Conservation (psychology)

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Conservation refers to a logical thinking ability which, according to the psychologist Jean Piaget becomes evident in children aged 7–12 during the concrete operational stage of their development. It is part of Piaget's theory of cognitive development, to logically 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, such as a row of coins being stretched out, or a spherical lump of clay being rolled into a tube. Conservation itself is defined as: the ability to keep in mind what stays the same and what changes in an object after it has changed aesthetically. One who can conserve is able to reverse the transformation mentally and understand compensation.

Piaget’s most famous task, the Conservation-of-Liquid (there are many others e.g. conservation of substance, weight, number etc.) involved showing a child two beakers, both of which were identical and which contained the same amount of coloured (typically blue) liquid. The child was asked whether the two beakers had the same amount of liquid in both. Then liquid from one of the glasses was poured into a taller, thinner glass. The child was then asked whether there was still the same amount of liquid in both glasses. A child who cannot conserve would answer "No, there is more in the tall thin glass".

Piaget furthered the conclusion to suggest that this confusion was born from a pre-operational child’s inability to understand the notion of reversibility; the ability to see the reversal of a physical transformation as well as the transformation itself. These ideas were used to create the ‘Principle of Invariance’.


The Conservation Task (and hence Piaget's theory) has been criticized on a number of fronts: that answers reflect the children's cultural expectations and the context of interchanges with adults, and children's understanding of the word "more".

The ages at which children are able to complete conservation tasks has been questioned by subsequent research. Research has suggested that asking the same question twice leads young children to change their answer as they assume that they are being asked again because they got it wrong first time around.[1] The importance of context was also emphasised by researchers who altered the task so that a 'naughty teddy' changed the array rather than an experimenter themselves. This seemed to give children a clear reason for the second question being asked, and 4 year old children were able to demonstrate knowledge of the conservation of matter, much earlier than Piaget's reported 7-11 year old threshold for Concrete Operations.[2] (See Bower, 1974, Object Permanence.)

Cross-cultural differences found in the Conservation Task, (and in Formal Operational tasks, among others) led Piaget (1972)[3] to revise his claim of universal stages, allowing for contextual variability, depending on experience in particular domains.

For example: North African Wolof adolescents tested by Greenfield (1966) responded that the quantity of water in a conservation test had changed.[4] However Irvine (1978)[5] suggests that their interpretation of the experimenter’s purpose may have conflicted with giving straightforward answers to the standard Piagetian questions because - except in school interrogation - Wolof people seldom ask questions to which they already know the answers. Irvine states: “Where this kind of questioning does occur it suggests an aggressive challenge, or a riddle with a trick answer” (1978, p. 549). When Irvine presented the task as language-learning questions about the meaning of quantity terms such as "more" and "the same", the responses reflected understanding of conservation. (from Rogoff 2003, p. 247-248)[6]


  1. ^ Rose, S.A. & Blank, M. (1974). The potency of context in children’s cognition: An illustration through conservation. Child Development, 45(2):499-502.
  2. ^ McGarrigle, J. & Donaldson, M. (1974). Conservation accidents. Cognition, 3, 341-350.
  3. ^ Piaget, J. (1972). Intellectual evolution from adolescence to adulthood. Human Development, 15, 1-12.
  4. ^ Greenfield, P.M. (1966). On culture and conservation. In J.S. Bruner, R.R. Olver, & P.M. Greenfield (Eds.), Studies in cognitive growth. New York: Wiley.
  5. ^ Irvine, J.T. (1978). Wolof “magical thinking”: Culture and conservation revisited. Journal of Cross-Cultural Psychology, 9, 300-310.
  6. ^ Rogoff, B. (2003). The Cultural Nature of Human Development. New York: Oxford University Press.