Week 6-2: Virtual Displays & Virtual Environments

1. Week 6-2: Virtual Displays & Virtual Environments

2. Week 6 Topics • Lecture 6-1 • 3D Displays • Navigation & Self-Motion • Lecture 6-2 • A Virtual Display for Speed • Perception of Heading • Perception of Time to passage

3. 36 01 02 03 10 3750 5620 5 -5 -10 Virtual Displays for Speed?

4. Virtual Displays for Speed • Design Features • Flow vectors presented as moving arrows: speed and direction of arrows indicates magnitude and direction of speed error: arrows stop moving if pilot is at the target speed (prevents adaptation) • Overall size of arrows also changes as a function of speed -- arrows disappear if no speed error • size changes in steps: “attention grabbing” • reduces reliance on acceleration detection • Stimulus-Response (SR) compatibility: direction of arrows indicates direction of throttle movement to correct speed

5. Virtual Displays for Speed • Testing the Virtual Display: Cox & Dyre (2000) • Dual Task: fly simulator through “waypoints” while simultaneously maintaining target altitude and speed • Single Tasks: autopilot controls flight-path or speed

6. Virtual Displays for Speed • Measures: • Speed error • Altitude error • Missed waypoints • Subjective workload: NASA-TLX

7. Virtual Displays for Speed • Measures: • Speed error • Altitude error • Missed waypoints • Subjective workload: NASA-TLX

8. Virtual Displays for Speed • Measures: • Speed error • Altitude error • Missed waypoints • Subjective workload: NASA-TLX

9. Perception of Heading • Cues in Optical Flow • Expansion point or focus of radial outflow (Warren et al., 1988) • problem: eye movements • Differential Motion Parallax (Cutting, 1986) • Flow Symmetry (Dyre & Andersen, 1997)

10. Perception of Heading Rotational Flow due to Eye Movement Translational (Optical) Flow Retinal Flow (Translation + Rotation)

11. Perception of Heading • Active closed loop control vs. Passive open-loop judgments • Active controllers (drivers) can perceive heading in a manner fundamentally different than passive viewers (passengers): Dyre, Warren, & Garness (1996) • Controllers -- more global? • Passengers -- more local? • Consistent with active-passive differences for motion sickness and spatial orientation • Armstrong (1939), Reason & Brand (1975) • Larish and Andersen (1995)

12. Perception of Heading • Field of view effects • Central visual field is necessary and sufficient for accurate judgments of heading • Warren & Kurtz (1992), Crowell & Banks (1993), Atchley & Andersen (1999) • Problems • used small fields of view (19” monitor) presented at different retinal eccentricities • controlled fixation • used discrete, open-loop judgments • did not present symmetrical fields of view to periphery

13. p(q, f) f a r H q Perception of Heading: Information Basis

14. Peripheral Vision & Perception of Heading • Richman & Dyre (1999); Dyre, Morrow, and Richman (2000) • Used large, symmetrical fields of view for peripheral stimulation (90 x 34 deg of visual angle) • measured active control performance • free fixation: field of view mask or “porthole” yoked to observer’s gaze direction • Examined both yaw and pitch control

15. Apparatus for Yoking Gaze to Display

16. Central + Peripheral (Full) Visual Field (image contrast inverted)

17. Central Visual Field Condition (image contrast inverted)

18. Peripheral Visual Field Condition (image contrast inverted)

19. Central-Peripheral Visual Fields: Results • Results of • Peripheral visual fields benefit performance • Peripheral vision as good as central vision when peripheral regions of flow are orthogonal to control axis Dyre, Morrow, and Richman (2000)

20. Perception of Time to Contact • Time to Contact • specified by the size of an object scaled by its expansion rate (change in size) • size changes exponentially as an object approaches (object size)/(change in object size) • other factors that influence judgments • object size (large objects appear nearer) • Object expansion rate (dX/dt) • observer motion combined with object motion: lowers time to contact estimates