1. Effects of uncertainty, transmission type, driver age and gender on brake reaction and movement time Professor: Liu Students: Ruby

2. Motive & Purpose Motive- 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).

3. 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.

4. 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)

5. 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.

6. 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)

7. 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).

8. 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)

9. Methods-Participants 18-25 12M 6A6M 12F 6A6M 26-49 12M 6A6M 12F 6A6M 50+ 12M 6A6M 12F 6A6M

10. 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.

11. 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.

12. 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.

13. Results The four-way ANOVA on MT yielded two significant 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.

14. Results The four-way ANOVA on RT only 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).

15. Discussion The authors’ finding is opposite that of Olson 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 levels produced higher levels of arousal, which affected MT.

16. 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.

17. 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.