Human behavior is the collection of actions or reactions exhibited by human beings in relation to the environment, and it can be categorized as either innate or learned. In psychology, behavior became an important construct with the advent of behaviorism, a theoretical framework that required the study of only observable facts or events which can be seen or manipulated, in response to external or internal stimuli. More recently, the Relational Frame Theory (RFT) suggests that also some psychological events such as thoughts and emotions can be explained as learned responses. In TACT project, behavior is the voluntary movement of reaching and grasping in a fixed condition.