Effects of uncertainty, transmission type,driver age and gender on brake reaction

and movement time

Professor: Liu

Students: Ruby

Motive & PurposeMotive-

The authors want to know that how does the braking time (BT) change in different age , gender, vehicle transmission type and event uncertainty.

Purpose-To examine the braking time (BT) which is consisted of reaction time (RT) and brake-movement time (MT).

References

• Perception reaction time (RT)-

The time between the light onset and the first movement of the foot on the accelerator.

• Brake-movement time (MT)-

The time from the first movement of foot on the accelerator and the contact with the brake pedal.

References

• In order to shorten RT, the following driver must be able to perceive the brake lights of the lead car as soon as possible.

• The central high-mounted stop light (CHMSL), located in the middle of the rear window, is easy to detect by following car. (McKnight & Shinar, 1992)

References

• RT and MT are influenced by different variables:

1.RT being affected by event uncertainty (Hick, 1952).

2.MT is affected by the distance and accuracy demands of the movement.

References

• The effects of age and driving experience on RT are not clear cut.

1.Braking RT increases with age (0.86 s in 20s to 1.37 s in 50s) (Welford, 1977 )

2.The average RT is only a little longer in some situations for the older drivers (50–84) than the younger drivers (18–40). (Olson and Sivak, 1986)

References

• The sensory-motor skills (reflected in RT) improve with driving experience (Cohen, 1987)

• Older people are susceptible to occasional lapses in visual information processing and yield occasionally very long RTs (Maltz & Shinar, 1999).

References

• Males and females had the same MT when the brake pedal was higher than the accelerator pedal, but females were 25% slower (194 ms compared to 155 ms) when both pedals were at the same level. (Davies & Watts, 1970)

• Road sign detection by novice drivers was poorer while driving with a manual transmission than when driving with an automatic transmission. ( Shinar et al. 1998)

Methods-Participants18-25

12M 12F

6A 6M 6A 6M

26-49

12M 12F

6A 6M 6A 6M

50+

12M 12F

6A 6M 6A 6M

Methods-Procedure• Three uncertainty conditions:

1.10 fixed intervals of 2 s.

2.10 variable intervals of 2, 4, 6, 8 and 10.

3. 10 vary intervals of 2, 4, 6, 8, 10 and none.

• There was a different random for every tester.

Results

• The ANOVA showed a significant learning effect (trials) on MT only. Therefore using a Post Hoc Scheffe test conducted on the 10 trials showed that the learning was limited to the MT of Trial 1.

Results

1. RT is increased with uncertainty, while MT actually decreased lightly with event uncertainty.

2. The Post Hoc Scheffe test analysis for a. RT showed that all three levels of uncertainty were significantly different from each other ( P < .05).

b. MT showed that only the lowest and highest levels of uncertainty were significantly (P= .048) different from each other.

Results• The four-way ANOVA on MT yielded two signif

icant main effects—gender and uncertainty and 1 three-way significant effect—age, transmission, and uncertainty.

1.MTs were longer with the low event

uncertainty than with the higher levels of event

uncertainty.

2. Males had lightly shorter MTs than females

[F(1,60) = 5.24, P= .026]; 0.16 s vs. 0.19 s.

Results• The four-way ANOVA on RT o

nly two significant main effects—age and uncertainty.

The effect of age on RT [F(2,60) = 6.20, P= .003]

• The Post Hoc Scheffe test showed that only the young group and the older group were significantly different from each other (P= .003).

Discussion• The authors’ finding is opposite that of Ols

on and Sivak (1986) who found that MT increased with reduced expectancy.

• Two explanations for the reason:1. The first is that compensating for long RTs

with short MTs. 2. The second is that the higher uncertainty le

vels produced higher levels of arousal, which affected MT.

Discussion

• Male MTs were shorter than female MTs (17 ms compared to 18 ms). Due to the fact that females may have less real driving experience compared to males or it could be due to a physical factor, such as greater muscle strength of males.

Discussion

• The RT increases with age, devices designed to shorten the RT through early warning may have more impact on preventing rear-end collisions in following cars driven by elderly drivers.