degrees of stimulation or arousal. The more
stimuli that must be processed by a person,
the higher the load. Environments that are
complex, crowded, asymmetrical, novel, unfa-
miliar, surprising, or random are high load.
Environments that are simple, uncrowded,
symmetrical, conventional, familiar, unsur-
prising, or organized are low-load.
If the task to be performed is complex or
unusual—studying technical material, pre-
paring for an exam, or writing an essay—the
load is great enough that our degree of
arousal is fairly high; additional load from the
environment will increase stimulation to
such a point that the task is avoided. We
become distracted, annoyed, or frustrated,
and performance falls off sharply.
Tasks that are simple or routine—writing
checks, making a shopping list, or other
familiar chores—benefit from a mildly stimu-
lating environment. Daydreaming or dozing
may result without increased stimulation.
This is why such work often fails to be per-
formed in home offices or studies designed
for paperwork; instead it is done in kitchens,
dining rooms, or living rooms, which have a
higher degree of stimulation.
The lower the load of the task, the more
it requires a high-load setting for optimum per-
formance. Boring tasks are boring because
they are unstimulating (simple or overly famil-
iar) and often unpleasant. Within reason, the
more stimulation provided, the more pleasant
the task becomes. For many, basic housework
is monotonous; playing background music
increases stimulation, enabling us to complete
“boring” domestic chores.
Degrees of Brightness Contrast
The degree of brightness contrast evokes
emotions in the same way as background
music. It affects the performance of tasks,
influences the behavior of people at work
and at play, and impacts the amount of con-
tentment and pleasure we experience. The
degree of brightness contrast establishes
the emotional setting, which either rein-
forces or undermines the intended activity.
The first step in the lighting design pro-
cess is to identify the activity that will occur
in a space. The second step is to determine
a degree of stimulation that will reinforce
that activity. The third step is to establish the
degree of brightness contrast that will yield
the necessary level of stimulation.
Brightness contrast is established by
developing patterns of light and shade—by
selecting specific surfaces and objects to
receive lighting emphasis while leaving others
in comparative darkness. This emphasis cre-
ates the relationship between foreground
and background (figure 2.1).Low-Contrast Environment
If everything is to receive equal emphasis, no
hierarchy is established between foreground
and background. The result is alow-contrast
environment. Low-contrast spaces are low in
stimulation: few stimuli exist to respond to.
These spaces are behaviorally neutral (figure
2.2).
A large proportion ofdiffuselight and a
small amount offocusedlight produce this
low-contrast environment. Low-contrast light-
ing systems are intended to provide easy
seeing for visual tasks, to allow random circu-
lation, or to permit flexible relocation of work
surfaces. The diffuse lighting technique pro-
vides a uniformly illuminated working environ-
ment, an area suitable for difficult and
sustained visual tasks (figure 2.3).
Lighting systems that flood a space with
diffuse light from overhead reduce contrast.
Highly diffuse light produces a shadowless
environment; forms are ill-defined and tex-
tural perception is poor. Although this is ade-
quate for task vision, it ignores the problem
created by the bland psychological reaction
to a cloudy day.INTERIOR LIGHTING FOR DESIGNERS