Infant cognitive development

The cognitive development of infants is the part of developmental psychology that studies the internal mental states of infants and very young children. How infants begin to think, remember and process information is valuable knowledge to many disciplines, and remains largely unknown due to experimental challenges, philosophical questions (see nativism), and infant amnesia.

With its origin in the first half of the 20th century, an early and influential theory in this field is Jean Piaget's Theory of cognitive development. Since Piaget's contribution to the field, infant cognitive development and methods for its investigation have advanced considerably —for example, see Neo-Piagetian theories of cognitive development.

Overview
Tabula rasa is a theory that the (human) mind is at birth a "blank slate" without any rules for processing data, that data is added and rules for processing are formed solely by one's sensory experiences. The modern idea of the theory is mostly attributed to John Locke's An Essay Concerning Human Understanding, written in the 17th century.

Its corollary, nativism, argues that we are born with certain cognitive modules that allow us to learn and acquire certain skills, such as language, and is most associated with the recent work of Noam Chomsky, Jerry Fodor, and Steven Pinker.

If one accepts that nothing is known until learned, and that everyone shares a basic common sense, it appears infants must—to some degree—make some specific ontological inferences about how the world works, and what kinds of things it contains. This procedure is studied in psychology and its validity is studied in philosophy.

Piaget
According to Jean Piaget's theory of development there are four stages of cognitive development. The first stage is the Sensorimotor Stage, which starts at birth and extends until the infant is about 2 years of age. During this stage infants gain knowledge through actions that allow them to directly experience and manipulate objects around them. They also gain practical knowledge about the effects of their actions, such as grasping or pushing objects. A major mile stone in this stage is object permanence, which occurs at the end of the stage, where the infant realizes that just because they can't see an object it does not mean that it does not exist.

The second stage is called the "Preoperational Stage" and appears between birth and two years old. In this stage children are just beginning to develop their thinking skills and can use words, symbols and images to represent the world.

The third stage starts at about the age of 7. This is called the Concrete Operational Stage. This is where the child becomes logical, but is only tied to concrete activities and tasks, meaning they can produce relationships and think in a sequence.

Then when the child enters adolescence, they move on to the final stage, called the "Formal Operational Stage". This is where the child can think abstractly—understanding algebra, for example.

Causality rules
Babies less than a year old can distinguish causal events from non-causal ones that have similar spatio-temporal properties. When one solid object appears to pass through another, infants are surprised. They distinguish objects that move only when acted upon from ones that are capable of self-generated motion (the inanimate/animate distinction).

Infant relationships and behavior toward other people
They assume that the self-propelled movement of animate objects is caused by invisible internal states—of goals and intentions—whose presence must be inferred, since internal states cannot be seen.

Physical Laws
Largely thanks to the innovative strategies developed by Renee Baillargeon and her colleagues, considerable knowledge has been gained in the last 25 years about how young infants come to understand natural physical laws. Much of this research depends on carefully observing when infants react as if events are unexpected. For example, if an infant sees an object that appears to be suspended in mid-air, and behaves as if this is unexpected, then this suggests that the infant has an understanding that things usually fall if they are not supported. Baillargeon and her colleagues have contributed evidence, for example, about infants’ understanding of object permanence and their reasoning about hidden objects.

Symbolic Thought
Symbolic thought refers to the ability to use words, images, and other symbols to represent words or feelings. During the preoperational stage a child's capacity for symbolism increases, this is shown by their increase in language use during this stage. This can also be seen by the way children play with objects, a stick becomes a sword and a box becomes armor. Children in this stage still might not understand that a map represents a real place, and that a picture of food does not have a smell.

Self-awareness
Self-awareness is widely believed among psychologists to typically develop at about the age of one. Self-awareness is the realization that one's body, mind, and actions are separate from those of other people. Tests performed for self-consciousness include applying a dot on a subject's nose, and then placing them in front of a mirror—if they start to investigate the dot and touch their nose, it appears that they may realize their own existence in a self-aware sense. Most other species will assume that the animal in the mirror is another animal.

Object permanence
Object permanence is the understanding that an object continues to exist, even when one cannot see it or touch it. It is an important milestone in the stages of cognitive development for infants. Numerous tests regarding it have been done, usually involving a toy and a crude barrier which is placed in front of the toy, and then removed repeatedly (peekaboo). In early sensorimotor stages, the infant is completely unable to comprehend object permanence. Psychologist Jean Piaget conducted experiments with infants which led him to conclude that this awareness was typically achieved at eight to nine months of age. Infants before this age are too young to understand object permanence, which explains why infants at this age do not cry when their mothers are gone – "Out of sight, out of mind". A lack of object permanence can lead to A-not-B errors, where children look for an object at the location where they first discovered it rather than where they have just seen it placed.

Studies in recent psychology also suggest that three dimensionality is not intuitive, and must be learned in infancy using an unconscious inference. (see depth perception)