Legal Issues in Occupational Ergonomics - Fundamentals and Assessment Tools for Occupational Ergonomics - page 34

of losing a job if there was a refusal to do unsafe work, possible human error, and the allocation of
human fault. The expert's deposition took two full days to cover all of the human factors issues
that the opposing counsel thought was relevant to the accident.
Another expert witness testified about a vehicle control or handling problem that may have led to an
accident. The vehicle manufacturer had some written design objectives about driver handling parameters
that were used as a reference. In essence, the vehicle should compensate for driver overreactions or exces-
sive steering wheel inputs, and remain stable under all operational conditions including accident avoid-
ance maneuvers. In addition, the vehicle should signal or give the driver some perceptible signals when
the vehicle handling limits are approached. There should be sufficient stability and predictability that the
driver will not lose control of the vehicle and initiate an accident situation. There were questions as to
how human factors considerations, in a vehicle stability index, could assure controllability and have a
reasonable margin of safety in resisting rollover, tipover, and side slip or slide. The expert was asked
about reasonable design parameters and limits, given various risk-benefit balances, the technical feasi-
bility at the time of manufacture, the cost implications, and the effects on customer satisfaction. Also,
what constitutes an adequate perceptual signal to the driver and what is likely in terms of the driver reac-
tion? Many questions relied upon the subjective judgment of the expert, others upon extrapolation of
known test results, and others on specific published data. Different experts have varying success in
quick, decisive, and subjective answers. The more experience, the greater credibility of the answer. The
more decisive, the more the jury believes and remembers.
3.2.2 The Prediction of Behavior
The human factors specialist has an occupational focus on human behavior that rejects ill-informed
speculation. Thus, there should be some factual objective basis for any conclusions, recommendations,
opinions, or interpretations as to the cause, characteristics, and predictability of human behavior. The
best approach is ethical targeted research, conducted for a lawsuit, but such testing is often just a
form of advocacy to prove a predetermined point and it can be very deceptive. Independent experimental
research findings can accumulate and permit a conditional relevant application. Probably, the most
understandable for a judge and jury is controlled observational data and conclusions that pertain to indi-
vidual, group, or team performance. In terms of predictive indices or equations, a best fit for the available
data may be helpful. Whatever the analytic process, there should be some objective data that serves as a
foundation for an opinion.
The human factors psychologist, by training and experience, may provide informed guidance on the
critical question of the foreseeability of certain behavior, including intentional error, misuse, abuse,
destructive behavior, and the relative predictability of certain acts of commission or omission.
However, these are ultimate issues of law and fact that pervade many cases and are interpreted differently
by various participants in the legal system. If the prediction of a certain behavior is a question for the jury,
the human factors specialist may assist the jury by defining the factors to be considered in the prediction
of behavior.
The human operator may be just one variable in a machine system. The ergonomic issues may include
the learning and adaptability of a selected or unselected, trained or untrained, machine operator from a
diverse pool of prospective talent and skill. But, all machines are increasingly variable over time, usage,
maintenance, repair, and environmental conditions. How is the operator informed or signaled as to an
approach to decreasing and undesired machine limits? How will the operator respond to out-of-
tolerance, emergency, or panic situations after long-term familiarity with the machine or process? In
driving a company vehicle, is there some warning that the vehicle dynamics are close to the handling
instability limit? This might be an understeer-oversteer gradient of such a character as to permit the
driver to maintain safe control or for an electronic stability control system to actuate. In other words,
questions of human behavior are not isolated, they are intertwined with a specific machine function
or a process control.