The architecture of light: architectural lighting design concepts and techniques. A textbook of procedures and practices for the architect, interior designer and lighting designer pdfdrive com

Using Phototropism to draw attention
As discussed in Chapter 2, phototropism is the understanding that human beings are attracted to light as a matter of instinct. This simple instinct can be relied upon to draw attention to the surfaces and spaces with which we want people to interact. Phototropism suggests that despite conditioning and expectation, in a room full of detailed furniture, intricate flooring, wall coverings and tile mosaics, the object that the casual observer will notice first is the shaded table lamp glowing in the corner. With this understanding, we realize that we have predictable control over where a viewer’s attention is drawn in our designed spaces. Phototropism dictates that the eye of the observer will move from the brightest surface to the next brightest surface. It means that we can often convince an observer that a space is bright by simply drawing his/her attention to a few large, bright surfaces.
Lighting Vertical Surfaces
The third tool of human perception on which we rely is the premise that the human visual system is designed to translate the light reflecting off of the surfaces in an environment. The eyes aren’t able to do much with the high levels of light that come directly from a light source. Thus, the perception of the brightness of a space has more to do with the light detected from the surrounding surfaces than the brightness of the light sources. This concept is exemplified by a stage performer under a spot light. This person has a large amount of light cast onto him/her, but he/she still feels like they are in the dark. Another example is a simple room with a glowing chandelier in the middle. The chandelier may attract attention, but it does not necessarily make a space feel bright.
Because we are upright, standing creatures, we rely on the light reflecting from the vertical surfaces that make up our surroundings and define our peripheral vision. In most of our day to day activities, our field of vision is focused directly in front of us. Even when we look around us, we are using the upright, vertical surfaces of our surroundings to define our environment. The feelings of confinement or freedom and overall light quality are defined by the conditions of the walls, horizons ceilings, and sky conditions around us. The only time we look down is to assess the safety of the path in front of us, so the only time we really need to apply light downward and immediately around us is to illuminate such paths.
Humans do not define brightness by the light level on the ground around
them, nor do they define brightness by the light focused directly onto them. As upright, mobile creatures geared to learn from reflected light, humans naturally focus on upright, reflective surfaces around them to define their impression of an environment. If the goal is to create an impression of brightness, light applied to vertical surroundings is much more effective than light directed on the viewer.
Figure 3.1 Light applied to vertical surfaces (left) increases the perception of brightness compared to the same amount of light applied to horizontal surfaces (right).