Harpreet Kour et al, J Biosci Tech,Vol 4(1),2013, 508- 512
ISSN: 0976-0172
Journal of Bioscience And Technology
www.jbstonline.com
ASSESSMENT OF AUDIO-VISUAL REACTION TIME IN DRIVERS
Harpreet Kour
Dept of Physiology, J.N.Medical College, Belgaum. Karnataka, India
Email: [email protected]
Abstract:
Background: The quickness in any work in our life relates to the speed with which
body react to external stimuli. It is very essential in occupation like driving, in which
quicker level of response is one of measure by which number of road traffic
accidents can be reduced. Assessment of audio-visual reaction time can be an
important test for drivers.Objectives: 1. To compare auditory and visual reaction
time to different stimuli in Drivers and Normal controls. 2. To find out difference
between auditory and visual reaction time in Drivers. Methods: 50 Drivers and 50
age and sex matched were enrolled into two groups as per inclusion criteria. A
through clinical examination was done. A self-administered questionnaire to record
personal data was given. Results: Auditory and visual reaction time of Drivers is
shorter than that of healthy controls. On comparison, auditory reaction time is greater
than visual reaction time. Conclusion: Reaction time makes important test for
assessment of quickness & coordination of visual and auditory responses, which
plays utmost important role in driving to reduce the road traffic accidents.
1. INTRODUCTION:
Every single action we make is an
amendment or reaction to some ailment or
stimulus either in biosphere about us or in
our individual body. Our emotions,
attention, memories these and all added
reaction we make are responses to stimuli
which play upon us1.
In day to day life, a modern man has to
respond often to numerous diverse situations
often instantaneously if one has to survive.
For, example an automobile driver applying
brakes in a fraction of second or for a
factory worker on machine, quick
maneuvering is must and may be lifesaving.
In case of drivers, quicker level of response
is one of the very important measure by
which the number of accidents can be
reduced2.
Audio-Visual reaction time is the speed,
with which an individual can respond to an
auditory stimulus and visual stimulus
respectively3.
It
has
physiological
significance and is a simple and non invasive assessment for peripheral and
central neural structures4.
Reaction time is decisive for our everyday
lives and needs intact sensory skills,
cognitive
processing
and
motor
performance. It determines the alertness of a
person because how quickly a person
responds to a stimulus depends on his
reaction time and therefore it must be lesser
in certain occupation e.g. Drivers,
sportsmen, pilots, military people, doctors,
nursing staff, security guards. Various
factors influencing human reaction time are
age, left or right hand, direct (central) versus
peripheral vision, practice, fatigue, fasting,
breathing cycle, personality types, exercise,
and intelligence of the subject5.
The single cause of road traffic injuries in
57% is by human factor, and together with
other factors in more than 90% of all road
traffic accidents. Human factor comprises
numerous aspects, where reaction time is
very important 6.There are abundant studies
conducted on Audio-visual reaction time in
healthy subjects, in different age groups, in
athletes and other sports, smokers, tobacco
Chewers, etc. But study on in case of drivers
regarding Audio-Visual reaction time
508 Harpreet Kour et al, J Biosci Tech,Vol 4(1),2013, 508- 512
appears to be meager. The present study was
carried out keeping in view the AuditoryVisual reaction is an utmost important test
for the drivers. The impact of Audio- Visual
reaction time can be taken as a preventive
measure for Road traffic accidents, as this
test is important for assessment of quickness
& coordination of visual and auditory
responses. In drivers, number of accidents
can be reduced by measuring quicker level
of response with aid of audio-visual
analyzer.
2. MATERIALS & METHODS:
The study protocol was prepared and
approval was taken from the Institutional
Ethical committee. This is comparative
study where 50 Drivers and 50 age and sex
matched controlled were enrolled into two
groups as per inclusion criteria. A through
clinical examination was done. A selfadministered questionnaire to record
personal data was given.
Inclusion criteria:
1. All subjects were taken from KSRTC,
Belgaum.
2. All the subjects included were healthy,
nonalcoholic, nonsmokers or nontobacco chewer.
3. All the subjects with no auditory or
visual disturbances.
Exclusion criteria:
1. Alcoholics, smokers or with auditory or
visual disturbances.
2. Suffering from any chronic disease.
The subjects were instructed about the study
protocol and informed consent was obtained
from them.
The apparatus used in this study was the
portable research reaction timer with two
response choices latest manufactured in
March 2010 and was purchased from Anand
ISSN: 0976-0172
Journal of Bioscience And Technology
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agencies, Pune, which can measure VRT
and ART.
Specifications of reaction timer:
1. Inbuilt chronoscope – 4 digit chronoscope
with least count of 1/1000 seconds.
2. It works on – 230 volts AC.
Each subject was made acquainted with the
apparatus and the procedure to alleviate any
fear or apprehension. ART and VRT were
measured in a quiet room. The tests were
done with the subject sitting comfortably in
a chair. ART and VRT were measured by
reaction time instrument. Accuracy of this
instrument is ± one digit. All the subjects
were right handers and used their right hand
to press the switch to stop the quartz clock
of the apparatus. From the auto-display
reaction time was noted7.
1. Auditory Reaction time- by AudioVisual Analyzer
2. Visual Reaction time- by Audio-Visual
Analyzer
Subjects were presented randomly with 2
visual stimuli i.e. red & green light and 2
auditory stimuli i.e. high pitch and low pitch
sound stimuli. Three readings of each
stimulus were noted after giving three
practical trials and the lowest was taken as
the reaction time8-10
3. RESULTS:
The results were expressed as mean ± S.D.
The statistical difference was determined by
‘Z’ test and results were analyzed by ‘z’ test
and student t test. The auditory reaction time
for both click and tone was significantly
higher in group B than in group A in this
study. The visual reaction time for all the
four colors i.e., white, red , yellow and green
was significantly higher in group B than in
group A.
509 Harpreet Kour et al, J Biosci Tech,Vol 4(1),2013, 508- 512
ISSN: 0976-0172
Journal of Bioscience And Technology
www.jbstonline.com
Table:
Comparison of Reaction time b/w Drivers & normal controls:
Auditory
Visual
Drivers
(Group A)
180.5±34.02
177±28.54
190.1±27.80
191.1±34.83
185.9±28.10
181.5±32.13
click
tone
white
Red
yellow
Green
Controls
(Group B)
264.9±47.58
277.9±55.89
281.7±54.19
272±53.26
266.7±48.03
269.3±46.80
P-values
t
p
8.038
0.000*
8.954
0.000*
8.372
0.000*
7.077
0.000*
8.085
0.000*
8.661
0.000*
(*) p value significance<0.05
Graph:
Showing difference between auditory and visual reaction time in Drivers
Differences with ART and VRT in Drivers
195
190
185
180
175
170
click
Tone
white
ART
red
yellow
green
VRT
Series1
Reaction time- auditory and visual both were
significantly high in drivers than in the
controls. On comparison between Auditory
reaction time is greater than visual reaction
time.
4. DISCUSSION:
Reaction time is the interval between the
onset of a stimulus and the commencement of
a movement response (Magill 1998) 11.
Normal reaction time for a visual stimulus is
around 250 ms and for an auditory stimulus
is around 170ms (Magill 1998) 11. Reaction
time can be further broken down into three
parts. The first part is perception time - the
time for the application and perception of the
stimulus and giving the essential reaction to
it. The second part is decision time, which
signifies the time for giving a suitable
response to the stimulus. The third part is
motor time, which is the time for compliance
to the order received (Tripo 1965) 12. Singer
et al. (1993) defined reaction time as being
composed of four stages, namely: the start of
Eye movements, eye movement time,
decision time and muscle contraction time13.
510 Harpreet Kour et al, J Biosci Tech,Vol 4(1),2013, 508- 512
Escalations in reaction time can lead to safety
risks on the road. In circumstances such as
the braking response, the reaction time of the
driver is not simply a one step process, but
rather a sequence of complex reactions. The
braking response involves mental processing
time, movement time, by which the muscles
will respond to the action potentials, sent
from the central nervous system. The ability
to carry out muscular movements can be
dependent on the situation14.The final
segment of the reaction is the device response
time which refers to the time it takes the
mechanical device to engage and perform the
desired action, such as the time lapse from
the time the brakes are applied to when the
car comes to a halt. Movement and device
response times will remain fairly predictable
from one person to another when using the
same device in similar situations15. Vision is
the most important sense for safe driving.
Studies suggest up to 80% of all crashes
can be avoided with better vision skills.
About 90% of the information we use when
driving is gathered by our vision. Other
senses such as hearing, touch, feel, balance
and smell provide the remaining information.
We have the widest range of vision (largest
visual field) when stationary. Typically our
primary vision is within 10° - 12° of our line
of sight. But objects can be detected outside
of this in our peripheral vision, 90° to the left
and right, 60° above and 70° below our line
of sight. This means when stationary we have
a 180° horizontal visual field and a 130°
vertical visual field16.
At speed however our vision focuses
automatically further ahead and thus the
visual field reduces in all directions. At 100
km/h our horizontal visual field is only 40°
(20° to the left and right of our line of sight).
Outside of the visual field we need stimulus
to make us turn our head and look in that
direction. A good stimulus could be
movement relative to the background or a
ISSN: 0976-0172
Journal of Bioscience And Technology
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flashing or pulsating light or some other
bright light. This is one reason why our
indicator lights flash, so they can be noticed
and seen by other drivers even outside of
their field of vision. This is also a good case
for the use of daytime running lights on
vehicles, especially when driving at high
speeds to make sure your being seen by other
drivers16-17. That’s why a lot of distractions
are everyday life and they can be proving
deadly while driving.
In our study, difference with auditory and
visual reaction time of Drivers is shorter than
that of healthy controls, which is of utmost
significance.
In present study we also compare auditory
and visual reaction time and found auditory
reaction time is lesser than that of visual
reaction time. This can be explained by
mechanism of sound entering the ear which
can reach appropriate receptors with
particular no loss of time. For visual reaction
time the rods and cones are not excited by
light
directly
and
the
intervening
photochemical process takes appreciable
time2.
5. CONCLUSION:
Our finding could explain shorter auditory
and visual reaction time in the drivers makes
most important sense for safe driving.
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