Developmental psychology is the scientific study of changes that occur in human beings over the course of their life span. Originally concerned with infantsand children, the field has expanded to include adolescence, adult development, aging, and the entire life span. This field examines change across a broad range of topics including motor skills and other psycho-physiological processes; cognitive development involving areas such as problem solving, moral understanding, and conceptual understanding; language acquisition; social, personality, and emotional development; and self-concept and identity formation.
Developmental psychology includes issues such as the extent to which development occurs through the gradual accumulation of knowledge versus stage-like development, or the extent to which children are born with innate mental structures, versus learning through experience. Many researchers are interested in the interaction between personal characteristics, the individual’s behavior, and environmental factors including social context, and their impact on development; others take a more narrowly-focused approach.
Developmental psychology informs several applied fields, including: educational psychology, child psychopathology, and forensic developmental psychology. Developmental psychology complements several other basic research fields in psychology including social psychology, cognitive psychology, ecological psychology, and comparative psychology. Theories Attachment theory Attachment theory, theoretical frame work originally developed by John Bowlby, focuses on open, intimate, emotionally meaningful relationships. Attachment is described as a biological system or powerful survival impulse that evolved to ensure the survival of the infant.
A child who is threatened or stressed will move toward caregivers who create a sense of physical, emotional and psychological safety for the individual. Attachment feeds on body contact and familiarity. Later Mary Ainsworth developed the Strange Situation protocol and the concept of the secure base. There are three types of attachment styles: secure, anxious-avoidant, and anxious-resistant. Secure attachment is a healthy attachment between the infant and the caregiver. It is characterized by trust. Anxious-avoidant is an insecure attachment between an infant and a caregiver.
This is characterized by the infant’s indifference toward the caregiver. Anxious-resistant is an insecure attachment between the infant and the caregiver characterized by distress from the infant when separated and anger when reunited.  A child can be hindered in its natural tendency to form attachments. Some babies are raised without the stimulation and attention of a regular caregiver, or locked away under conditions of abuse or extreme neglect. The possible short-term effects of this deprivation are anger, despair, detachment, and temporary delay in intellectual development.
Long-term effects include increased aggression, clinging behavior, detachment, psychosomatic disorders, and an increased risk of depression as an adult.  Constructivism Constructivism is a paradigm in psychology that characterizes learning as a process of actively constructing knowledge. Individuals create meaning for themselves or make sense of new information by selecting, organizing, and integrating information with other knowledge, often in the content of social interactions. There are two ways in which constructivism can occur: individual and social.
Individual constructivism is when a person constructs knowledge through cognitive processes of their own experiences rather than by memorizing facts provided by others. Social constructivism is when individuals construct knowledge through an interaction between the knowledge they bring to a situation and social or cultural exchanges within that content.  Ecological systems theory The Ecological systems theory, originally formulated by Urie Bronfenbrenner specifies four types of nested environmental systems, with bi-directional influences within and between the systems.
The four systems are microsystem, mesosystem, exosystem, and macrosystem. Each system contains roles, norms and rules that can powerfully shape development. The microsystem is the immediate environment surrounding and influencing the individual (example: school or the home setting). The mesosystem is the combination of two microsystems and how they influence each other (example: sibling relationships at home vs. peer relationships at school). The exosystem is the interaction among two or more settings that are indirectly linked (example: a father’s job requiring more overtime ends up influencing his aughter’s performance in school because he can no longer help with her homework).
The macrosystem is broader taking into account social economic status, culture, beliefs, customs and morals (example: a child from a wealthier family sees a peer from a less wealthy family as inferior for that reason). Lastly, the chronosystem refers to the chronological nature of life events and how they interact and change the individual and their circumstances through transition (example: a mother losing her own mother to illness and no longer having that support in her life).
Since its publication in 1979, Bronfenbrenner’s major statement of this theory, The Ecology of Human Development has had widespread influence on the way psychologists and others approach the study of human beings and their environments. As a result of this conceptualization of development, these environments—from the family to economic and political structures—have come to be viewed as part of the life course from childhood through adulthood.  Psychosexual development Sigmund Freud believed that we all had a conscious, preconscious, and unconscious level.
In the conscious we are aware of our mental process. The preconscious involves information that though we are not currently thinking about can be brought into consciousness. Lastly, the unconscious includes those mental processes which we are unaware of. He believed that the conscious and unconscious had tension because the conscious would try and hold back what the unconscious was trying to express. To explain this he developed three structures of personality; the id, ego, and superego. The id, being the most primitive of the three functioned according to the pleasure principle.
The pleasure principle states that the id’s motivation is to seek pleasure and avoid pain. Based on this he proposed five universal stages of development. The first is the oral stage which occurs from birth to 12 months of age, second is the anal stage which occurs from one to three years of age, third is the phallic stage which occurs from three to five years of age (most of a person’s personality is formed by this age), the fourth is called latency which occurs from age five until puberty, and lastly stage five is the genital stage which takes place from puberty until adulthood. 7]
Stages of moral development Theories of morality that stem from Jean Piaget’s cognitive-developmental viewpoint emphasize shifts in the type of reasoning that individuals use in making moral decisions. Changes in the content of the decision they reach or the actions they take as a result does not occur. [dubious – discuss] Lawrence Kohlberg expanded on this issue specifically during adolescence. He suggested three levels of moral reasoning; preconventional moral reasoning, conventional moral reasoning, and postconventional moral reasoning.
Preconventional moral reasoning is typical of children and is characterized by reasoning that is based on rewards and punishments associated with different courses of action. Conventional moral reason occurs during late childhood and early adolescence and is characterized by reasoning that is based on the rules and conventions of society. Lastly, postconventional moral reasoning is the stage during which society’s rules and conventions are seen as relative and subjective rather than as authoritative.  Stages of psychosocial development Erik Erikson became a child psychoanalyst like his mentor Anna Freud, Sigmond Freud’s daughter.
He went on to reinterpret Freud’s psychosexual stages by incorporating the social aspects of it. He came up with eight stages, each of which has two crisis (a positive and a negative). Stage one is trust versus mistrust, which occurs during infancy. Stage two is autonomy versus shame and doubt which occurs during early childhood. Stage three is initiative versus guilt which occurs during play age. Stage four is industry versus inferiority which occurs during school age. Stage five is identity versus identity diffusion which occurs during adolescence. Stage six is intimacy versus isolation which occurs during young adulthood.
Stage seven is generativity versus self-absorption which occurs during adulthood. Lastly, stage eight is integrity versus despair which occurs during old age. In each of these stages either one or the other crisis is developed. The ideal thing would be to have the positive crisis more developed than the negative crisis.  Theories of cognitive development Jean Piaget was a Swiss theorist who posited that children learn by actively constructing knowledge through hands-on experience. 
He suggested that the adult’s role in helping the child learn was to provide appropriate materials or the child to interact and construct. He would use Socratic questioning to get the children to reflect on what they were doing. He would try to get them to see contradictions in their explanations. He also developed stages of development. His approach can be seen in how the curriculum is sequenced in schools, and in the pedagogy of preschool centers across the United States. Piaget believed that intellectual development took place through a series of stages which caused him to come up with his Theory on Cognitive Development. Each stage consisted of steps which the child had to master before moving on to the next step.
He believe that these stages where not separate from one another but rather each stage built on the previous one, hence learning was continuous. His theory consisted of four stages; sensorimotor, pre-operational, concrete operational, and formal operational. Though he did not believe these stages occurred at any given age, many studies have determine when these cognitive abilities should take place.  Zone of proximal development Lev Vygotsky was a Russian theorist from the Soviet era, who posited that children learn through hands-on experience and social interactions with members of his/her culture. 9]
Unlike Piaget, he claimed that timely and sensitive intervention by adults when a child is on the edge of learning a new task (called the “zone of proximal development”) could help children learn new tasks. Martin Hill stated that “The world of reality does not apply to the mind of a child. ” This technique is called “scaffolding,” because it builds upon knowledge children already have with new knowledge that adults can help the child learn.  Vygotsky was strongly focused on the role of culture in determining the child’s pattern of development, arguing that development moves from the social level to the individual level. 10]
In other words, Vygotsky claimed that psychology should focus on the progress of human consciousness through the relationship of an individual and their environment. He felt that if scholars continued to disregard this connection, then this disregard would inhibit the full comprehension of the human consciousness Nature/nurture A significant issue in developmental psychology is the relationship between innateness and environmental influence in regard to any particular aspect of development. This is often referred to as “nature versus nurture” or nativism versus empiricism.
A nativist account of development would argue that the processes in question are innate, that is, they are specified by the organism’s genes. An empiricist perspective would argue that those processes are acquired in interaction with the environment. Today developmental psychologists rarely take such polarised positions with regard to most aspects of development; rather they investigate, among many other things, the relationship between innate and environmental influences. One of the ways in which this relationship has been explored in recent years is through the emerging field of evolutionary developmental psychology.
One area where this innateness debate has been prominently portrayed is in research on language acquisition. A major question in this area is whether or not certain properties of human language are specified genetically or can be acquired through learning. The empiricist position on the issue of language acquisition suggests that the language input provides the necessary information required for learning the structure of language and that infants acquire language through a process of statistical learning.
From this perspective, language can be acquired via general learning methods that also apply to other aspects of development, such as perceptual learning. The nativist position argues that the input from language is too impoverished for infants and children to acquire the structure of language. Linguist Noam Chomsky asserts that, evidenced by the lack of sufficient information in the language input, there is a universal grammar that applies to all human languages and is pre-specified. This has led to the idea that there is a special cognitivemodule suited for learning language, often called the language acquisition device.
Chomsky’s critique of the behaviorist model of language acquisition is regarded by many as a key turning point in the decline in the prominence of the theory of behaviorism generally.  But Skinner’s conception of “Verbal Behavior” has not died, perhaps in part because it has generated successful practical applications.  Mechanisms of development Developmental psychology is concerned not only with describing the characteristics of psychological change over time, but also seeks to explain the principles and internal workings underlying these changes.
Psychologists have attempted to better understand these factors by using models. Developmental models are sometimes computational, but they do not need to be. A model must simply account for the means by which a process takes place. This is sometimes done in reference to changes in the brain that may correspond to changes in behavior over the course of the development. Computational accounts of development often use either symbolic, connectionist (neural network), or dynamical systems models to explain the mechanisms of development. Research areas Cognitive development
Cognitive development is primarily concerned with the ways in which infants and children acquire, develop, and use internal mental capabilities such as problem solving, memory, and language. Major topics in cognitive development are the study of language acquisition and the development of perceptual and motor skills. Piaget was one of the influential early psychologists to study the development of cognitive abilities. His theory suggests that development proceeds through a set of stages from infancy to adulthood and that there is an end point or goal.
Other accounts, such as that of Lev Vygotsky, have suggested that development does not progress through stages, but rather that the developmental process that begins at birth and continues until death is too complex for such structure and finality. Rather, from this viewpoint, developmental processes proceed more continuously, thus development should be analyzed, instead of treated as a product to be obtained. K. Warner Schaie has expanded the study of cognitive development into adulthood. Rather than being stable from adolescence, Schaie sees adults as progressing in the application of their cognitive abilities. 13]
Modern cognitive development has integrated the considerations of cognitive psychology and the psychology of individual differences into the interpretation and modeling of development. Specifically, the neo-Piagetian theories of cognitive development showed that the successive levels or stages of cognitive development are associated with increasing processing efficiency andworking memory capacity. In addition, children in higher-levels of cognitive development have been observed to have greater mathematical fluency in basic addition and subtraction problems. 15]
These increases explain differences between stages, progression to higher stages, and individual differences of children who are the same-age and of the same grade-level. However, other theories have moved away from Piagetian stage theories, and are influenced by accounts of domain-specific information processing, which posit that development is guided by innate evolutionarily-specified and content-specific information processing mechanisms. Social and emotional development Developmental psychologists who are interested in social development examine how individuals develop social and emotional competencies.
For example, they study how children form friendships, how they understand and deal with emotions, and how identity develops. Research in this area may involve study of the relationship between cognition or cognitive development and social behavior. Erik Erikson believed we undergo several stages to achieve social and emotional development. These stages were called the Erik Erikson’s Stages of Psychosocial Development. The stages were trust vs. mistrust, attachment, parenting style, ego identity, role diffusion, generativity versus stagnation, midlife crisis, and ego integrity versus despair.
Emotional regulation or ER refers to an individual’s ability to modulate emotional responses across a variety of contexts. In young children, this modulation is in part controlled externally, by parents and other authority figures. As children develop, they take on more and more responsibility for their internal state. Studies have shown that the development of ER is affected by the emotional regulation children observe in parents and caretakers, the emotional climate in the home, and the reaction of parents and caretakers to the child’s emotions.  Physical development
Physical development concerns the physical maturation of an individual’s body until it reaches the adult stature. Although physical growth is a highly regular process, all children differ tremendously in the timing of their growth spurts.  Studies are being done to analyze how the differences in these timings affect and are related to other variables of developmental psychology such as information processing speed. Traditional measures of physical maturity using x-rays are less in practice nowadays, compared to simple measurements of body parts such as height, weight, head circumference, and arm span. 17]
A few other studies and practices with physical developmental psychology are the phonological abilities of mature 5- to 11-year-olds, and the controversial hypotheses of left-handers being maturationally delayed compared to right-handers. A study by Eaton, Chipperfield, Ritchot, and Kostiuk in 1996 found in three different samples that there was no difference between right- and left-handers.  Memory development Researchers interested in memory development look at the way our memory develops from childhood and onward.
According to Fuzzy-trace theory, we have two separate memory processes: verbatim and gist. These two traces begin to develop at different times as well as at a different pace. Children as young as 4 years-old have verbatim memory, memory for surface information, which increases up to early adulthood, at which point it begins to decline. On the other hand, our capacity for gist memory, memory for semantic information, increases up to early adulthood, at which point it consistent through old age. Furthermore, our reliance on gist memory traces in reasoning increases as we age.