Longitudinal approach to the study of development implies repeated observations of phenomena during some time with the object of revealing constant aspects and changes, and also with the object of their explanation.
Longitudinal method is a special kind of observation. Its task is to determine causes of inward individual changes that happen to one person, or to different individuals or to various groups of people.
This approach is considered to be the ideal one for development psychology which can be defined as a science that studies changes that happen in human’ s behavior depending on his age.
The usage of the longitudinal method was closely connected with the growth of development psychology. Indeed, there are a lot of biographies and journals where children’s behavior is described in the process of their development. The longitudinal method was widely used from 1916, when testology appeared.
In order to receive data with the help of longitudinal approach some tests, questionnaires, observation method are used. Time distance between longitudinal measurements depends on the period of life that is investigated. For instance, for an adult person a week is a very short period of time, while for an infant a week is a very considerable period. Advantages of longitudinal approach:
1. Longitudinal method explains changes that happen according to age. Longitudinal method consists in observation or measurement of the same examinees. They are conducted during certain time. That’s why attention is paid to changes that happen inside of the individual, but not to changes that occur between different individuals.
2. This approach admits the comparison with other examinees.
3. Longitudinal approach allows to compare changes that happen under various external circumstances.
4. Higher accuracy in prognosis of psychic development of a certain person and of future process of psychic evolution in general (in comparison with cross-sectional approach).