Any position in an area on the spectrum has developed over time and experience under the influence of many other underlying areas. The spectrum of environmental demands which is placed against our abilities is superimposed to highlight the gap which we must fill. For instance, in order to be independent and productive, we need a house to assist us in supplementing our physical need for warmth and shelter. We need communication and informational devices to learn and supplement our social and intellectual abilities. We need a quiet place to collect our thoughts and introspect, etc.
Abilities develop on top of prior ability and opportunity to progress.
During our development we acquire peaks in some abilities. When the environment demands more than our native abilities supply we have a gap and must supplement the native abilities with Assistive Technologies and Systems. The IRA and the VIRA design and training tools are examples of Assistive Systems. The dynamic nature of the environment and our abilities means that the spectra grow and shrink as time and circumstances change. We may have an accident, the economy may decline, a cold winter may occur, we may complete a level of education, we may be called on to play a recital, we may have additions to or deaths in our families.