 Consequently, the majority of his work involved the study of infant and child behavior, as well as the development of language acquisition (such as the importance of pointing and inner speech) and the development of concepts; now often referred to as schemas or schemata.Early in the psychological research period of his career (1920s), which focused upon mechanistic and reductionist "instrumental psychology" in many ways inspired by the work of Ivan Pavlov (his theory of "higher nervous activity") and Vladimir Bekhterev (and his "reflexologist" followers), Vygotsky argued that human psychological development could be formed through the use of meaningless (i.e., virtually random) signs that he viewed as the psychological equivalent of instrument use in human labor and industry.It was later during the "holistic" period of his career (the first half of the 1930s) that Vygotsky rejected this earlier reductionist views on signs.