How Does Cognition Develop in Infancy?
The initial section of the chapter investigates how cognition develops in infancy. Researchers and theorists have long wondered how much our genetic inheritance influences cognitive development (nature) and how much is attributable to the environment (nurture). This clash between heredity and the environment has long been termed the nature–nurture debate. Recent discoveries from behavioral neuroscience suggest that we have more innate abilities than was previously believed. Infants come into the world with a number of basic reflexes, including the orienting reflex, rooting reflex, and grasping reflex. The process of brain myelination increases the speed at which the neurons are able to transmit signals and sets the stage for early learning. This brain maturation is likely highly correlated with the different stages of development and their characteristics. Research using the preferential looking technique has given us new information on the development of skills in infants, such as visual acuity, depth perception, and auditory perception. The final part of the section presents Piaget's theory of cognitive development and the stages at which critical cognitive skills are developed. While recent research has challenged the ages at which these abilities are acquired, Piaget's ideas have had tremendous influence on our understanding of child development.

Table 11.1: Piaget's Stages of Development
Stage	Critical Cognitive Tasks
Sensorimotor (0–2 years)	object permanence
Preoperational (2–7 years)	conservation of quantity
Concrete operational (7–12 years)	concrete logic
Formal operational (12+ years)	hypothetic–deductive reasoning

Does Object Knowledge Develop in Infancy or Is It Innate?
In the next section, the authors continue to weigh the nature–nurture debate through the development of object knowledge in infants. Recent research indicates that perception, action, and reasoning are built-in abilities that develop together over time. Again, it is likely that brain maturation allows the exhibition of inborn skills via interaction with the environment. Data from psychological science support the contention that infants have innate knowledge about physics, math, and reasoning/problem solving. David Premack addressed an additional cognitive skill that he termed theory of mind. This refers to the unique human ability to explain and predict behavior in terms of mental states. It appears that all of these skills develop independently and are enhanced by exposure to the world and formal instruction.

Do Children Have Good Memory Systems?
The next section provides an overview of the development of children's memories. For years, investigators accepted the Freudian notion of infantile amnesia. That is, since adults are unable to remember events before the age of three, then children must be unable to form memories before that time. Recent advances in experimental techniques have revealed that some rudimentary forms of memory are evident as early as 18 months. However, young children still are easily confused as to the source of their knowledge (source amnesia). They also are easily manipulated by repeated, suggestive questioning. All of these memory characteristics seem to be related to the development of the frontal lobes, which do not fully mature until adolescence or later.

How Does Language Develop?
Research on the acquisition of language is another area in which it seems that many developmental functions are innate. While it appears that we are responding to the environment in a trial-and-error fashion, we actually are preprogrammed to display speech in a specified progression through grunts, cooing, babbling, first words, and telegraphic speech. This same progression is seen across cultures and languages. However, information gained from language-deprived individuals does make it evident that there is a sensitive period during which we need environmental input for normal language to develop. This also has implications for learning a foreign language, as evidence suggests that your chances for fluency are increased with earlier exposure. Research also indicates that we are innately programmed to learn the grammar of a language. It is astonishing how quickly children pick up the complexities of the phonology, morphology, and syntax of their native tongue. Even children who grow up in a multilingual culture and mix the existing languages into a new one (creole) will then impose universal grammar rules on the new language.

How Does Cognition Change after Childhood?
The final section of the chapter addresses the issue of cognitive development with an overview of the research on changes that occur after childhood. It is apparent that adolescence marks the beginning of one's ability to reason abstractly about the environment and the future as well as to think about one's own thoughts (metacognition). The changes in cognitive functions that occur in the elderly provide perplexing obstacles to our understanding of development. Aging is commonly associated with a slowing of mental processing speed and difficulty with short-term memory tasks involving multiple pieces of information or divided attention. Fortunately, relatively few people exhibit the dementia or major memory loss that stereotypes the elderly. Many maintain or enhance the knowledge associated with crystallized intelligence, particularly if they remain mentally active.