Psychology as known is the study of the mind and the mental process whether in normal or abnormal context. These processes strongly influence human personality and behavior, feelings, thinking, memory and sense of judgment .These are sometimes referred to as mental energy.

Personality, is the sum total of persons constitution (heredity) and in born-tendencies, with influences from environment and education which forms the mental make-up of a person and influences attitude to life e.g. anti-social behaviour.

Psychology seeks to influence all these. A person’s behavior or psychological and mental processes are said to be normal when his attitude and-behavior are appropriate for his age, sex, educational and socio-cultural expectations.

Before any behavior occurs a person reacts psychologically or otherwise to a certain stimuli which may be exogenous (environmental) or endogenous (biological) due to functioning of the mind or body which exerts a personality change. .

In common with medical practice generally individuals are often considered psychologically or psychiatrically normal if no evidence of disorder is clinically evident. An epidemiologist doing a population survey may use an empirical definition of normality and regard as normal everybody who has not seen a psychiatrist or psychologist nor consulted a general practitioner for any nervous ailment during the preceding year.

Another concept of normality at times invoked is an"ideal norm" conveying an aspiration towards a desired state of well being (such as is expressed in the pre-amble to the World Health Organization Constitution)

The third concept is a statistical norm implying the state of most people contained in the community of which the patient is a member. In this sense, without straining after the ideal, we can indicate feature characteristics of psychological or otherwise psychiatric normality in mature adults when the doctor or nurse has additional background information from Prior acquaintance with the patient or members of his family.

A person who has successfully negotiated the sequence of stages in personality development is appropriately autonomous. Remember the stages include; anal stage 9 - 18 months, genital stage 18 months up to 6 years of age, Adolescents, Puberty and Adulthood.

The last stage is when one can manage his/her own affairs and tasks without undue reliance on others and can be depended on to meet obligations and to discharge responsibilities appropriate to his occupation, social circumstances and interests. The statement that a mature person can work, love and play perhaps reflects this capacity for autonomy.

Another feature of normality is accurate self perception, the person not over estimating nor belittling his abilities is a third characteristic; correct reality-testing, the environment being perceived in an undistorted way or manner. A fourth feature of normality is adjustment, the person taking things as they are and making the best of them.

Finally, two qualities of maturity are integration (relative coherence of the parts of personality in contrast to gross self contradictions) and achievement, where a person uses his/her skills and interests in such a way that his efforts are productive.

If you have not encountered a psychological disorder within your immediate family, you have very likely encountered one in your extended family and circle of friends or other people around you. You may not have known the formal psychiatric diagnosis for the problem, and you may not have understood its nature or cause but you knew that something was wrong and that professional help was needed.

Until they are forced to face such problems most people believe that "bad things" happen only to other people. Other people had car accident, other people get cancer and other people get severely depressed. Psychological disorders are part of the human experience touching the life, either directly or indirectly of every person. Many of these problems are treatable and many are preventable.

What is then’ ‘abnormal behavior’ ‘? Think about what you had in mind when you read or used the word abnormal as applied to human behavior .

You can make basis for deciding between" normal" and "abnormal" behavior .The distinction (difference) is often difficult to make. It may even seem arbitrary, yet it is essential that you arrive at a clear understanding of this term to guide you in the understanding of the many varieties of human behavior.