1. Judgments about collision in younger and older drivers Transportation Research Part F 6 (2003) 63–80 學生：董瑩蟬

2. Purpose There were three experiment on this study. The experiment 1 purpose was to investigated that age different in judgments about two objects collide. The experiment 2 was to measure age different when judgments about whether two objects would collide. The experiment 3 investigated the age different in judgments whether the object would hit the observer.

3. Reference Time-to-contact (TTC) judgment that can be used to measure driver licensure. (Schiff & Arnone, 1995) The older adults has underestimated TTC judgment (Hancock & Manser, 1997; Schiff et al.,1992). Some studies found that the older adults were bad judgment abilities. (Fisk & Rogers, 1997; Salthouse, 1982; Sekuler et al.,1982)

4. Method-experiment 1 Participants –Eight young age18 ~ 29 (M=20.25,S.D=3.81) –Eight older age 50~64 (M=55, S.D=5.18) –The young group come from Texas Tech University students Equipment –Pentium ∥ -300 MHz computer –Accelgraphics Accelstar ∥ graphics card –35.56 cm monitor

5. Method-experiment 1 Object –The object move speed was 3 s –The object disappeared when it was 3 or 6 s from virtual contact with the pole. (TTC) –The final distance were near or far from pole. –There were 10 different scenes which include stationary observer or moving observer. (motion condition)

6. Method-experiment 1 Procedure –Participant must to complete train trials. –The viewed distance approximately 45.72 cm. –The participants press a mouse button when they found object. –When the object reach the pole that participants keep moving at the same speed after it disappeared. –TTC was the time between the object’s disappearance and the participant’s response.

7. Method-experiment 2 Participants –Eight young age18 ~ 20 (M=18.63,S.D=0.92) –Eight older age 55~76 (M=62.63, S.D=7.98) Object –There was different cues relative size and ground- intercept information for judgments collide. –The cubes approached for 1s and the cubes angles include 45°, 90 °,or 180 °. –There were half trials, the cubes would collided. –The cubes disappeared before they collided or passed. –There were 36 trials simulated stationary, and 144 trials moving observation.

8. Method-experiment 2 Procedure –The viewed distance approximately 38.1 cm. –The participants respond the cubes collided or not. –When the cubes disappeared that participants keep moving at the same speed. –When ground-intercept information was present that participants were to press the bottoms and respond the tips collide or not. –Participant respond that how much confidence. –This experiment collect the correct.

9. Method-experiment 3 Participants –Eight young age18 ~ 23 (M=20.25,S.D=1.49) –Eight older age 51~75 (M=60.63, S.D=9.71) Object –There were three different dimensional scenes square object. –The object approached to observation plane for 2 s. –When it was either 1.5 or 3s from virtual contact the observation plane, it was disappeared. –There were half trial simulated stationary observation point, and the other was remaining trials. –The subject respond how far the object start to approach. And respond collisions or miss.(PSE)

10. Method-experiment 3 Procedure –The viewed distance approximately 45.72 cm. –The participants respond the object whether hit. –And keep the same speed to moving after the object disappeared. –There were 8 trials. And total need 1 hours.

11. Method Supplementary tests and driving questionnaires –Simple reaction time: the subject press a mouse button when the square present. After the countdown ca 0.5, 2.25, 4.0, 5.75 and 7.5 second. –Mental rotation task: there were three characters F 、 J and L that were rotated 90°, 180° or 270°. Subject respond the character was normal or reversed position. They collect the correct responses.

12. Method Supplementary tests and driving questionnaires –Clock task: there were 20 digital format (e.g.,10:10) present and subject respond the clock angle greater whether more 90°. They collect the correct responses. –Driving questionnaires: The first was driving and accident histories. The second was DBQ include 15 times. (Table 1 and Table 2)

13. Method

15. Result-Age differences in judgments about collision Experiment 1: Judgments about when two objects would collide –The older driver was significant smaller for TTC judgment.( older=2.92, young=4.37) –The 2*2*2*10 (age* TTC* final distance*motion condition) ANOVA result found the older TTC judgments were smaller than younger. (overall means were 3.22 and 4.13)

16. Result-Age differences in judgments about collision Experiment 2: Judgments about whether two objects would collide Fig. 1. Experiment 1. Mean percentage correct as a function of relative cube size, event type, presence/absence of ground-intercept information, and age. Error bars indicate 1 standard error of the mean. The 2*2*2*2*3*5 (age*relative cube size*collision/miss*presence/ab sence of ground-intercept information*approach angle*motion condition) The younger adults mean percentage correct was higher than older adults. (F(1,12)=10.67)(Y=72%, O=59%)

17. Result-Age differences in judgments about collision Experiment 3: Judgments about whether an object would hit the observer Fig. 2. Experiment 2. Mean PSE for horizontal speed as a function of gender and age. Error bars indicate 1 standard error of the mean.

18. Result-Age differences in judgments about collision 2*2 (TTC* motion condition) ANOVA result found the older adult’s mean PSE for horizontal position was high when TTC was 3 s. 2*2*2*2 (age*gender*TTC*motion condition) ANOVA result found the significant age* gender interaction for PSE horizontal speed. (F(1,8)=8.37) see fig 2

19. Result-Correlations with judgments about collision Experiment 1:Judgments about when two objects would collide –There were no significant different between TTC judgments and driver performance measures. Experiment 2: Judgments about whether two objects would collide –There were positive correlation between correct and stooped for the police frequency. (r=0.05) Experiment 3: Judgments about whether an object would hit the observer –There were significant correlation between PSE for horizontal and stooped for the police frequency. (r=- 0.72) in younger adults.

20. Result-Supplementary tests and driver performance measures Age differences –The older has significant lower mean DBQ-V and DBQ-E.

21. Result-Correlations DBQ-E and DBQ-V –Between minor accidents and major accident has significant correlation. (r=0.38) and between minor accidents and DBQ-E has the same result. (r=0.3) –There was significant correlations between minor accidents and major accidents, majior accident and stooped for police frequency for older adults. (r=0.64 and r=0.48)But not for younger drivers. –There was significant correlations between DBQ-V and stooped for police frequency (r=0.46) for younger drivers, and the same between major accidents and speed violations. (r=0.67)

22. Result-Correlations Spatial abilities –The mental rotation and clock related to collision judgments that was not significant. –Between PSE for horizontal position and mental rotation task performance (r=-0.54) –There were significant correlation between reaction time and PSE for both horizontal position (r=0.64) and horizontal speed (r=7.1) –The older adult between DBQ-E and clock task performance has significant correlation (r=-0.47) –There were significant positive correlation between age and reaction time. (r=0.35)

23. Discussion The experiment result found that the older adults has underestimated TTC. This result similar to Hancock & Manser (1997) and Schiff et al. (1992) Older adults may loss some extract information from visual flow (Warran et al.,1989), they relaying more other sources information such as ground- intercept information.

24. Conclusion The older adults has higher reaction time than younger adults. The older TTC judgments were smaller than younger. The younger adults mean percentage correct (collision or miss) was higher than older adults.