The Preoperational Stage of Cognitive Development

The preoperational stage is the second stage in Piaget's theory of cognitive development. This stage begins around age 2, as children start to talk, and lasts until approximately age 7.

During this stage, children begin to engage in symbolic play and learn to manipulate symbols. However, Piaget noted that they do not yet understand concrete logic.

The preoperational stage occurs roughly between the ages 2 and 7. Language development is one of the hallmarks of this period. Piaget noted that children in this stage do not yet understand concrete logic, cannot mentally manipulate information, and are unable to take the point of view of other people, which he termed egocentrism.

During the preoperational stage, children also become increasingly adept at using symbols, as evidenced by the increase in playing and pretending. For example, a child is able to use an object to represent something else, such as pretending a broom is a horse.

Role-playing also becomes important— Children often play the roles of "mommy," "daddy," "doctor," and many other characters.

Piaget used a number of creative and clever techniques to study the mental abilities of children. One of the famous techniques to demonstrate egocentrism involved using a three-dimensional display of a mountain scene. Often referred to as the "Three Mountain Task," children are asked to choose a picture that showed the scene they had observed.

Most children are able to do this with little difficulty. Next, children are asked to select a picture showing what someone else would have observed when looking at the mountain from a different viewpoint.

Invariably, children almost always choose the scene showing their own view of the mountain scene. According to Piaget, children experience this difficulty because they are unable to take on another person's perspective.

Other researchers have also conducted similar experiments. In one study, children were shown a room in a small dollhouse. Children were able to see in the dollhouse that a toy was hidden behind a piece of furniture. Children were then taken into a full-size room that was an exact replica of the dollhouse. Very young children did not understand to look behind the couch to find the toy, while slightly older children immediately searched for the toy.

Developmental psychologists refer to the ability to understand that other people have different perspectives, thoughts, feelings, and mental states as theory of mind. 

Another well-known experiment involves demonstrating a child's understanding of conservation. In one conservation experiment, equal amounts of liquid are poured into two identical containers. The liquid in one container is then poured into a differently shaped cup, such as a tall and thin cup or a short and wide cup. Children are then asked which cup holds the most liquid. Despite seeing that the liquid amounts were equal, children almost always choose the cup that appears fuller.

Piaget conducted a number of similar experiments on the conservation of number, length, mass, weight, volume, and quantity. He found that few children showed any understanding of conservation prior to the age of five.

As you might have noticed, much of Piaget's focus at this stage of development focused on what children could not yet do. The concepts of egocentrism and conservation are both centered on abilities that children have not yet developed; they lack the understanding that things look different to other people and that objects can change in appearance while still maintaining the same properties.

However, not everyone agrees with Piaget's assessment of children's abilities. Researcher Martin Hughes, for example, argued that the reason that children failed at the three mountains task was simply that they did not understand it. In an experiment that involved utilizing dolls, Hughes demonstrated that children as young as age 4 were able to understand situations from multiple points of view, suggesting that children become less egocentric at an earlier age than Piaget believed.