Civil Engineering Reference
In-Depth Information
FIGURE 1.3
Ergonomics systems
model for measurement of safety and
productivity.
focus in ergonomics and should be described in an organizational context, which is the
purpose of Figure 1.3. The figure illustrates the most important operator concepts. In
reality, human perception, information processing, and response are much more complex,
with many feedback loops and variables that are not dealt with here.
In HFE research studies, a classification of independent and dependent variables is
used to analyze a problem. Chapter 3 describes the methodology used in HFE research.
For example, we may study the effect of environmental factors on operator performance.
The characteristics of the environment (such as noise and heat) are independent variables
that we can manipulate through design, and the measures of operator performance are the
dependent variables. One common operator performance measure is the time it takes to
assemble a widget. Another measure is the number of errors committed by the operator
per hour. One can also ask the operator what he or she thinks about the new design—how
good it is and how satisfying it is to work with. Satisfaction—rated on a seven-point
scale—would be a third type of dependent variable.
The operator perceives the environment mainly through the visual and auditory senses,
then considers the information, makes a decision, and, finally, produces a control
response. Perception is guided by the operator's attention. From the millions of bits of
information available, the operator will attend to the information that would seem to be
the most relevant to the task. Some attentional processes are automatic and subconscious
(pre-attentive) and are executed instantaneously (Neisser, 1967). They are so automatic
that the operator will not be able to tell what happened. Some other processes become
automatic only after training, while some require deep thinking and pondering of
alternatives and hence require more time to analyze.
