Collins accounts the span of developmental psychology in three separate periods, the emergent period (1890-1919) in which interest was first shown in the area of child development with Darwin’s baby diaries (1876), and some early empirical studies. The second period stated by Collins is the middle period (1920-1946) this period saw the introduction of theory into the area of development, for example from behaviourist and psychoanalysis as well as a large increase in the amount of research being done. The last period is the modern period which Collins states we are still in. his period started in 1947 and has seen the largest developments in the subject of child development with large steps being taken in theories methodologies and analytic procedures. (Collins, as cited in Smith, Hart 2002) As in many areas of psychology the theories surrounding developmental psychology are divided into a few, distinct schools of thought. These theory divides include Freud’s psychoanalytical theories, the nativist viewpoint, the Associatonist Assumption and the constructivist viewpoint. All are interested in how the child develops throughout their lives, however each takes a distinct viewpoint on how that change comes about. Freud was the founder of psychoanalytical theories and although some people disagree with his viewpoints, it is safe to say he has had a huge effect on the way we see psychology today. He claimed that unconscious forces that come from within a person, determine a child’s development. He suggested that there are four main states that determine how a child develops into adult life, he called these stages the psychosexual stages. Theses stages include the oral stage, the Anal stage, the Phallic Stage and the Latency stage. He claimed that if a child’s development was halted or disturbed in any of these stages then it could cause problems in later life. For example if a child did not properly develop through the first oral stage then the could become orally fixated in later life which could cause them to be more likely to take up smoking or suck their thumb to a late age. Freud claimed that three main structures called the id, the ego and the super ego develop subconsciously through these psychosexual stages. He claimed it is these three structures that are responsible for our needs, desires and controlling them. The id is said to be present in newborns and is responsible for impulses such as desires and emotions, the ego then develops to act as a mediator for the mind, so we just don’t follow these impulses from the id. The superego develops last and is responsible for our sense of duty and responsibility, almost like a conscious. This theory is quite problematic because these are unconscious processes that cannot be proven or disproven. By Freud’s analysis anyone who would deny these stages is simply in denial (Slater, Bremner. 2003). . The Nativist or ethological viewpoint states that humans are pre disposed by their genetic makeup to develop in a certain way, or develop a certain set of attributes, whether it be intelligence, language or attachment. This predisposition to certain behaviours stems from evolutionary work with genes. This theory states that humans are restrained in their development by their genetic makeup (Slater A, Muir, D, 1999). This viewpoint was influenced by Darwin’s Origin of species, in which his observation of slight changes in behaviour and form led to his groundbreaking origin of species theory. It was with this viewpoint in mind that he observed his own child’s development in his ‘baby diaries’ and attempted to detail his son’s early development. (Slater. Muir. 1999). Mary Ainsworth and John Bowlby were also interested in the evolutionary development in children, and they carried out a number of experiments which they called the strange situation. They discovered that from a very early age children have a primary need or drive to bond with one significant person, usually the mother , and that there are different types of attachment a child can have. From these experiments Ainsworth and Bowlby developed the Attachment theory. Support for the nativist theory of development can be found in language development studies. The nativist viewpoint suggests that humans are predisposed to learn language and are ‘genetically wired with knowledge of language’. Nativist’s believe that a language acquisition device (LAD) is responsible for allowing children to understand rules governing speech from an early age, which makes a complex task such as learning a language easier for young children. There are other universal processes that lend themselves to the nativist viewpoint, for example development as a whole eg, age of starting to try to walk and talk tend to be the same across cultures and demographics. (Cairns 1996, Crain 1993, as cited in Harmon, Jones 2005). It was not until the 1920’s and 30’s that the nativist viewpoint began to lose weight against new behaviourist or associatonist assumptions, which states that a persons development is shaped by their environment, this viewpoint states that when a person is born they are like a blank slate and it is their experience of their environment that shapes their development. This is a mechanacalistic viewpoint, which sees humans as totally passive in their development. The theory states that people develop through learning, which is initiated by using specific stimulus, response connections. This theory has been widely supported by Pavlov’s classical conditioning studies (1926). he found that he could successfully condition dogs to salivate at the sound of a bell when the bell had previously been rang to coincide with feeding time. , this came about through learned association. (Pavlov, 1926, as cited in Klein S, Mowrer, 1989). This study supported the idea that people are conditioned to learn to develop in a certain way through stimulus, response connections. Skinner (1904-1990) had a huge effect on the area of behaviourism. He rejected the assumption of his peers that a child was completely passive in his or her development, he accepted that a child’s environment played a large role in their development, however his operant conditioning theory allowed more flexibility in the fact that it allows that the children emit behaviours on their environment as well as their environment on them. He claimed that children can be shaped by manipulating the reinforcements they receive. For example a parent can elicit bad behaviour by giving attention to a child only when he/she is behaving bad. Watson and Arnold Gesell were also prominent researchers in behaviourism and their belief that conditioning accounted for all learned behaviours stirred up the development debate. Albert Bandura’s theory of social learning came after Pavlov’s work with dogs, his was a much less mechanistic than previous behaviourist theories. He carried out a series of experiments using children to see the affect of reinforcement on aggression. He found that when a group of children had watched a film of an adult being aggressive to a BoBo doll and then were allowed to play with the same doll they copied the aggressive ction, perceiving a reinforcement as there was no obvious reinforcement present. This experiment kept the essential parts of the behaviourist assumption, however it also incorporated learning by observation. This theory used the idea that there are internal workings governing learning as well as simple, reinforcement response, which behaviourists had denied until this time. (Bandura 1960, as cited in Slater,Bremner, 2003) The fourth viewpoint I will discuss is the constructivist viewpoint. This theory state that humans are active participants in what they learn, thus their development. It says that humans have an innate ability to use emotion and intelligence to make sense of the world around them, using schemas, expectations of the world based on previous, similar experiences, to fill in the gaps in knowledge and experience. Therefore a person’s internal viewpoint is individual to them as it is gained from personal experience and internal representations. Piaget was a constructivist who believed that children were not blank slates as behaviourists had suggested, but instead their development is motivated intrinsically not extrinsically. He stated in his theory ‘Adaptation’ that through the processes assimilation and accommodation a child learns to adapt to the world around them, thus developing their knowledge of the world, and skills to live (Slater, Bremner. 2003). ‘Assimilation’ is when a child uses his or her schemas of the world to help them in a new situation, giving them cues on how to behave. ‘Accommodation’ is where a child has to adjust their schemas slightly to accommodate new, more detailed information about a person or experience. The two always coincide as the assimilation helps a child deal with a new experience but then the schema has to change because no two different experiences are the same. These processes are called functional invariants, as they don’t change during development. (Slater, Bremner, 2003) Piaget (1962) outlined four broad stages of cognitive development. The Sensimotor period (birth to two years) in this stage the child develops ’thoughts in action’ they learn that their actions have consequences and so learn to solve problems. The second stage, which is called the preoperational stage, from2 to 7 years. In this stage children learn to solve a number of problems by using intelligence and tools. They develop communication skills through drawing and symbols. However they find it difficult to see things from other people’s point of view. The third stage is called the concrete operations stage; this takes place between ages seven and eleven. This is where the ability to focus the attention on one aspect of a situation and exclude others. The formal operations stage (from about 11 years) sees the child becoming able to solve complex problems and using hypothetical thought to hold complex discussions, weighing out responses like scientists do. Slater,Bremner. 2003). Developmental psychology has seen many shifts in popularity in the approaches used to explain the development of humans. Psychologists such as Skinner, in his social learning theory, have incorporated two types of theory, for example social and behavioural, however the different poles of learning all still hold relevance today although their seems to be no unified discipline that incorporates all schools of learning.