Psyc 736- Graduate Seminar: Eye-tracking Theory and Application

1. Psyc 736- Graduate Seminar: Eye-tracking Theory and Application Driving Related Eye-Tracking Review: Straight and Curved Roads By: Jess Gilland

2. OverviewThe majority of literature from the driving domain centers around these main areas of focus… • Straight road driving • Curved road driving • Visibility Factors • Preview Time and Sign Reading • Experience • Scene Complexity • Visual Flow and Heading Determination • Fatigue • Speed • Age • Workload Of these topics, I will focus my review on a few key studies dealing with actual eye-tracking on straight and curved roads. (most note changes, but few actually look at eyes)

3. Straight Road Driving • General summary figure you will see was taken from Serafin (1994) review section, but the actual paper’s results will not be discussed until curve section. • -Mourant, R., & Rockwell, T. (1970) Mapping eye movement patterns to the visual scene in deriving: an exploratory study. Human Factors, 12 (1), 81-87. • -Bhise, V. & Rockwell, T. (1973). Development of a methodology for evaluating road signs. Project EES-315B Final Report. Engineering Experiment Station Bulletin 207. Engineering Publications, College of Engineering, The Ohio State University, 2070 Neil Avenue, Columbus, OH 43210. (241 pp.) • - Taoka, G. (1991) Distribution of driver spare glance durations. Transportation Research Record 1318, 142-146.

4. Serafin, C. (1994) This paper sought to describe curve navigation characteristics by age, but also gave a very good series of graphics summating some findings from a few other studies. • A few things to note in the next slide are that…. • On straight roads, the majority of time is spent monitoring directed down the road in projected path of car • Fixation time is also biased towards objects on the right hand side of the road* • *This changes as a function of distance with “ “scanning by side” leveling out as you get closer to vehicle and even becoming more biased to left side for things like edge markers as reported in the Blaauw (1975) study.

5. Serafin (1994)

6. Mourant, R., & Rockwell, T. (1970) • Used 8 young male subjects • Actual driving conditions (navigate a stretch of highway at 50mph in a 63’ Chevy) • Used corneal eye-marker camera to extrapolate fixation positions (accurate to within ±1/2° horizontal and ±1° vertical) • 6 trials, 2 routes, recorded 180-200 seconds of data during each

7. Mourant, R., & Rockwell, T. (1970) • noted fixation pattern change due to learning usually evident after 3rd trial (see example) • down and left shift • Majority of fixations were directed to signs, cars, markers, and other potential hazards (“where there was information”) • Fixations were biased toward the right side of the road.

8. Mourant, R., & Rockwell, T. (1970) • Fixations also became very ordered when involved in a car following task. • decreased mean number of fixations per minute from 221 to 196 • biased them towards the lead car (76.7 of the 196 were dedicated to the lead car) BEEP!!

9. Bhise, V. & Rockwell, T. (1973) • Naturalistic study, simply asked to navigate a stretch of freeway with no secondary task. • Subjects did not know they were being studied for sign reading behaviors. • Large study comprised of 8 smaller studies each using 3-5 subjects • Looked at sign recognition (visual, not verbal) • specifically, how much time needed to be dedicated to a sign in order to interpret it • determined “interpretation” of a sign by the frequency and time spent on its fixation. (relies on the idea that once information is processed, it will not need to be revisited) • Changed the message on both task relevant (road navigation aides) and irrelevant signs to observe fixation durations. • Evaluated over 400 different highway signs during daylight conditions

10. Bhise, V. & Rockwell, T. (1973) • In control experiments, normal signs were usually fixated only once and very briefly • Observed that this initial fixation duration increased as cognitive demands increased. • These demands could be correlated to... • -high traffic density - length of message • -unfamiliar road - familiarity of sign • -poor sign legibility - relevancy of message

11. Bhise, V. & Rockwell, T. (1973) • Concluded that… • Drivers time-share with the sign and the road and this becomes disproportionate as demands increase. • The time-distance for first fixation of sign is the “key” variable for evaluating design as the less efficient designs caused decreased interpretation/recognition distances (they didn’t look at the sign until they were close to it) • When in unfamiliar, confusing conditions or viewing inadequate signs…. • sign reading is typically started late • attention devoted to sign is disproportionately high • there will be late interpretation of signs, often AFTER the sign had been passed.

12. Taoka, G. (1991) • Short general theory paper • Analyzed glances from several studies to determine how fixation duration interacted with the loading produced by a task. • Concluded that people have the longest fixation durations for goals that require the most brain computational power ( i.e. require interpretation). • Temp gauges, traffic signs, heading determination • The least amount of fixation time was spent on update activities • mirrors, speedometer • Ultimately concluded that people dedicate the most cognitive and visual resources to stimuli that “mean something” within a given context.

13. Curved Road Driving • Again, I will start with Serafin (1994) summary figures to lead into the review. • - Shinar, D., McDowell, E., & Rockwell, T.(1977) Eye movements in curve negotiation. Human Factors, 19, 63-71. • -Olson, P., Battle, D., & Aoki, T. (1989) Driver eye fixations under different operating conditions. UMTRI-89-03 • -Land, M., & Lee (1994) Where we look when we steer. Nature, 369, 742-744. • -Serafin, C. (1994) Driver eye fixations on rural Roads: insight into safe driving behavior. Technical report UMTRI-94-21 • -Land, M., & Horwood, J. (1996). The relationship between head and eye movements during driving. In Gale, A.G. et al. (eds.), Vision in Vehicles V., Elsevier Science Publishers, 153-160. • -Dishart, D., & Land, L. (1998) The development of eye movement strategies of learner drivers. In G. Underwood (eds), Eye Guidance in Reading and Scene Perception, Elsevier Science Publishers, 419-429. • -Land, M.F., & Tatler, B.W. (2001). Steering with the head: the visual strategy of a racing driver. Current

14. Serafin, C. (1994)Right Curves • In the next figure you will two main trends • The majority of fixations are biased to right side. • The time spent scanning is also biased to right side • Time is further refined to mainly be directed towards inside edge line(tangent point) or at the road itself

15. Serafin (1994)

16. Serafin, C. (1994)Left Curves • In the next figure you will again notice some trends • The majority of fixations are now biased to the left side, however not to the same degree as they where when turning right. • The time spent scanning is also biased to left side side, but again is now more spread out along the horizontal axis especially becoming noticeable as one gets closer to the car. • Again, time can be further refined to be mainly directed towards inside edge line(tangent point) although in a left curve there begins to be an increased number of fixations dedicated towards the eventual car’s path leading out of the curve as well (27% fixation on left curve vs only 18% in a right curve)

17. Serafin (1994)

18. Shinar, D., McDowell, E., & Rockwell, T.(1977) • Observed the fixations of 5 subjects (paid big money: $3/hour) as they navigated a 2 lane rural road. • Looked at 46 individual road sections each classified as either a… • curve • approach • or • straight road • Measured data with a head mounted corneal reflection eye-tracker and superimposed the fixation point onto a visual image taken with a camera also mounted on helmet.

19. Shinar, D., McDowell, E., & Rockwell, T.(1977) • Main observations • Fixation patterns seem to follow the geometry of the road, especially on curves • On straight roads, fixations tend to be less active and focus mainly on area of expansion. • Curve navigation relies more on direct foveal cues than peripheral. • Subjects begin searching for anticipated trajectory several second BEFORE the curve occurs. • Searches to the left and right are not symmetrical in curves • more looks to the right when turning right than the left when turning left.

20. Olson, P., Battle, D., & Aoki, T. (1989) • Study designed to observe fixations on the road during a car following task. • Used a “single corneal” reflection head mounted eye tracker (similar to ours) • 6 subjects (all male, 20-34) • 7 independent variables (12 possible conditions) • Night/Day (2) • Following/No following (2) • Left/Right curve or Straight (3) • Dependent variable was fixation duration and total time of fixation on a target.

21. Olson, P., Battle, D., & Aoki, T. (1989) • Concluded that … • eye fixations on straight roads follow uniform scanning pattern. • Fixations tended to be oriented towards the direction of travel when turning • At night fixations seemed to be centered around where the headlights illuminated • Fixation dwell times tended to be longer at night • ## When a lead vehicle is present, it dominates the attention of drivers, especially at night or on straight roads.## • See next three slides for graphs of fixation trends.

22. Olson, P., Battle, D., & Aoki, T. (1989)

23. Olson, P., Battle, D., & Aoki, T. (1989)

24. Olson, P., Battle, D., & Aoki, T. (1989)

25. Land, M., & Lee (1994)Land, M., & Horwood, J. (1996). These two sister studies sought to discern how the head plays a role in curve navigation. In the (1994) paper they concluded that a driver seeks out a tangent point when navigating a turn and will seek out this tangent point throughout the maneuver as a sort of orienting strategy.

26. Land, M., & Lee (1994)Land, M., & Horwood, J. (1996). • In the (1996) paper they went slightly further and noted that there seemed to be three main coordinated head/eye phases when navigating a curve • Phase 1# The eyes seek out the curve, but no head movement occurs

27. Land, M., & Lee (1994)Land, M., & Horwood, J. (1996). • Phase 2# After noticing the curve, the subjects begins to align the head in a such a way as to point the eyes into the curve and away from current vehicle heading.

28. Land, M., & Lee (1994)Land, M., & Horwood, J. (1996). • Phase 3# Starting about halfway through the curve in anticipation of an exit, the eye locks onto a distant target and the head counter-rotates with the cars movement to gradually become back in alignment with the cars heading once out of the curve.

29. Land, M., & Lee (1994)Land, M., & Horwood, J. (1996). • These phases were observed in ALL curve situations in this study • regular curves • intersections

30. Serafin, C. (1994) • We viewed the Serafin review sections, now we will talk about the study itself. • This study sought to view differences of age on curve navigation. • 32 participants (16 younger than 35, 16 older than 65) • Used actual driving results at an enclosed 2 lane track.

31. Serafin, C. (1994) • Observed that in general all subjects tended to… • look at right scenery more on straight roads verses curved roads. • Exhibit more fixations on curved roads than straight roads • and • Everyone attempted to maintain focus near the area of visual expansion when possible

32. Serafin, C. (1994) • When age was contrasted it was observed that… • younger has fewer (30) and longer fixation(174ms) than an older subject(36, 145ms), BUT the locations of these fixation was NOT significant by age. • Concluded that more fixations were needed to compensate for a decreased UFOV in the elderly but this strategy shift did not influence where a subject was going to look. They still looked in the same areas that generally contained the most visual complexity.

33. Dishart, D., & Land, L. (1998) Dishart and Land is one of the two papers I will discuss dealing with curves navigation and experience. • This study observed that… • initial runs (novice) seemed to elicit an increased use of tangent point looks as compared to the experienced group. • Experienced drivers tended to use more peripheral cues to maintain lane performance through a curve • They reasoned that since the experienced driver had a more complex model in his mind so therefor did not need to rely on foveal cues to know what was coming up in the roadway. • This brought about the next study in 2001 using an even “more experienced driver”- racer drivers.

34. Land, M.F., & Tatler, B.W. (2001). This study looked at the eye-movements of a high speed race car driver as he navigated a well known course. They observed that the driver spent the majority of time looking near but not at the tangent point of a curve. Again they concluded that the driver had such a complete model of the track in his mind, that he didn’t rely strictly on foveal cues to guide curve navigation, but was instead allowed to monitor other more important things like other cars while maintaining positioning with peripheral cues.

35. Summary • Straight Road Driving… • Fixations are biased to right side of road even though the overall majority will be directed to the projected path of the vehicle. • Usually centered near point of expansion • This bias also seems dependent on the distance with more leveling out of fixation placement as you get nearer to the car • When following a car, it will dominate the scanning and placement of fixations (effect can be increased even more at night) • People will devote the most attention to areas that contain the most visual complexity or information. (proposed reason for night-time influence, simply isn't any other targets visible)

36. Summary • Curved road driving… • Fixation placement is biased to the direction you are turning, usually toward a tangent point in the road. • This bias is not proportionate to the curve type as there seems to be an increased use of right looks when turning right than left looks when turning left. • This is highly dependent on experience and familiarity with the road. This lessens the cognitive load and allows one to switch from foveal lane maintenance to peripheral lane maintenance. • This projected tangent point is sought out several seconds before you even reach the curve. • Fixations tend to follow the geometry of the curve.

37. Summary • Curved road driving continued… • Curve navigation can be considered to occur in 3 phases • acquisition of curve • readjustment of head/eye fixations to navigate the curve • realignment of head eyes to new projected path exiting the curve • Fixation on curves is similar to straight road driving when… • following another car • under night time conditions (fixations limited to areas illuminated by headlights)

38. THE END Any Questions?????