Some theorists believe that there are many different possible developmental paths one could take, and that the specific path an individual follows may be determined by their sex, orientation, and when they reached the onset of puberty. Stanley Hall The formal study of adolescent psychology began with the publication of G. Today, it has flipped: It is also relevant in social cognition, resulting in increased introspection , self-consciousness , and intellectualization in the sense of thought about one's own thoughts, rather than the Freudian definition as a defense mechanism. Metacognition A third gain in cognitive ability involves thinking about thinking itself, a process referred to as metacognition. Freud believed that the psychological disturbances associated with youth were biologically based and culturally universal while Erikson focused on the dichotomy between identity formation and role fulfillment. Research also indicates that baseline sensation seeking may affect risk-taking behavior throughout the lifespan. One possible factor is the economy: Adolescence is a sensitive period in the development process, and exposure to the wrong things at that time can have a major effect on future decisions. Darwin's evolutionary theory and Freud's psychodynamic theory. The first places to grow are the extremities—the head, hands and feet—followed by the arms and legs, then the torso and shoulders. No, she never made any porn videos or posted them online. Accordingly, youth, a period that spans late adolescence and early adulthood, has become a more prominent stage of the life course. Growing up between two of Halifax's predominantly black neighbourhoods, Jade was raised in communities plagued by social problems. Nonwhite and younger teens have led the way in declining birth rates in recent years.