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Four
Emperical Field Experiments
Study
Method and Findings
In the eight months prior to our study the Fire Department had rejected
28 applicants for failing the vision requirements. Standards were not
tied to the job via job analysis and existing standards were considered
far too strict by firefighters.
The need for a standard for vision in the absence of corrective lenses
(an uncorrected standard) is determined by the need for the firefighter
to do the job safely on those occasions when corrective lenses are
missing. Setting a fair standard requires balancing two demands: 1)the
need for safety and protection of firefighters and the public, and 2)
the avoidance of unfair discrimination against firefighter applicants
who can perform the job adequately, even though they lack perfect
vision.
Our review of existing vision research turned up no studies which would
have allowed transportability of findings. Several research hers have
provided empirically valid police vision standards. In contrast, it
appears that vision standards for firefighters have not been based on
formal analyses of the visual demands in firefighting. Further, few
tasks performed by police are also performed by firefighters, except
driving and driving-related tasks, therefore, transporting police
vision standards transporting police vision standards to firefighters
is inappropriate.
Our research program followed several phases. We performed a survey of
firefighters to determine breakage of glasses and the consequences
thereof. All career and volunteer firefighters were surveyed. Of the
814 career and approximately 800 volunteer firefighters 525 surveys
were returned. Response rate for career firefighters was 80 percent.
Later, critical firefighter vision tasks were empirically determined by
a survey of 29 glasses-wearing experienced firefighters. These raters
were asked to rate each task on its consequences if not performed. The
tasks were than rank ordered by relative importance. simulations of the
most important tasks were created with the assistance of fire service
training experts. Those most important vision tasks included spotting a
victim of the roof, spotting a human victim behind the window on the
fourth floor, reading codes on a tanker, and identifying dangerous
elements in an artificially lit room from a distance of 20 feet during
overhaul.
Subjects were six career firefighters who had 20/20 vision. All had
between 5 and 13 years of first-line firefighter experience. Age ranged
from 21 to 31. The repeated measure experimental designs provided
statistical power (the ability to detect a true effect) in excess of
.80. Firefighter subjects were clinically decorrected to four levels of
acuity by standards opthalmic technique. The levels spanned the
gradations between the then current uncorrected standard for the better
eye (20/40) and the lowest level judged feasible (20/200).
On the day of the field testing, we first field-tested firefighter
subject's uncorrected vision and their vision with each pair of glasses
at 20 feet to verify the decorrection levels. Each simulation took
place on a separate side of the training building at the fire academy,
so subject firefighters could not see the next simulation. No
firefighters were present during the testing of any other firefighters.
Scoring criteria for each simulation were established in advance;
subsequent comparison of independently assigned scores revealed an
interrater agreement of 100 percent on each simulation. We assessed
each firefighters' performance on each of the simulated critical tasks
at each of the five levels of acuity: 20/20; 20/40; 20/70; 20/100; and
20/200. Trials began at 1:00 PM and ended at 7 PM on July 7, 1988.
An expert panel, composed of fire chiefs, fire training officers, and
one psychologist, had determined acceptable cutoff scores for adequate
performance for each simulation. Firefighters performed at levels
judged satisfactory at binocular acuity levels (both eyes open) of
20/100 in two simulations and 20/200 in the other two simulations.
Statistical analysis (single factor univariate anovas) revealed large
differences in performance due to acuity, with F values ranging from 6
to 62, but little difference due to intra subject variability.
The results of the field experiments (the four simulations) clearly
indicated the appropriateness of radical changes in existing selection
standards. Based on the findings of this research program, we
recommended setting the uncorrected static distance vision standard at
20/100.
This recommendation was reviewed by the National Fire Protection
Association Medical Subcommittee and adopted in 1992. The far visual
acuity standard in NFPA 1582 is based on this MED-TOX study.
Note: This
paper was originally presented at the International
Personnel Management Association Assessment Council 13th Annual
Conference held in Orlando, FL in June of 1989.
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