Visual field (1), preferred visual field (2) and optimum field of vision (3) of a person standing and sitting for vertical visual tasks.
Preferred field of vision for horizontal visual tasks. Preferred angle of view 25°.
We are not however, conscious of every object that comes within our field of vision. The way the fovea prefers to focus on small, changing scenes shows that the perception process purposefully selects specific things to look at. This selection is inevitable, as the brain is not capable of processing all the visual information in the field of view. It also makes sense because not all the information that exists in our environment is necessarily relevant to us.
The value of any particular information relates to the current activity of the observer. This activity may be work or movement-related or any other activity for which visual information is required. Lighting conditions under which the visual task can be perceived to an optimum degree can be determined from the above-mentioned specific features. It is possible to define ways of lighting which will be ideal for specific activities.