This stage was tested in 
This stage was tested in Polynesian canoe-users by Gladwin, who found that western tests were culturally inappropriate. According to Case, it is driven by vectorial control structures. One method of testing for this stage is asking where a subject would place a third eye, with patients in this stage suggesting the hand. One test of this stage was developed by Robert Siegler, and involved a balance. Inhelder developed a task involving a (*) pendulum and several lengths of string to test for it. Meta-cognition and trial-and-error testing arise during this stage, which may not be universal and is characterized by the ability to understand abstract symbols and hypothetico-deductive thinking. For 10 points, name this fourth stage in Piaget's (pee-ah-JAYZ) theory of cognitive development, which follows the concrete operational stage.
This stage was tested in Polynesian canoe-users by Gladwin, who found that western tests were culturally inappropriate.
formal operational [or formal thinking]