Field dependence and driver visual search behavior

Professor: Liu

Student: Ruby

Objective

• To investigate the field dependence driver’ visual search behavior on different road and time of day.

References

• Goodenough, 1976– Field dependence drivers were related to acc

idents.– Field independence drivers may avoid accid

ents.

References

• Kaluger and Smith, 1970; Mourant and Rockwell, 1972; Zell, 1969:– This is an relationship between eye moveme

nt and the driver performance which were field dependence/ independence.

Experiment 1: eye movements in curve negotiation

• Purpose– To identify the perceptual search method

involved in curve through and try to get the curves’ accident rate.

• Hypothesis– The field dependent drivers have the less

efficient, and the visual search may be focused on less informative information.

Experiment 1: eye movements in curve negotiation

• Participants– 5 students. (3 male and 2 female)

• Equipment– Eye tracking and experimental vehicle.

• Procedure– Two lane highways in the country view.– 22 curved road and two straight road.– Keep an mean speed on 96 km/h.

Results and discussion

• The embedded figure test– Two females got 15 s and 22s– Three males got 27 s, 40 s, and 50 s.

• Two females and one male can be considered field independent.

Results and discussion

Results and discussion

• The EFT scores and the mean to peak power ration was 0.99.– The more field dependence drivers were more

focused in a small part on the visual field.

• The EFT scores and the median frequency was -0.91.– The field dependence drivers had the slow visual

search which they need more time to search the traffic environment.

Results and discussion

• The field dependence drivers may have a slight tunnel vision or the peripheral vision capabilities may decrease.

• The field dependence drivers were hard to pass the curve road which because their perceptual load is increased.

Experiment 2 : age related changes in drivers’ spare visual capacity

• Purpose– To identify the age related participants’

information processing and the visual search behavior.

Experiment 2 : age related changes in drivers’ spare visual capacity

• Participants– 6 younger people (ages 20-25)– 9 older people (ages 63-70)

• Equipments– The same equipments as in experiment 1.

Experiment 2 : age related changes in drivers’ spare visual capacity

• Six information processing tests– Embedded figure test– Choice reaction time test– Visual search test– A sequential choice reaction test– A memory test– A movement-time test

• Four driving tasks– Driving at normal speed in the clear traffic.

(daytime and nighttime)– Car following at 80km/h.

(daytime and nighttime)

Results and discussion

• In the information processing test, only EFT and the visual search test were significant (r = 0.56) and related with driving visual search.

• EFT– The young drivers were field independent

drivers, they took 0.2 min finished the test.– The older drivers were field dependence

drivers, they took 1.3 min finished the test.

Results and discussion

• Mean visual search time– Younger drivers were 3.2 s.– Older drivers were 2.3 s.

• Mean eyes open time– Younger drivers were 0.7 s.– Older drivers were 1.5 s.

Results and discussion

• When driver had longer meant time, they have to keep his eye open on the road.– The longer time to locate the simple figure

from the complex figure in EFT.

Conclusions

• The field dependence drivers took long time to get relevant information and they were hard to shift their attention to another place.

• The field dependence drivers were hard to get the important information from the road environment and they may have an higher accident.