A term introduced in 1931 by the Russian psychologist Lev Semyonovich Vygotsky (1896–1934) to denote the distance between a child's ‘actual developmental level as determined by independent problem solving [and the higher level of] potential development as determined through problem solving under adult guidance or in collaboration with more capable peers’. Vygotsky believed that it is most likely to emerge during play. See dynamic testing. Also called the zone of potential development. ZPD abbrev.