Astrid J.A. Lubeck, MSc1 Jelte E. Bos, PhD1,2 John F. Stins, PhD1

1 Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, the Netherlands

2 TNO Perceptual and Cognitive Systems, Soesterberg, the Netherlands

Moving and still images can induce comparable amounts of postural sway,

but different levels of sickness

1

Introduction

Studies about the effect of moving images• General design experiments

1. Pre- and post measurement2. Variables:• Postural Sway• Visually induced motion sickness (VIMS)

3. Exposure to moving images

• Result– Postural sway ↑, VIMS ↑

• Are these results caused by motion?

2

Introduction

Research question and hypothesis

• Research question– Is motion essential for causing an increase in postural sway and

VIMS?

• Hypothesis– Motion does cause an increase in postural sway and VIMS.

• No changes in still images condition.• Changes in moving images condition.

3

Method

Subjects and design

• Subjects– 15 subjects– 6 males, 9 females– Mean (SD) age: 29.5 (5.9) years

• Design– Within subject design– Experimental condition: Moving images– Control condition: Still images– 2 measurements: Pre and post

4

Method

Images

5

Method

Measurements

• Postural sway– Force plate– Normal double stance

• Eyes closed– Duration: 60 seconds– Center of pressure (CoP) data

• Sway path length

• Visually induced motion sickness (VIMS)– Simulator sickness questionnaire (SSQ; Kennedy et al., 1993)– Only total score

6

Results

Total simulator sickness scores

7

Results

Sway path length

8

Discussion

• Postural sway– Increase in SPL after exposure to both moving and still images

• VIMS– Only an increase in VIMS after exposure to moving images

• No difference in postural sway after exposure– Puzzling?

9

Puzzling results?

Discussion

10

2 possible explanations

• Wallpaper illusions – Can cause changes in postural sway (Kelly et al., 2005) – Can cause disorientation (Cohn & Lasley, 1990)

Discussion

Moved by still images

Discussion

Moved by a first person shooter (FPS) game

12

• Vection– Illusion of self-motion

• Do players experience vection or some other sensation?– Images may not contain adequate flow

• Sustained and unidirectional– Other possible mechanisms at work?

Discussion

Vection in FPS games?

Still images can cause an increase in postural sway but only moving images cause motion sickness.

Conclusion

Take home message

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Disclosure of interests

Disclosure