What are Piaget's stages?

Hello, I'm a specialist in developmental psychology, and I'm here to provide you with a detailed explanation of Jean Piaget's stages of cognitive development. Piaget's theory is one of the most influential frameworks for understanding how children's thinking changes as they grow older. His theory is based on the idea that children progress through a series of distinct stages, each characterized by a unique way of thinking about the world. Let's delve into each of these stages:

**1. Sensorimotor Stage (Birth through ages 18-24 months)**
The sensorimotor stage is the first stage of Piaget's cognitive development theory. During this stage, infants understand the world primarily through their senses and physical movements. This stage is further divided into six sub-stages:

- **Sub-stage 1: Simple Reflexes (Birth-6 weeks)**: Newborns respond to light, sound, and touch with reflexes such as sucking and grasping.
- **Sub-stage 2: Habituation (6 weeks-4 months)**: Babies begin to show a preference for familiar stimuli over new ones and start to habituate to repeated stimuli.
- **Sub-stage 3: Purposeful Activity (4-8 months)**: Infants start to engage in intentional actions, such as reaching for objects and exploring their environment with their hands and mouth.
- **Sub-stage 4: Means-Ends Behavior (8-12 months)**: Babies begin to use means to achieve an end, such as pulling a blanket to reach a toy that's out of direct reach.
- **Sub-stage 5: Tertiary Circular Reactions (12-18 months)**: Children start to engage in repetitive activities for their own sake, not just to achieve a goal.
- **Sub-stage 6: Symbolic Representation (18-24 months)**: The emergence of symbolic thought is marked by the use of objects to represent other objects or ideas, such as pretending a block is a telephone.

**2. Preoperational Stage (Toddlerhood through early childhood, 18-24 months to age 7)**
The preoperational stage is characterized by the use of language and the beginning of symbolic thinking. However, children in this stage still think intuitively and egocentrically, meaning they have difficulty taking the perspective of others. This stage is further divided into two sub-stages:

- **Sub-stage 1: Symbolic Function (18-24 months to 2-4 years)**: Children begin to use symbols, such as words and pictures, to represent objects and events.
- **Sub-stage 2: Intuitive Thought (2-4 years to 7 years)**: Children start to engage in more complex forms of symbolic play and thought, but their thinking is still largely intuitive and not yet logical.

**3. Concrete Operational Stage (Ages 7 to 12)**
During the concrete operational stage, children begin to think logically about concrete events and to understand the concept of conservation (the idea that certain properties, like quantity or volume, remain the same despite changes in appearance). They can perform operations, but these operations are tied to concrete objects and events, not abstract concepts.

**4. Formal Operational Stage (Adolescence through adulthood)**
The formal operational stage is marked by the ability to think abstractly and to consider hypothetical scenarios. Adolescents and adults in this stage can reason logically and systematically, not just about tangible objects but also about abstract concepts and possibilities.

Piaget's theory has been influential in shaping our understanding of cognitive development, but it's important to note that it has also been subject to criticism and refinement over the years. Some researchers argue that Piaget underestimated children's abilities, while others suggest that the stages may not be as distinct or universal as Piaget proposed.

Now, let's move on to the translation of the above explanation into Chinese.

Piaget's four stages of intellectual (or cognitive) development are:Sensorimotor. Birth through ages 18-24 months.Preoperational. Toddlerhood (18-24 months) through early childhood (age 7)Concrete operational. Ages 7 to 12.Formal operational. Adolescence through adulthood.