion. They studied infants' comprehension of object permanence at a young age using novel experimental approaches such as violation-of-expectation paradigms. These findings imply that children as young as 3 to 4 months old may have an innate awareness of object permanence. Baillargeon's "drawbridge" experiment, for example, showed that infants were surprised when they saw occurrences that contradicted object permanence expectations. This proposition has important consequences for our understanding of infant cognition, implying that infants may be born with core cognitive abilities rather than developing them via experience and learning.<ref>{{cite book |doi=10.1093/acprof:oso/9780199692972.003.0002 |chapter=Learning about the mind from evidence |title=Understanding Other Minds |date=2013 |last1=Meltzoff |first1=Andrew N. |last2=Gopnik |first2=Alison |pages=19–34 |isbn=978-0-19-969297-2 }}</ref>

Other research has suggested that young infants in their first six months of life may possess an understanding of numerous aspects of the world around them, including:
* an early [[numerical cognition]], that is, an ability to represent number and even compute the outcomes of addition and subtraction operations;<ref>{{cite journal | vauthors = Wynn K | title = Addition and subtraction by human infants | journal = Nature | volume = 358 | issue = 6389 | pages = 749–750 | date = August 1992 | pmid = 1508269 | doi = 10.1038/358749a0 | bibcode = 1992Natur.358..749W | author-link1 = Karen Wynn }}</ref>
* an ability to infer the goals of people in their environment;<ref>{{cite journal | vauthors = Woodward AL | title = Infants selectively encode the goal object of an actor's reach | journal = Cognition | volume = 69 | issue = 1 | pages = 1–34 | date = November 1998 | pmid = 9871370 | doi = 10.1016/S0010-0277(98)00058-4 }}</ref>
* an ability to engage in simple causal reasoning.<ref>{{cite journal | vauthors = Leslie AM, Keeble S | title = Do six-month-old infants perceive causality? | journal = Cognition | volume = 25 | issue = 3 | pages = 265–288 | date = April 1987 | pmid = 3581732 | doi = 10.1016/S0010-0277(87)80006-9 }}</ref>