An approach to psychometrics that attempts to measure not only the products or processes of learning but also the potential to learn. It focuses on the difference between latent capacity and developed abilities, or the extent to which developed abilities reflect latent capacity, and it seeks to quantify the psychological processes involved in learning and change, rather than the products of such processes, by presenting sequences of progressively more challenging tasks and providing continuous feedback on performance in an atmosphere of teaching and helping that guides the testee towards the right answer. Credit for introducing the concept is usually assigned to the Russian psychologist Lev Semyonovich Vygotsky (1896–1934) who discussed it in Thought and Language (1934). Also called dynamic assessment. See also Learning Potential Assessment Device, Lerntest, zone of proximal development. Compare static assessment environment.