A pleasurable response, centred on an external object, that is discovered by chance and performed over and over: coordination of secondary schemes (8-12 months) Infants begin to coordinate two or more actions to achieve simple objectives. This is the first sign of goal-directed behaviour: tertiary circular reactions (12-18 months) objects to reproduce interesting results, symbolic problem solving (18-24 months) An exploratory scheme in which the infant devises a new method of acting on. Theory theories: piaget"s account of infant development is generally accurate although somewhat, neo-nativism incomplete. Theories of cognitive development that combine neo-nativism and constructivism, proposing that cognitive development progresses by children generating, testing and changing theories about the physical and social world. The preoperational stage (2-7 years) and the emergence of symbolic thought. Preoperational period: when children are thinking at a symbolic level but are not yet using cognitive operations. Symbolic function: the ability to use symbols (ie. images and words) to represent objects and experiences.