Abnormal Human Development: Definition & Examples

  • 0:05 Defining Abnormal Development
  • 1:00 Deciding What…
  • 2:47 Examples of Abnormal…
  • 3:40 Lesson Summary
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Lesson Transcript
Instructor: Lisa Roundy

Lisa has taught at all levels from kindergarten to college and has a master's degree in human relations.

Abnormal development occurs when a person develops an unusual pattern of behavior, emotion or thought. In this lesson, you will learn what abnormal development is, how it is determined and examine different examples.

Defining Abnormal Development

Most of what is studied in developmental psychology is related to understanding how and why people change and grow. This helps us understand how typical development occurs, so we can help this growth take place in positive ways. But, what happens when someone's development does not fit our understanding of what is normal?

Kate has noticed that her daughter has not learned to speak as well as most other children her age. Other 3-year olds can say that they are thirsty and ask for a drink. Kate's daughter still points to the refrigerator and cries. This has Kate concerned. Is her daughter's behavior because her development is abnormal?

When development occurs in an unexpected way and exhibits an unusual pattern of behavior, emotion or thought, it's called abnormal development. This is an important area of study because of the effects abnormal development has on individuals and society.

Deciding When Development Is Abnormal

Abnormal development can occur at different stages of our lives and can present itself in different ways. The effects can vary, and the impact of abnormal development on a person's normal life ranges from mild to severe. There is also some variance as to what constitutes normal development. So, how do you know when to consider an individual's development abnormal?

Developmental psychologists use different tools to assess how much a person's development differs from what is considered to be normal. These tools are called assessments.

For example, let's imagine your grandfather has been forgetting things a lot lately. He visits the doctor to see if something is wrong. His doctor asks him to remember three words that he will have to recall later. Then, your grandfather is asked to draw a picture of a clock. When your grandfather finishes drawing the clock, the doctor has him repeat the three words that he was asked to remember. If your grandfather recalls all three of the words, his memory is functioning normally. If he only recalls one or two words, the doctor may run more tests to see if there is an abnormality.

This example is a simple test that can be used to assess memory. Just like in the example above, the information obtained from different assessments of individual functioning is used to determine whether there is enough difference to consider a person's development abnormal. For development to be considered abnormal the following is usually true:

  • Symptoms involve a disturbance in behavior, thought or emotion
  • Symptoms are associated with personal distress or impaired functioning
  • The symptoms have a biological or psychological basis

Examples of Abnormal Development

When abnormal development occurs, it falls in to one of three categories: emotional, cognitive or physical. Let's look at some examples of each of these categories.

Abnormal emotional development occurs when a person is depressed, anxious or lacks social skills. An example of this would be a person suffering from a mood disorder, a person with an anxiety disorder or a person with a developmental disability, such as autism.

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