Basic research on purpose is aimed at testing the PCT model of purposeful behavior. These tests are performed to validate detailed predictions about the relationships between the variables involved in purposeful behavior. The main focus of the research is testing for controlled variables using some version of the TCV. Laboratory tests for the controlled variable are typically conducted using versions of the compensatory tracking task, where all of the variables involved in the behavior can be readily identified and monitored. Other approaches to testing for controlled variables in the laboratory have used operant conditioning tasks which have been set up so that the system under study is capable of controlling the consequences of its actions. It is also possible to do basic research on purpose in more naturalistic settings outside the laboratory, which allows the study of more “realistic” behaviors.