Conservation (psychology)

Conservation refers to a logical thinking ability which, according to the psychologist Jean Piaget, is not present in children during the preoperational stage of their development at ages 2–7, but develops in the concrete operational stage at ages 7–11. Conservation refers to the ability to determine that a certain quantity will remain the same despite adjustment of the container, shape, or apparent size.

Conservation tasks test a child’s ability to see that some properties are conserved or invariant after an object undergoes physical transformation. The following tasks also explain the different types of conservation. Piaget proposed that children's inability to conserve is due to weakness in the way children think during the preoperational stage (ages 2–6). This stage of cognitive development is characterized by children focusing on a single, salient dimension of height or length, while ignoring other important dimensions about a situation. Children during this stage also tend to focus on the static characteristics of objects, instead of focusing on when objects undergo changes, which is a critical element of the following tasks.

Piaget’s most famous task, the conservation of liquid task involved showing a child two beakers A1 and A2, both of which were identical and which contained the same amount of colored (typically blue) liquid. Then liquid from the second glass A2 was poured into two taller, thinner glasses B1 and B2. The child was then asked whether there was still the same amount of liquid in both the new glasses (B1 and B2) as in the first glass A2. A child who cannot conserve would answer "no, there is more in the tall thin glasses," while a child who can conserve would answer "yes, there is still the same amount." Piaget also replicated this task with beads in glasses, and found again that some children were able to conserve while others were not.

For conservation of number, the task designed to test children involves a set of several marbles. These marbles are placed into two parallel lines that are the same length. Then the researcher spreads out the marbles in one line, longer than the other. Lastly the researcher asks "Is there the same number or a different number in both lines of marbles?" A child that cannot conserve, will answer that there are more marbles in the longer line, while a child that can conserve will recognize that there are the same amounts of marbles in both lines.

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