PSYCHOLOGICAL ASPECTS OF MAN’S ENVIRONMENT 1035
takes time, so that several days may be required to adapt
fully to a change in shift.THE DESIGN OF ENVIRONMENTSThis section will be concerned with the design of physical
environments for maximum human comfort. A later section
will be concerned with psychology’s role in the design of
environments in a broader sense, as in urban planning.
A great many human engineering studies have been
done on special environmental problems. Anthropometric
measurements have been gathered to facilitate the design of
objects used by humans, and a great deal of information is
available on the integration of this information with special
problems, such as designing handles for use with gloves.
Information about the size and movement of various parts of
the body are important to proper design of a wide variety of
furnishings and equipment, from chairs to work areas.
The proper display of information is another important
aspect of proper environmental design. Studies have shown
that certain types of dials are read more easily than others.
Airplane roll indicators which used a fixed artificial horizon
with the position of the plane varying have been shown to
be more easily interpreted than indicators which keep the
plane steady and move the horizon, though the latter design
had been commonly used. A good deal of information about
desirable features of scales has been obtained, and some
useful principles obtained. For example, operators should
not have to transform information before using it. Jet aircraft
tachometers, for example, may be calibrated in percentage
rpm rather than actual rpm so that the pilot need not remem-
ber the maximum rpm for different engines in order to inter-
pret the information.
Many other factors go into the proper display of informa-
tion. For example, if color coding is used, it must be remem-
bered that, while the visual system is able to discriminate
a very large number of colors, in the sense of being able to
say they are different if both are presented simultaneously,
the number that can be correctly distinguished when only
one is presented and memory must be used is far more lim-
ited. The exact number will depend on the colors, viewing
conditions, and other factors such as training, but is unlikely
to reliably exceed ten in many situations and may be much
lower. Knowledge of these and many other aspects of visual
and auditory perception are necessary for the safe and effi-
cient design of many facets of our environment.
Another important problem is the proper integration of
human operators into complex man–machine systems. Here
again, knowledge of man’s information processing capaci-
ties is important. Such questions as the speed with which
an operator can respond, the probability of his detecting
warning signals under various conditions of display and
frequency, his tracking abilities with various displays and
types of targets, are merely samples of the types of questions
which arise and which have been extensively studied.
It should not be assumed, however, that such consider-
ations are important only in military or industrial situations.Proper design considerations are important for the safety
and comfort of the consumer as well. One study showed,
for example, that different burner-control linkages on stoves
resulted in different error rates even after a number of trails.
Agreement among auto manufacturers on the arrangement of
controls in cars with automatic transmissions is an example
of the importance of establishing conventions for the design
of widely used products. The list of consumer products with
features whose design will affect either comfort or safety is
very long indeed.
The information processing capacities of humans are
important considerations in the design of any environment.
The information processing capacities of any organism,
including man, are limited. In such areas of environmen-
tal concern as urban planning, traffic control, etc., such
considerations can be very important. Man is capable of
remembering enormous amounts of information, and per-
forming feats of processing which defy the most complex
machines, but his capacity for short term information pro-
cessing is distinctly limited. A large number of studies
have been done on the problem of human attention and the
effect of information over-loads on various performances.
The results are quite consistent in showing very great limi-
tations to man’s short term information processing capaci-
ties. Exceeding these capacities will result in more or
less serious performance decrements. For example, DAF
(delayed auditory feedback) studies have shown that mis-
matches in input information can greatly degrade perfor-
mance. Individuals have only a very limited capacity for
responding to different information input simultaneously
to the two ears.
Consideration of man’s information processing capaci-
ties should be made in planning facilities for human beings.
In particular, if new environments are being proposed, a
very careful study should be made of their information pro-
cessing demands. However, concern should not be limited
to unusual environments. Badly planned highway signs,
which require a driver to attend simultaneously to too much
information and make too many decisions too rapidly are
an obvious, and unfortunately all too common, example of
failure to consider man’s information processing capacities
in designing the environment. The adequacy of instructions
and cautions in connection with the use of equipment or
potentially hazardous substances may also require consid-
eration of certain of man’s information processing capaci-
ties. Court cases have hinged on the adequacy of cautions
regarding the use of equipment to inform potential users of
hazards.
There are psychological aspects to the design of larger
aspects of the environment. A classic study done on a stu-
dent housing project at MIT showed that social groupings
were significantly influenced by the physical arrangement
of the apartments. Other aspects of modern building design
may be important. For example, most large modern build-
ings are air-conditioned today. Air conditioning may affect
the ionic balance of the air and some concern has been felt
that it may produce symptoms such as depression, though the
evidence to date is inconclusive.C016_012_r03.indd 1035C016_012_r03.indd 1035 11/18/2005 11:03:54 AM11/18/2005 11:03:54 AM