Theories abound about how people develop emotionally, intellectually, socially, and spiritually. This essay will examine the theories of five leaders on the topic of development. Jean Piaget believed in four stages of development whose description was quite concrete (Atherton, 2010).1. Sensorimotor stage (birth – 2 years) – Children begin to make sense of the world around them based on their interaction with their physical environment. Reality begins to be defined.2. Preoperative stage (2 to 7 years) – Concrete physical stimuli are necessary for a child to develop new concepts.3. Concrete Operations (ages 7-11) – As a child gains experience with the physical world, they begin to conceptualize to explain these experiences. Abstract thinking also emerges.4. Formal operations (from 11-15 years) – Conceptual reasoning is present and the child's cognitive abilities are similar to those of an adult (Atherton, 2010). Piaget was firm in his conception of these stages. He believed that a person should progress from one stage to another, that it was a natural biological process influenced by environment and experiences. Biology limits time, but the environment determines the quality of development. Lev Vygotsky's stages of development were not defined by age or biology. Social and cultural experiences formed the basis of his theory. Consciousness was the end product of social interactions (Kearsley, 1994-2010). The child's societal history and his or her own personal history determine the way the child thinks. Language is crucial for development, because it is with words that a child conceptualizes and makes sense of the world (Schütz, 2004). A precept of Vygotsky's theory was...... middle of paper ......f the environment and how it influenced human development. Jensen also emphasized the impact of emotions, positive interactions and stress on brain function and growth. “Working cooperatively can enhance learning” (Jensen, 2005, p. 96). “Good learning engages feelings” (Jensen, 2005, p.80). This concept is consistent with Vygotsky and Erikson's emphasis on social engagement. Kohlberg and Gilligan also based their theories of development on social experiences. The inclusion of emotions as essential to learning, “providing incentives for desired behavior” (Jensen, 2005, p. 69) could be compared to the importance of desired moral reasoning. The end product of moral reasoning is a particular behavior, and as a person learns or completes a stage, the behavior becomes increasingly socially acceptable or desirable..