This study examined how aging adults serialize their behavior when performing complex driving tasks that require monitoring a lead vehicle and attending to peripheral information. Researchers found that when task demands increased in scenarios requiring additional peripheral localization tasks, older adults withdrew attention from the lead vehicle, as shown by lower hit rates on the vehicle monitoring task. Younger adults maintained consistent monitoring across scenarios. Additionally, older adults were less accurate on the peripheral localization tasks. The results suggest that aging adults serialize their behavior by shifting attention away from the lead vehicle to focus processing resources on peripheral tasks, indicating a potential safety risk when monitoring forward movement is disrupted.

1. SERIALIZATION OF CAR FOLLOWING BEHAVIOR
IN AGING ADULTS
Benjamin D. Lester1, Sarah D. Hacker2, Matthew Rizzo4, & Shaun P. Vecera3
1Human
Factors
Prac/ce,
Exponent
Failure
Analysis
Associates,
Phoenix,
U.S.A.;
2Department
of
Neurology,
3Department
of
Psychology,
University
of
Iowa,
Iowa
City,
Iowa,
U.S.A.;
4Neurological
Sciences,
University
of
Nebraska
Medical
Center,
Omaha,
NE,
U.S.A.
In each scenario, drivers
followed a lead veh50, 55,
& 60 M.P.H. at random
intervals. Drivers adjusted
their speed to match the
LV’s speed.
Abstract
Aging drivers may adopt strategies to compensate for effects of
age-related cognitive decline on driving ability. One strategy is to
perform complex driving tasks (such as turns) in discrete steps
(“behavioral serialization”) rather than fluidly. We examined age-
related serialization of behavior using car following scenarios in
a driving simulator. In all scenarios, participants closely
monitored a lead vehicle. In multi-tasking scenarios on a more
cluttered roadway, drivers performed a localization task designed
to increase attention demands. Results showed age-associated
changes in task prioritization in older adults, compatible with
serialization including instances where aging drivers withdrew
attention from the lead vehicle for several seconds. This pattern
of behavior identifies a remediable situation where age-
associated impairments may increase crash risk.
Background
Age-related impairments in allocating attention are commonly observed
when multiple tasks must be coordinated (Kray & Lindenberger, 2000;
Mayer, 2001).
Examine how age-related serialization strategies might impact
behavior during a car following scenario.
Methods
Results
Conclusions
General multi-tasking impairments were observed in aging adults.
Current findings suggest that serialization of behavior may be a general
strategy in aging individuals coping with high task demands while driving.
In this study, aging adults withdrew attention from the LV based on proximity to
peripheral signage. Abandoning forward monitoring of a LV puts drivers at
greater risk for front-end collisions (NHTSA, 2009).
The manner in which adults serialized behavior identifies a specific opportunity
for safety intervention, as with in vehicle collision alerting and warning
systems.
Acknowledgements
This research was supported by a grant awarded from the Toyota Collaborative Safety Research Center (CSRC). We
wish to thank Drs. Nazan Aksan, Satoshi Kitazaki, Jim Foley, and Kazutoshi Ebe for their valuable input. We also thank
Amanda Farmer, Lacy Flanagan, Jessica Ferdig, Rob Marini, Nathan Myhre and Tara Ohrt for assistance with subject
recruitment and data collection.
Subjects
16 neurologically-normal aging drivers (M = 79 years, SD = 5.95) and 19
younger drivers (M = 30.19, SD = 6.11) completed 3 simulated car following
driving scenarios.
Procedure
In each scenario, drivers followed a lead vehicle (LV) that varied its speed
between 50, 55, & 60 M.P.H. at random intervals. Drivers adjusted their
speed to match the LV’s speed.
Car following is a common driving task that can be attentionally
demanding depending on road culture and environmental demands.
Figure 1. Example of sign localization task from the “Locate” and “Ignore” scenarios.
Hit rates for target events were measured during the LV sustained attention
task. Accuracy was calculated for the peripheral localization task
In driving, secondary in-vehicle tasks typically cause greater behavioral
interference in aging adults compared to younger drivers (Wood et al.,
2006; Gaspar et al., 2013; Wild-Hall et al., 2011).
Aging adults are often aware of their cognitive and physical limitations.
These individuals may adopt apparent compensatory strategies to
allocate processing resources during complex tasks (Fovanova &
Vollrath, 2011).
Previous studies report “serialization” of vehicle control during complex
manuevers in older adults (Boer et al., 2011; Thompson et al., 2012)
à Specifically, aging adults performing right turns made steering
and speed adjustments in discrete steps, whereas younger adults
accelerated and steered simultaneously.
à This study uses continuous measures of visual perception and
attentional deployment to examine how aging adults control
information processing resources during car following.
Scenarios
Follow: In all scenarios, sustained attention was directed to the LV.
Drivers monitored the LV’s unpredictable turn signal behavior for “target”
events (e.g., a hazard flash) that were embedded in the driving scenario.
When a target event was detected, drivers pulled the high beams lever.
Follow & Locate: During this scenario, drivers performed an additional
localization task designed to mimic attention to roadway signage. Drivers
verbally reported the perceived location of the target object that appeared
in the periphery.
Follow & Ignore: In this scenario, distractor items appeared in the non-
target positions of the peripheral localization task. These distractors were
used to increase localization difficulty, similar to a cluttered roadway
signage environment.
0.50
0.60
0.70
0.80
0.90
1.00
Follow Follow & Locate Follow & Ignore
Hitrate(proportion)
Sustained attention
Younger
Older
Overall, younger adults had higher hit rates during car following task across all
driving scenarios (p < .01), compared to aging adults. When peripheral
localization was required, aging adults showed a larger drop in hit rates,
compared to younger adults (ps < .001). This suggests when behavioral
demands increased, aging adults withdrew attention from the LV.
0.50
0.60
0.70
0.80
0.90
1.00
Follow
&
Locate
Follow
&
Ignore
Proportioncorrect
Sign localization
Younger
Older
Aging adults were overall less accurate during sign localization (p < .0001),
compared to younger adults. The presence of distractor items did not
significantly impact performance in either age group (p > .05). The results of
the sustained attention and peripheral localization task suggest older drivers
may be withdrawing attention from the LV to serially shift resources to the
periphery. Such a strategy predicts hit rate should vary with distance to a
peripheral localization judgment point.
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Post- Mid- Pre-
Hitrate(proportion)
Time window (300 m sections)
Sustained attention (by distance)
Younger
Older
Aging adults showed a significant drop (p < .05) in LV monitoring as they
approached a localization point (“pre-judgment”). Young adults showed similar
hit rates throughout each scenario.
Z150287-8676
Aims
à Attention to a lead vehicle and peripheral localization abilities
were measured in several driving scenarios.
We predict aging adults will switch, or “disengage”, from forward
vehicle monitoring when they must simultaneously prioritize
peripheral information, suggesting serialization of attentional
deployment.