The pattern of light on walls and ceilings and floors affects us psychologically. In several studies going back to John Flynn in the early 1970s, intensity and uniformity of light in a space create impressions of visual clarity, spaciousness, preference, relaxation, and privacy. For example, to make an office space appear larger and brighter, it helps to wash the walls and ceilings with light. To make a restaurant look more private and romantic, light should be kept away from walls and ceilings except as accent on artwork or features. Uneven lighting patterns on the work plane (table tops) reinforce the feeling of romance and privacy.
Conversely, an uneven pattern of light on the floor and walls of a parking garage may make the space appear unsafe, because the patron may not be able to see potential danger in the shadowy areas. Patterns of light have a dramatic influence on human perceptions, so it is important to anticipate where a luminaire will direct its light.