Developmental Psychology: Key Concepts and Stages

Developmental Stages in Psychology

Sensorimotor and Preoperational Periods

The sensorimotor and preoperational periods are the first two stages in Jean Piaget's theory of cognitive development, describing how children's thinking evolves from birth through early childhood.

• Sensorimotor Period (Birth to ~2 years): Infants learn about the world through sensory experiences and motor actions. They develop object permanence—the understanding that objects continue to exist even when out of sight.

• Preoperational Period (~2 to 7 years): Children begin to use language and think symbolically, but their thinking is still intuitive and egocentric. They struggle with conservation—the idea that quantity remains the same despite changes in shape or appearance.

• Example: A child in the preoperational stage may believe that pouring water from a short, wide glass into a tall, thin glass changes the amount of water.

Concrete Operational and Formal Operational Stages

Piaget's later stages describe the development of logical thinking and abstract reasoning in children and adolescents.

• Concrete Operational Stage (~7 to 11 years): Children gain the ability to think logically about concrete events. They understand conservation and can classify objects according to several features.

• Formal Operational Stage (~12 years and up): Adolescents develop abstract reasoning and hypothetical thinking. They can solve problems systematically and think about future possibilities.

• Key Concepts: Conservation (understanding that quantity is conserved despite changes in shape) and Object Permanence (objects exist even when not perceived).

• Example: A teenager can reason about abstract concepts like justice or freedom.

Attachment and Social Development

Variations in Attachment Behaviors

Attachment refers to the emotional bond between a child and caregiver. Psychologists identify different attachment styles using the Strange Situation Test.

• Secure Attachment: Children feel safe and confident to explore when their caregiver is present, and are comforted by their return.

• Insecure Attachment: Includes avoidant, ambivalent, and disorganized styles, where children may show anxiety, avoidance, or confusion in relationships.

• Strange Situation Test: A procedure developed by Mary Ainsworth to observe attachment relationships between a caregiver and child.

• Example: A securely attached child may cry when the parent leaves but is quickly comforted upon their return.

Harlow and Attachment

Harry Harlow's experiments with rhesus monkeys demonstrated the importance of comfort and emotional security in attachment.

• Key Finding: Monkeys preferred soft, cloth surrogate mothers over wire ones that provided food, highlighting the role of contact comfort.

• Application: Emotional bonds are crucial for healthy psychological development.

Moral Development

Preconventional, Conventional, and Postconventional Levels of Moral Reasoning

Lawrence Kohlberg proposed three levels of moral reasoning, describing how individuals' ethical thinking matures over time.

• Preconventional Level: Morality is based on avoiding punishment and seeking rewards.

• Conventional Level: Morality is based on social rules and the approval of others.

• Postconventional Level: Morality is based on abstract principles and the recognition of universal ethical values.

• Example: At the postconventional level, a person may break a law to uphold human rights.

Prenatal Development

Stages of Prenatal Development

Prenatal development occurs in three main stages, each critical for the formation of the human body and brain.

• Germinal Stage (Zygote): The first two weeks after conception, involving cell division and implantation.

• Embryonic Stage (Embryo): Weeks 3-8, when major organs and structures begin to form.

• Fetal Stage (Fetus): Week 9 to birth, characterized by growth and maturation of tissues and organs.

• Example: The heart begins to beat during the embryonic stage.

Teratogens and Fetal Alcohol Syndrome

Teratogens are substances that can cause harm to a developing fetus, leading to birth defects or developmental disorders.

• Teratogens: Include drugs, alcohol, tobacco, certain infections, and environmental toxins.

• Fetal Alcohol Syndrome (FAS): A condition resulting from maternal alcohol consumption during pregnancy, characterized by physical abnormalities and cognitive impairments.

• Example: Children with FAS may have facial deformities and learning disabilities.

Identity and Psychosocial Development

Developing an Identity: Erikson's Stages

Erik Erikson's theory of psychosocial development outlines eight stages, each characterized by a central conflict that must be resolved for healthy psychological growth.

• Key Stages:

  • Trust vs. Mistrust (Infancy): Developing trust in caregivers.

  • Autonomy vs. Shame and Doubt (Toddlerhood): Developing independence.

  • Initiative vs. Guilt (Preschool): Asserting control and power.

  • Industry vs. Inferiority (School Age): Mastering skills and knowledge.

  • Identity vs. Role Confusion (Adolescence): Developing a sense of self.

  • Additional info: Erikson's theory continues through adulthood, addressing intimacy, generativity, and integrity.

• Example: Adolescents explore different roles and beliefs to form their personal identity.

Language Development

Language Acquisition in Childhood

Language development is a critical aspect of cognitive growth, involving the ability to understand and produce language.

• Stages: Babbling, one-word (holophrastic) stage, two-word stage, and telegraphic speech.

• Key Theories: Nativist Theory (Chomsky: innate language ability), Learning Theory (Skinner: reinforcement and imitation), and Interactionist Theory (combination of innate ability and social interaction).

• Example: Children typically say their first words around 12 months and rapidly expand vocabulary in early childhood.

Summary Table: Major Developmental Stages

Stage	Age Range	Main Features
Sensorimotor	Birth - 2 years	Object permanence, sensory exploration
Preoperational	2 - 7 years	Symbolic thinking, egocentrism, lack of conservation
Concrete Operational	7 - 11 years	Logical thinking, conservation, classification
Formal Operational	12 years and up	Abstract reasoning, hypothetical thinking
Additional info: Erikson's Stages	Infancy - Late Adulthood	Psychosocial conflicts (e.g., identity, trust, autonomy)