Jean Piaget is perhaps one of the most well-known and influential child development specialists. His work was first published during the 1920's, but his theory of cognitive development continues to influence contemporary researchers and clinicians. Piaget's identified five characteristic indicators of adolescent cognitive development and named them as follows: 1) formal operations, 2) hypothetico-deductive reasoning, 3) propositional thought, 4) the imaginary audience, and 5) the personal fable. A more detailed explanation of Piaget's theory can be found in the Child & Adolescent Overview article. Here we limit the discussion to portions of his theory directly related to cognitive development in adolescents.
Piaget used the term "mental operations" to describe the mental ability to imagine a hypothetical situation and to be able to determine a likely outcome, without needing to actually observe or enact the scenario. This is commonly called a "What if--?" scenario. For instance, suppose a 7-10 year old child is asked, "What if there was a hungry dog in the kitchen and Mother dropped a hotdog on the floor. What do you think would happen?" Most children at this age will correctly guess that the dog ate the hotdog, particularly if they have any experience with dogs. Piaget called this type of mental operation a "concrete operation" because the mental operation represents a tangible, concrete circumstance that the child can easily imagine since it is anchored to things that can be seen and touched in the real world: It is concrete.
According to Piaget, the adolescent years are remarkable because youth move beyond the limitations of concrete mental operations and develop the ability to think in a more abstract manner. Piaget used the term "formal operations" to describe this new ability. Formal operations refer to the ability to perform mental operations with abstract, intangible concepts such as "justice" or "poverty" and to be able to estimate or describe the effect of these intangible concepts. Therefore, youth can now represent in their mind circumstances, or events that they have never seen, nor personally experienced. For instance, a youth who has reached the stage of formal operations can imagine and accurately describe what it may have been like to be a poor, black resident of New Orleans during Hurricane Katrina and can imagine and describe how victims may have felt about the inadequate and disparate rescue efforts. This youth will be able to use the abstract concepts of injustice and poverty to imagine and describe these events.
Piaget's research found that youth entered the stage of formal operations at approximately 11 years of age on average; however, there is a great deal of individual variation with respect to normal development. Children's cognitive development can be affected by many factors such as family culture; the quantity and quality of formal schooling or training; various medical conditions; and emotional or physical trauma. If parents have concerns about their children's lack of developmental progress, they will want to discuss these concerns with their children's health care provider, and other professionals such as teachers, guidance counselors, and school administrators. If these professionals believe there is cause for concern, they may refer the child for psychological testing for further assessment. More information about psychological assessments for children can be found here.
Hypothetico-deductive reasoning and propositional thought
In addition to the ability to perform abstract mental operations, teens become more scientific and logical in the way they approach problems. Piaget called this methodical, scientific approach to problem-solving, "hypothetico-deductive reasoning." Youth can now consider a problem, or situation, and can identify the many variables that may influence or affect the outcome. They can also estimate the most likely outcome if one or more variables are changed or manipulated. This ability has very practical applications because it enables youth to select the most logical or sensible solution to a problem.
To illustrate the value of hypothetico-deductive reasoning, consider the following example: A teenage boy, Aaron, decided he'd like to surprise his Mom and bake her some cookies. Unfortunately, the first batch didn't turn out so well- the cookies were burnt. In order to solve this problem Aaron will mentally review the ingredients he used, and the steps he took to bake the cookies. Aaron will consider the variables that typically cause burnt cookies such as omitting a key ingredient, an improper oven temperature, or leaving the cookies in the oven too long. Next, Aaron will imagine changing each individual variable in order to determine the most likely cause of the burnt cookies, and he will subsequently decide what he needs to do differently. For instance, Aaron may decide that the most likely cause of the burnt cookies was that he left them in the oven too long. So, for the next batch of cookies Aaron will set the timer for a shorter period of time. After the second batch is finished, he will then evaluate if this solved the problem or whether he needs to change a different variable. However, if Aaron's younger brother James were to try and solve the burnt cookie problem, James would try to change several variables all at once, by adding more milk, changing the baking time, and changing the oven temperature. This is because younger children cannot think about possible solutions to the problem without trying out the solutions, and younger children do not know how to solve problems in a logical and methodical manner by changing one variable at a time.
According to Piaget, another complicated thought process that adolescents master is called "propositional thought." This means youth can determine whether a statement is logical based solely on the wording of the statement, rather than having to observe or re-create the actual scenario to determine if it is logical. For example, suppose Uncle Marty told his 14-year-old niece Jaime, "I have one piece of money in my wallet for you. It's a $5 bill, and it's a $20 bill." Jaime would automatically know her uncle was joking around with her because she knows this statement is illogical simply by the way it is worded: A single American money bill cannot represent two different denominations of money. However, suppose Uncle Marty were to say the same thing to his 7-year-old nephew Andrew. Andrew would not automatically understand the impossibility of this sentence and would need to see the money in his uncle's wallet to decide if he was trying to tease him or not.
The imaginary audience and the personal fable
Not only do adolescents become more scientific and logical, but they also become better students of observation and interpretation. By observing other people's behavior, expressions, comments, and appearance they can interpret this information and make reasonable guesses about what another person may be thinking, wanting, needing, or feeling. As such, adolescents also begin to wonder about what other people may be thinking about them! Unfortunately, these new cognitive abilities appear at the same time that younger adolescents are struggling with insecurities about their changing appearance, changing identity, and changing life experiences. All of these factors combine to create what Piaget called the "imaginary audience." Teens may mistakenly believe that everyone around them is watching and judging them, scrutinizing their every move, and can become painfully self-conscious as a result. The concept of an imaginary audience helps parents to understand why their teenagers spend eons in front of the bathroom mirror just to run to the store for a short errand, or become incredibly embarrassed over a seemingly minor mistake. Therefore, the imaginary audience provides an example of the inter-relationship between cognitive, emotional, and social development.
While the ability to use abstract thought and keen observational skills enables youth to become more attuned to others and more sensitive to people's needs, it can also lead to some new social and emotional difficulties when youth use their new cognitive abilities to compare themselves to others. Youth may feel exceptionally unique and different from other people, including their own peers. Piaget called this the "personal fable." Many teens believe they have unique abilities, or conversely, unique problems, different from anyone else in the world. Some youth feel as though they are better, smarter, or stronger than others. This personal fable can lead to some devastating consequences because these youth may take dangerous risks when they over-estimate their abilities and believe they can "handle it," or mistakenly believe they are omnipotent and that bad things cannot happen to them. This is why it is important for adult caregivers to continue to monitor youths' behavior, choices, and decisions.
Conversely, other youth may feel as though they are dumber, weaker, and inferior to others. This kind of personal fable can lead to feelings of sadness, frustration, and loneliness. If these negative thoughts and feelings continue to strengthen, youth can become depressed or hopeless, which can lead to other dangerous behaviors such as drug use, unsafe sexual activity, or even suicide. Once again, these youth need their caregivers' love, guidance, and support to help them through these difficult circumstances. More specific information about emotional development can be found later in this article.
While Jean Piaget's theory has greatly advanced our knowledge and understanding of cognitive development, some parts of his theory have not withstood the rigors of contemporary research. This newer research has resulted in some modifications to his theory. For instance, recent research has demonstrated that everyone does not reach the stage of formal operations (the ability to think abstractly), as Piaget once believed (Keating, 1979; Cole, 1990). Furthermore, research suggests that if abstract thinking isn't practiced frequently, or isn't needed on a daily basis, the skill may never fully develop. Even when someone has acquired the ability to think abstractly, research has revealed that most adults can only think abstractly in a few specific domains such as specific areas of expertise, education, or other areas of special interest (Lehman & Nisbett, 1990). Thus, adults are less able to think abstractly about unfamiliar topics and concepts.