Adolescence Stage of Development: Definition & Explanation

Lesson Transcript
Instructor: Chris Clause

Chris is an educator with a background in psychology and counseling. He also holds a PhD in public affairs, and has worked as a counselor and teacher for community college students for more than 10 years.

The stage of human development known as adolescence occurs in the range from 10 to 21 years approximately. Define the developmental stage of adolescence and explore the different changes that occur during this stage, including physical, cognitive, and socio-emotional changes. Updated: 09/10/2021


Human growth and development is characterized by several distinct and unique stages beginning with conception and ending at death. Like all stages of human development, adolescence is an important stage. In this lesson, we will focus on the biological, cognitive, and socio-emotional aspects of adolescence, which make it unique and distinguishable from the other stages of human development.

For most humans, adolescence begins around age 10 to 12 and concludes somewhere between 18 to 21 years of age. It is important to remember that age alone does not signify the beginning and end of adolescence, but rather achieving key developmental milestones indicates when a particular stage of development has begun or concluded.

While a variety of changes are taking place during adolescence, these changes can, for the most part, be classified within three major categories:

  • Physical
  • Cognitive
  • and Socio-emotional aspects

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  • 0:00 Adolescence
  • 1:04 Physical Development
  • 1:34 Cognitive Development
  • 2:34 Socio-Emotional Development
  • 3:45 Lesson Summary
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Physical Development

The onset of puberty marks the beginning of the significant physical changes that occur within the developmental stage of adolescence. Puberty encourages rapid physical growth and is triggered by the increased production of two hormones:

  • Testosterone in males
  • and Estradiol in females

By the end of adolescence the body has, for the most part, undergone the changes needed to result in a fully functioning adult being including physical maturity and sexual development in both genders.

Cognitive Development

As the body changes and grows during adolescence, the brain undergoes significant changes as well. Specifically, certain areas of the brain grow and develop independent of one another during adolescence. Recent brain imaging studies have shown that the amygdala, which is influential in emotional regulation, develops earlier in adolescence, and the cortex, which is influential in thinking and decision-making, occurs later in adolescence.

Renowned developmental psychologist, Jean Piaget, posited that the hallmark of adolescence, from a cognitive perspective, is the ability to engage in formal operational thinking. In general, formal operational thinking involves the ability to understand abstract concepts and the ability to make predictions about future events. In the eyes of cognitive developmental psychologists, the ability to perform functions requiring formal operational thinking, such as developing theories and solving abstract problems, marks the transition into adolescence.

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