Transcript Age differences in visual abilities in nighttime driving

Age differences in visual abilities in
nighttime driving field conditions
Professor: Liu
Student: Ruby
Objective
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This study was to provide field data on age
differences in sign easy for read and object
detection.
Different age groups were tested for
nighttime visual ability.
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References
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The hazard detection have primarily
focused on the effects of roadway lighting.
(Janoff & Staplin, 1987)
Most studies discussed the visual function
and inferences are drawn about the
impkications of age differences and driving
safety. (Ball & Owsley, 1997; Shinar & Schieber, 1991)
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References
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Older drivers’ easily read distances were
65-77% of younger drivers. (Sivak, Olson, &
Pastalan, 1981)
The studies examining age differences,
used Landolt rings to measure the easily
read. (Olson & Bernstein, 1997)
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Method
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Participants
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Older driver group-10 participants.
 53-75 years old (average of 65.6 years)
Younger drivers group-10 participants.
 19-25 years old (average of 22.5 years)
All participants had corrected acuity of 20/25 or
better.
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Method
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Field Site and Conditions
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This experiment consisted of three roads:
 Road A --- was used for sign easily read
assessment which included two sign easily read.
(the length was 2000 feet)
 Road B --- was used for hazard detection. (the
length was 500 feet)
 Road C --- was used for the pedestrian detection
task. (the length was 1000 feet)
Using photometric to measure the peripheral light
at each night of testing.
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Method
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Apparatus1/2
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A 1993 Ford Taurus vehicle.
A Numetrics Nitestr distance measuring instrument
was used to record visibility distances.
Three visibility conditions were tested:
 Standard clear weather.
 Simulated inclement weather wear a plastic
visor.
 Glare  a set of standard headlamps mounted
oncoming in the opposite travel lane.
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Method
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Apparatus2/2
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The easily read task consisted of an 8’’Landolt ring
Placed on a 24’’ sign background.
The object detection task consisted of two objects.
 The small road hazard object was an upsidedown bowl measuring 7’’ high and 13’’ wide.
 The pedestrian object was a child-sized 3’6’’tall.
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The average reflectance clothing was gray clothing.
The low reflectance clothing was dark red.
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Method
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Experimental design
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One lap through the test course 2 sign easily read
and 2 object detection.
Each participants completed 2 practice laps and 16
experimental laps.
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Method
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Procedure
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Participants were seated in the front passenger seat
of the test vehicle.
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Participants were called out the position of the gap
or the position of the object as soon as they could.
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When the participants response, the experimenter
would press the Numetrics and record the distance.
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Results
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Sign easily read 1/2
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Results
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Sign easily read 2/2
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Young group correctly identified the Landolt gap 147
feet further away the older group at clear weather.
The younger group average was 467 feet and the
older group average 320 feet.
 older group read the signs at 65% of the distance
of the younger group.
The young group average was 192 feet while the
older group was 126 feet. (at SIW situation.)
The older group’s distance as a percent of the
younger group’s performance was again 65%.
There were no significant main effects for easily
read distance under SIW.
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Results
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Small road hazard detection 1/2
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Results
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Small road hazard detection2/2
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The gray object across age groups had longer
detection distances. (p=0.066)
The older group’s detection distances were 78% of
the younger group.
The presence of glare headlights significantly hurt
the detection distances of both ages, an average
37% reduction.
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Results
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Pedestrian detection 1/2
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Results
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Pedestrian detection2/2
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The gray clothing was significant longer detection
distances for both age groups.
The older group’s detection distances were 75% of
the younger group.
The SIW reduced the detection of pedestrian targets
fro both groups by 37%.
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Discussion
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Older drivers have reduced easily read and
object detection distances when compare
to a younger group of people.
The glare conditions results severe
pedestrian detection losses for the older
groups.
participants were significant showed their visual
search for the target in a range, which forced them
to look more directly into the glare headlights.
(Shinar & Schieber, 1991)
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