A term introduced by the Swiss psychologist Jean Piaget (1896–1980) to refer to the tendency of young children to focus attention on only one salient aspect of an object, situation, or problem at a time, to the exclusion of other potentially relevant aspects. A classic example is provided by an experiment first described by Piaget in 1941 in The Child's Conception of Number in which a child watches while a number of objects are set out in a row and then moved closer together, and the child is asked whether there are now more objects, fewer objects, or the same number of objects. Most children in the pre-operational stage of development focus on the relative lengths of the rows without taking into account their relative densities or the fact that nothing has been added or taken away, and conclude that there are fewer objects than before. The process of cognitive development by which a child develops from centration to a more objective way of perceiving the world is called decentration, decentring, or decentering. See also conservation.