Cognitive advances encompass both increment in knowledge and in the ability to think abstractly and to reason more effectively.
The study of adolescent development often involves interdisciplinary collaborations.
Pubescent boys often tend to have a good body image, are more confident, secure, and more independent.
Late maturing boys can be less confident because of poor body image when comparing themselves to already developed friends and peers.
Facial hair is often present in late adolescence, around ages 17 and 18, but may not appear until significantly later.
Consequently, girls who have a high-fat diet and who are not physically active begin menstruating earlier, on average, than girls whose diet contains less fat and whose activities involve fat reducing exercise (e.g. They have the advantage in capturing the attention of potential partners and in becoming hand-picked for sports.
In studying adolescent development, adolescence can be defined biologically, as the physical transition marked by the onset of puberty and the termination of physical growth; cognitively, as changes in the ability to think abstractly and multi-dimensionally; or socially, as a period of preparation for adult roles.
Major pubertal and biological changes include changes to the sex organs, height, weight, and muscle mass, as well as major changes in brain structure and organization.
Physical growth (particularly in males), and cognitive development can extend into the early twenties.
Thus age provides only a rough marker of adolescence, and scholars have found it difficult to agree upon a precise definition of adolescence.
In addition to changes in height, adolescents also experience a significant increase in weight (Marshall, 1978).