 Let's consider the following scenario. Three-year-old Timmy has started making his own breakfast at cereal each morning. Cereal often ends up on the kitchen floor, and he regularly spills the milk when he's pouring it into the bowl. When his mother tries to make cereal for him, Timmy becomes angry and he shouts at her, No! I can do it! Why is Timmy behaving this way? Has Timmy learned this behavior, or are his actions related to his age, family relationships, or personality? Questions like these are what developmental psychologists try to answer. They seek to understand and explain the behavior that occurs throughout our lives. A number of different theories have been developed in an attempt to explain the various aspects of human growth. Developmental theories provide a set of guiding principles and concepts that describe and explain human development. By better understanding how and why people change and grow, we can help this growth take place in positive ways. One of the most influential theories of human development is psychoanalytic theory. Many modern theories of counseling or psychotherapy are extensions, modifications, or reactions against psychoanalytic theory. Psychoanalytic theory examines the factors that motivate behavior by focusing on the role of the unconscious. Sigmund Freud and Eric Erickson are examples of theorists who support this approach. Freud was a pioneer with his psychoanalytic theory of personality and his psychosexual development theory. Erickson expanded Freud's theories in many ways and developed his own theory of psychosocial development. Psychoanalytic theory's strength lies in its awareness of unconscious motivation and the importance of early experiences on development. Unfortunately, the ideas involved are difficult to test. Because of this, psychoanalytic theory does not have substantial research available to support its ideas. Remember Timmy? Psychoanalytic theory might explain his behavior by saying that he's seeking independence and he's acting in an age-appropriate way for the developmental stage that he is experiencing. As a reaction to the lack of empirical evidence to support the claims of psychoanalytic theory, psychologists became increasingly interested in developing a more scientific approach. In order to do this, some researchers began to study only those things that could be measured and quantified. This led to the emergence of learning theories. Learning theories focus on how behavior is learned. Let's look at some individuals who develop theories that focus on how people learn new behaviors. Ivan Pavlov studied learning through association in his theory of classical conditioning. B. F. Skinner examined the effects of reinforcement and punishment in his theory of operant conditioning. Albert Mandura considered the effects of behavior modeling in his social learning theory. The major strength of behavioral learning theories is their ability to be tested and to be practically applied. The main weakness of these theories is that they generally ignore the effect of the genetic processes and changes that occur throughout the human lifespan. Think back to Timmy's behavior again. Learning theory might explain his actions as a learned response. Timmy knows that if he tries to make his own cereal when his mother's around, she will try to help him. If he acts out when she does this, he gets the attention that he is seeking. His mother's attention reinforces the response and he learns to repeat the acting out behavior to gain her attention. Another way to look at human development is through cognitive development theories. Cognitive development theories are concerned with the development of thought processes and how these thought processes influence our understanding of the world around us. A major figure in cognitive development theory is Jean Piaget. He revolutionized the way we look at child development by proposing the idea that children think differently than adults. Piaget's stages of cognitive development look at the sequential steps that take place in children's intellectual development. Cognitive behavioral theories are supported by research and are influential in parenting and in the field of education. However, a weakness of the theory is the limited consideration of emotional factors. Remember Timmy? A cognitive theorist might explain Timmy's behavior as a learning process. Timmy is developing a better understanding of shapes and logic, but his worldview is still egocentric. Timmy's attempts to make his own cereal show both the development of an understanding of how to perform the task and also a self-centered desire to do it without assistance. Human development can also be examined as a product of the interaction of complex systems that influence an individual. Theories that support this view are known as systems theories. Systems theories look at how people interact with their environments and how these interactions relate to biological factors and to behavior. There are several approaches to developmental systems theory. Evolutionary developmental psychology is the application of Charles Darwin's theory of evolution and natural selection to the process of human development. Gilbert Gottlieb is an important figure in epigenetic psychobiological systems perspective, which views development as a product of interaction between biological and environmental forces. Ecological systems theory was developed by Uri Bronfenbrenner. This theory divides the environment into different systems that interact to influence the development of an individual in some way. Systems theories' main strength is its emphasis on the interaction of many different factors in determining development. This is also its main weakness because the complex interactions taking place are difficult to test scientifically. Let's think about Timmy again. Systems theory might explain his behavior as being in effect of the interactions in his environment. Timmy's father travels often because of his work. This causes Timmy to seek attention at home when his father is away because he's anxious. Attempting to make his own breakfast is one way that Timmy can seek the attention that he desires when his father is sent away on a business trip. Perhaps now Timmy's mom can understand better the possible reasons for Timmy's behavior. She has learned there are a number of different ways to think about his actions. The best fit for the situation could be a psychoanalytic theory, it could be a learning theory, a cognitive development theory, or a systems theory. Each developmental theory provides a set of guiding principles and concepts that describe human development. Timmy's mother may choose a different way to deal with the situation depending on which theory she thinks is the best fit. The purpose of using a developmental theory to help her is to help Timmy's growth.