Effects of viewing conditions on fatigue caused by watching 3DTV Toshiya Morita Hiroshi Ando National Institute of Information and Communications Technology

Background •  Commercially available three-dimensional television (3DTV) is becoming popular. •  The case that people watch 3DTV for relatively long periods of time at home is increasing. •  3DTV manufacturers, 3D contents producers and broadcasters are concerned about the influence of watching 3DTV on viewers. •  However, data remain insufficient on the safety of watching 3D programs with commercially available 3DTVs in typical home-viewing environments. © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Differences between Theatre and home VS

Theatre

Home

Long

Viewing distance

Short

Large

Screen Size

Small

Dark

Environmental illuminance

Light

Assigned area by seat layout

Viewing Position

Relatively free position © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Purpose •  Evaluate the fatigue caused by watching 3DTV under conditions that resemble typical viewing situations at home •  Collect and provide reliable safety assessment data to contribute to the promotion of 3DTV and the realization of human-friendly 3DTV

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Overview of the Experiment •  From January to March 2011 •  500 adult participants •  Evaluate fatigue after watching 3DTV for one hour by objective and subjective indexes of fatigue •  Use commercially available 46 to 50-inch 3DTV that require shutter glasses •  Viewers watch 3DTV from four different positions at relatively light room

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Viewing Condition 3D40

3DTV

3H 3D2H 40 degrees

2DNG 2DWG 3D3H

Peak luminance of 3DTV: Environmental illuminance:

3D5H

100cd/m2 200 lux

2DNG : watch 2D programs without 3D glasses 2DWG : watch 2D programs with 3D glasses 3D2H : watch 3D programs in front of 3DTV at 2H distance

2H

3D3H : watch 3D programs in front of 3DTV at 3H distance 3H

3D5H : watch 3D programs in front of 3DTV at 5H distance 5H

3D40 : watch 3D programs in oblique position of 40 degrees * 2DNG and 2DWG were set as control condition

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Contents of 3D programs Order Genre

Duration (mm:ss)

1

Introduction of historic and sightseeing spots in Sydney, Australia

16:36

2

Soccer match

11:44

3

Classical music clip

6:24

4

Japanese festival

1:20

5

Clay animation

9:14

6

Japanese pop music clip

6:20

7

Documentary about Hiroshima Peace Memorial

11:22

Total 1:03:00 © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Contents of 3D programs •  The binocular disparities of the 3D programs were generally less than one degree at the standard viewing distance •  Five scenes had maximum disparities that exceeded one degree and their total durations were 39 seconds •  The duration of the longest scene whose disparity exceeded one degree was 15 seconds •  3D programs were played with hard disk recorders as 3DTV format referred to as Side-by-Side •  For 2D programs, the right images of the 3D programs were replaced by the left images

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Number of participants 2DNG 2DWG 3D2H 3D3H 3D40 3D5H Total F1 10 10 10 10 10 10 60 F2 10 10 10 10 11 10 61 F3 11 10 10 10 10 10 61 F4 11 12 11 10 10 10 64 M1 10 10 10 10 10 11 61 M2 10 10 10 11 11 10 62 M3 10 11 11 11 11 11 65 M4 12 12 10 11 10 11 66 Total 84 85 82 83 83 83 500 F1: 20 to 29 year-old females F2: 30 to 45 year-old females F3: 46 to 59 year-old females F4: 60 to 69 year-old females

M1: 20 to 29 year-old males M2: 30 to 45 year-old males M3: 46 to 59 year-old males M4: 60 to 69 year-old males © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Evaluation indexes of fatigue •  Objective indexes –  Visual Acuity –  Critical Flicker Frequency (CFF) –  Advanced Trail Making Test (ATMT) •  Subjective indexes –  Simulator Sickness Questionnaire (SSQ) –  Visual Analogue Scale (VAS) •  Additional evaluation –  Questionnaire about physical condition after experiment

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Advanced Trail Making Test (ATMT)

9.0 8.0 Response Time (sec)

•  Circles numbered from 1 to 25 are placed randomly on the display •  Participants are required to use a computer mouse to click these circles in sequence •  Increase in the average response time and the increasing rate of response time indicate decline of visual and cognitive functions due to fatigue

7.0 6.0

Regression line of response time

5.0 4.0 3.0 2.0 1.0 0.0 1 2 3 4 5 6 7 8 9 10111213141516171819202122232425 Number of trials © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Simulator Sickness Questionnaire (SSQ) 16 questionnaire items n  n  n  n  n  n  n  n 

General discomfort Fatigue Headache Eyestrain Difficulty focusing Increased salivation Sweating Nausea

n  n  n  n  n  n  n  n 

SSQ scores

Difficulty concentrating Fullness of head Blurred vision Calculations Dizzy (eyes open) Dizzy (eyes closed) Vertigo Stomach awareness Burping

* Participants answer the degree of symptom with four-point-scale (none, slight, moderate, severe)

u Total Sickness Score u Nausea Subscale Score u Oculomotor Subscale Score u Disorientation Subscale Score

The scores of SSQ, which is the index of motion sickness originally, were used as the index of fatigue because of the similarity of their symptoms.

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Visual Analogue Scale (VAS) •  Participants indicate the degree of fatigue with cross mark on a simple visual analogue scale referring to the feelings that are shown at both ends •  The distance from the left end to the cross mark is used as the score of VAS, ranging from 0 to 100. The best feeling without any fatigue you have felt so far

The worst feeling of fatigue you have never felt so far

Score of VAS 100 mm © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Procedure Informed

Evaluation of fatigue

consent by subjective indexes

Evaluation of fatigue

by subjective indexes

Watch seven kinds of 2D/3D programs

Questionnaire on

physical condition ・・・

・・・・・・ Measurement of

Evaluation of fatigue

Pupil Distance

by objective indexes and Stereoacuity

Evaluation of fatigue

by VAS in the intervals

of programs

Evaluation of fatigue

by objective indexes

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Participant characteristics Experience of watching 3D images Never 21%

Often 3%

Occasionally 58%

Experience of fatigue caused by watching 3D images Always 2%

Sometimes 18%

Occasionally 46% Never 52%

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Participant characteristics Error bar: 95% CI

Stereoacuity

p < .001

11.8%

2.0% Nomal Weak None

86.2%

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Analysis method of effects of viewing condition on fatigue •  The mean values of difference between before and after watching 3DTV in all fatigue indexes are obtained for each viewing condition •  Two-way ANOVA and Multiple Comparison tests are conducted to determine whether these values show significant differences between viewing conditions for each fatigue index.

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Results of objective indexes •  The differences of all objective indexes (Visual acuity, CFF, and ATMT) were very small in all the viewing condition •  Two-way ANOVA demonstrated that the main effect of the viewing condition was not significant for all the objective indexes

No differences between viewing conditions in the decline of visual and cognitive functions due to fatigue

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Results of subjective indexes (SSQ) p < 0.1 p < 0.05

Error bar: 95% CI

No main effect of the viewing condition

p < 0.1

Error bar: 95% CI

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Results of subjective indexes (SSQ) p < 0.01 , p < 0.05 p < 0.1 p < 0.05

p < 0.01, p < 0.05 p < 0.1

Error bar: 95% CI

Error bar: 95% CI

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Results of subjective indexes (VAS) p < 0.05

Error bar: 95% CI

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Results of subjective indexes •  The differences between the subjective indexes before and after watching 3DTV were increased in all the viewing conditions, except 2DNG •  Two-way ANOVA demonstrated that the main effect of the viewing condition was significant for the Total Score, the Oculomotor, the Disorientation of SSQ, and VAS. •  There were significant or marginally differences between 2DNG and the other viewing conditions in these indexes •  There were no significant differences between viewing conditions in which participant watch 2D or 3D programs with shutter glasses •  There were differences in the sensation of fatigue between watching 3DTV and traditional TV •  These differences may not be attributed to watching 3D content, but to wearing the 3D shutter glasses © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Questionnaire results about physical conditions Percentage of participants who reported poor physical condition

10%

The experiment day The experiment day and the follwing day

8%

6%

4%

2%

0% 2DNG

2DWG

3D2H 3D3H Viewing condition

3D40

3D5H

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Total Score of SSQ for the group of participants who reported poor physical conditions Error bar: 95% CI P < 0.001

© 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Results of Questionnaire about physical conditions •  The ratio of participants who reported poor physical conditions in 3D2H is higher than in other viewing conditions. •  There were significant differences between the group of participants who reported a poor physical condition on the experiment day and those who did not report for Total Score, Oculomotor, Nausea and the Disorientation of SSQ.

The sensation of fatigue may be present until the next day if 3DTV is watched at a distance closer than the standard viewing position © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Conclusion •  There was no difference between watching 3DTV and traditional TV in the degree of the decline of visual and cognitive functions due to fatigue. •  There were differences in the sensation of fatigue between watching 3DTV and traditional TV. However, these differences may not be attributed to watching 3D content, but to wearing the 3D shutter glasses. •  The sensation of fatigue may be present until the next day if 3DTV is watched at a distance closer than the standard viewing position. © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

Note •  The results were obtained under conditions that closely resemble typical viewing situations at home, where the participants simply watched 3D programs whose binocular disparities were relatively small on commercially available 46 to 50-inch 3DTVs. •  Therefore, these findings may not fully apply to other viewing conditions and more 3D content that have large disparities. This experiment was done under the auspices of the 3D image evaluation committee of the Ultra-Realistic Communication Forum (URCF). © 2012 SMPTE · e 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

SMPTE Meeting Presentation

Effects of Viewing Conditions on Fatigue Caused by Watching 3DTV Toshiya Morita, Research Expert National Institute of Information and Communications Technology, 2-2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0288 Japan, [email protected]

Hiroshi Ando, Director National Institute of Information and Communications Technology, 2-2-2 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0288 Japan, [email protected]

Written for presentation at the [2012 SMPTE Annual Technical Conference] Abstract. In order to enjoy a pleasant experience watching 3DTV, it is necessary to collect and analyze reliable safety assessment data. Evaluation experiments were conducted consisting of 500 adult participants watching 3D programes for approximately one hour on commercially available 46 to 50-inch 3DTVs that require the use of shutter glasses. The degree of fatigue after watching the 3DTV was evaluated under various viewing conditions based on objective and subjective indexes of fatigue. The results of objective indexes showed that there was no statistical difference between watching 3DTV and traditional TV (i.e., watching 2D programes without glasses) in degree of decline of visual and cognitive functions due to fatigue. On the other hand, the results of subjective indexes indicated that there were some differences between watching 3DTV and traditional TV in the sensation of fatigue, which may not be attributed to watching 3D programes, but to wearing the 3D shutter glasses. Keywords. 3DTV, viewing conditions, visual fatigue, fatigue evaluation

The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the Society of Motion Picture and Television Engineers (SMPTE), and its printing and distribution does not constitute an endorsement of views which may be expressed. This technical presentation is subject to a formal peer-review process by the SMPTE Board of Editors, upon completion of the conference. Citation of this work should state that it is a SMPTE meeting paper. EXAMPLE: Author's Last Name, Initials. 2011. Title of Presentation, Meeting name and location.: SMPTE. For information about securing permission to reprint or reproduce a technical presentation, please contact SMPTE at [email protected] or 914-761-1100 (3 Barker Ave., White Plains, NY 10601).

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Introduction In Japan, commercially available three-dimensional television (3DTV) is becoming popular and the case that people watch it for relatively long periods of time at home is increasing. In such a situation, 3DTV manufacturers, 3D contents producers and broadcasters are concerned about its influence on viewers. Although many studies have investigated the effects of 3D displays or 3D images on viewers, data remain insufficient on the safety of watching 3D programs with commercially available 3DTVs in typical home-viewing environments. To evaluate the fatigue caused by watching 3DTV under conditions that resemble typical viewing situations at home, we conducted experiments with 500 adults who watched 3D programs for approximately one hour on commercially available 46 to 50-inch 3DTVs that require shutter glasses. This experiment was done under the auspices of the 3D image evaluation committee of the Ultra-Realistic Communication Forum (URCF), which is a collaboration among industry, academia and government in Japan. This report describes the findings of fatigue caused by watching 3DTV based on experiments conducted from January to March 2011.

Overview of the Experiment Viewing Conditions Commercially available 46 or 50-inch 3DTVs that require shutter glasses were set in three preview rooms so that we could simultaneously perform experiments under three different viewing conditions. 3D programs were played with hard disk recorders (1920 × 1080 60 i/10 bit/4:2:2) as 3DTV format referred to as Side-by-Side, where the horizontal resolution of the HD image is reduced by half. For 2D programs, the right images of the 3D programs were replaced by the left images. The peak luminance of the 3DTVs was 100cd/m2, and the environmental illuminance of the preview rooms was 200 lux, which is the intermediate value of the illumination criteria in average living rooms in Japan (150 to 300 lux, JIS Z91101). Six types of viewing conditions were set: four in which participants watched 3D programs with glasses in front of a 3DTV at three different distances (two, three, and five times the screen's height) and from an oblique position of 40 degrees angle, and two control conditions in which they watched 2D programs with or without glasses in front of a 3DTV at a distance of three times the screen's height. Figure 1 illustrates the viewing positions and their abbreviated expressions.

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2

Figure 1 Six types of Viewimg conditions

Contents of 3D programs The 3D programs used in our experiment consisted of seven kinds of programs as shown in Table 1. The Interval of each program was ten seconds, and instructions to write down the degree of fatigue were displayed on the 3DTV at each interval. The binocular disparities of the 3D programs were generally less than one degree at the standard viewing distance, i.e., three times the screen's height. Five scenes had maximum disparities that exceeded one degree and their total durations were 39 seconds. The largest disparity was 1.57 degrees, and the duration of the longest scene whose disparity exceeded one degree was 15 seconds. Table 1 Contents Order Genre 1 Introduction of historic and sightseeing spots in Sydney, Australia 2 Soccer match 3 Classical music clip 4 Japanese festival 5 Clay animation 6 Japanese pop music clip 7 Documentary about Hiroshima Peace Memorial

Duration (mm:ss) 16:36 11:44 6:24 1:20 9:14 6:20 11:22

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Participants The participants were 500 women and men whose ages ranged from 20 to 69. Each participant watched 3DTV in only one viewing condition (between-group design). They were divided into eight groups by gender and age (F1: 20 to 29 year-old females, F2: 30 to 45 year-old females, F3: 46 to 59 year-old females, F4: 60 to 69 year-old females, M1: 20 to 29 year-old males, M2: 30 to 45 year-old males, M3: 46 to 59 year-old males, and M4: 60 to 69 year-old males). 82 to 85 participants were placed in each viewing condition so that each group had almost the same numbers as shown in Table 2. Table 2 Number of participants for each viewing condition 2DNG 2DWG 3D2H 3D3H 3D40 3D5H Total F1 10 10 10 10 10 10 60 F2 10 10 10 10 11 10 61 F3 11 10 10 10 10 10 61 F4 11 12 11 10 10 10 64 M1 10 10 10 10 10 11 61 M2 10 10 10 11 11 10 62 M3 10 11 11 11 11 11 65 M4 12 12 10 11 10 11 66 Total 84 85 82 83 83 83 500

Evaluation method of fatigue Since a standard evaluation method for visual fatigue remains unestablished, we evaluated visual fatigue with multiple indexes that have been used in previous research and in clinical fields. Visual acuity, Critical Flicker Frequency (CFF)2, and the Advanced Trail Making Test (ATMT)3 were used as objective indexes of fatigue. CFF, which is a psychophysical measure of visual temporal resolution, represents the minimal number of flashes per second at which an intermittent light stimulus provides a continuous sensation and may show visual fatigue and visual sensory sensitivity. ATMT evaluates mental fatigue. In this test, circles numbered from 1 to 25 are placed randomly on the display and participants are required to use a computer mouse to sequentially click on them. As subjective indexes, we used the Simulator Sickness Questionnaire (SSQ)4 and the Visual Analogue Scale (VAS)5. SSQ, which has often been used to measure the degree of visually induced motion sickness, contains 16 questionnaire items with a four-point scale. Total score of motion sickness and three subscale scores, which are Oculomotor, Nausea and Disorientation, are calculated from the scores of each item. VAS measures the subjective symptoms of fatigue where participants indicate its degree on a simple visual analogue scale. The "Guideline of Clinical Evaluation of Anti-fatigue"5 cited it as one of standard evaluation methods for fatigue. We evaluated the fatigue caused by watching 3DTV by the differences between those indexes evaluated before and after watching 3DTV. In addition, the participants answered questionnaires about their physical conditions after watching 3DTV on the experiment day and again on the following day.

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4

Procedure After explaining this experiment’s purpose and details and the possibility of discomfort and fatigue from watching 3DTV, participants signed consent forms. Next their pupil distances were measured and screening tests of stereoacuity were conducted with the Titmus stereotest. Fatigue was evaluated by SSQ, VAS, Visual acuity, CFF, and ATMT before and after watching 3DTV for one hour. Fatigue was also evaluated by VAS in the interval of each 3D program.

Results Participant characteristics 78.6% (393 of 500) of the participants have seen 3D images (movies, TV programs and computer games) once at least, and 48.6% (191 of 393) of them have felt fatigue caused by 3D images. The means (with standard deviations in parentheses) of the pupil distances of all participants, female participants, and male participants were 62.75 (3.44), 61.00 (2.88), and 64.43 mm (3.08), respectively. Figure 2 shows the mean pupil distance of each group. There were significant differences between all female groups and all male groups. 13.8% (69 of 500) of the participants were unable to perceive disparity of two minutes or less, and 2% (10 of 500) had no stereoscopic vision. Evaluation data of these participants were retained because all groups almost uniformly contained such participants. The state of participant fatigue before this experiment may affect the fatigue caused by watching 3DTV. Even though controlling participant fatigue before our experiment was difficult, we identified whether bias existed in it before watching 3DTV between the viewing conditions. The before watching 3DTV scores of all the objective and subjective fatigue indexes indicated no bias between viewing conditions because there were no main effects of viewing conditions with a two-way Analysis of Variance (ANOVA) for each index.

Figure 2 Mean pupil distance of each participant group

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5

Differences of fatigue for viewing conditions The mean values of each fatigue index was obtained for each viewing condition and two-way ANOVA and Multiple Comparison tests (Tukey-Kramer method) were conducted to determine whether these values show significant differences between viewing conditions. Visual acuity, CFF, and ATMT indicate visual and cognitive functions, as mentioned above. Therefore, the differences between these objective indexes before and after watching 3DTV indicate the decline of visual and cognitive functions due to fatigue. The differences of these objective indexes were very small in all the viewing conditions, and a two-way ANOVA demonstrated that the main effect of the viewing condition was not significant for all the objective indexes. The results of the objective indexes indicated no differences between viewing conditions in the decline of visual and cognitive functions due to fatigue. On the other hand, the differences between the subjective indexes before and after watching 3DTV were increased in all the viewing conditions, except 2DNG. A two-way ANOVA demonstrated that the main effect of the viewing condition was significant for the Total Score of SSQ, F(5,452)=3.46, p=0.004, the Oculomotor of SSQ, F(5,452)=3.66, p=0.003, the Disorientation of SSQ, F(5,452)=3.56, p=0.004, VAS, and F(5,452)=2.68, p=0.021. Figure 3 shows mean difference value of the subjective indexes which indicate the main effect of viewing condition for each viewing condition. With respect to these subjective indexes, Multiple Comparison tests were conducted to investigate the differences between viewing conditions. For the Total Score of SSQ, there were significant differences between 2DNG and each of 3D3H and 3D40, and marginally significant differences between 2DNG and each of 2DWG and 3D5H. For the Oculomotor of SSQ, there were significant differences between 2DNG and each of 2DWG, 3D3H, 3D40 and 3D5H, and a marginally significant difference between 2DNG and 3D2H. For the Disorientation of SSQ, there were significant differences between 2DNG and each of 3D3H and 3D40, and marginally significant differences between 2DNG and 3D2H. For VAS, there was a significant difference between 2DNG and 3D3H.These significant and marginally significant differences between viewing conditions are illustrated by lines with p-values in the charts of Figure 3. From these Multiple Comparison test results, it is considered that there were differences in the sensation of fatigue between watching 3DTV and traditional TV (i.e., watching 2D programs without glasses). However, these results show no significant differences between the viewing condition in which participants watched 2D contents with glasses and the viewing condition in which participants watched 3D contents with glasses. Furthermore, these results show significant differences in several subjective indexes between the viewing condition in which participants watched 2D contents with glasses and the viewing condition in which participants watched 2D contents without glasses. Therefore, it is considered that differences between watching 3DTV and traditional TV may not be attributed to watching 3D content, but rather to wearing 3D shutter glasses. Unfortunately, we couldn’t identify such significant differences between viewing 3D and 2D contents without glasses, because a commercially available glasses-free 3DTV did not exist at the time of our experiments.

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Figure 3 Mean value of subjective indexes that showed main effect of viewing condition for each viewing condition Figure 4, which shows the questionnaire results about their physical conditions after watching 3DTV, indicates the ratio of participants who reported poor physical conditions on the experiment day and on both the experiment day and the following day for each viewing condition. Reported symptoms of poor physical conditions included tired or sore eyes, dry eyes, watery eyes, shoulder stiffness, neck stiffness, headaches and fatigue, all of which are typical problems related to eyestrain. Figure 4 suggests the possibility that the ratio of participants who reported poor physical conditions in 3D2H is higher than in other viewing conditions. Fisher's exact test was conducted to investigate the differences between the viewing conditions in which participants watched 3D content for the ratio of participants who reported poor physical conditions. As a result, there was a significant difference between 3D2H and other watching 3D content viewing conditions for the ratio of participants who reported poor physical conditions on both the experiment day and the following day, p=0.045. On the other hand, as shown in Figure 3, there were no significant differences between 3D2H and the other watching 3D content viewing conditions for the subjective indexes of fatigue. In

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7

order to investigate this discrepancy, Multiple Comparison tests were conducted on the differences between the group of participants who reported poor physical condition and those who did not report a poor physical condition. There were significant differences between the group of participants who reported a poor physical condition on the experiment day and those who did not report for Total Score, Oculomotor, Nausea and the Disorientation of SSQ. Figure 5 shows the mean value of the Total Score for each group. This result shows that participant who reported poor physical condition felt the fatigue immediately after watching 3DTV.

Figure 4 Questionnaire results about their physical conditions after watching 3DTV

Figure 5 Mean Value of the Total Score of SSQ for the group of participants who reported poor physical conditions.

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8

These results suggest that the sensation of fatigue may be present until the next day if 3DTV is watched at a distance closer than the standard viewing position (i.e., three times the screen's height). The reason for no significant differences between 3D2H and the other watching 3D content viewing conditions for the subjective indexes of fatigue is that because the ratio of participants who reported poor physical conditions was very low as shown in Figure 4, their SSQ scores did not affect the mean value of SSQ scores.

Conclusion We conducted evaluation experiments with 500 adult participants who watched 2D/3D programs for approximately one hour on commercially available 46 to 50-inch 3DTVs that require shutter glasses. The following results were obtained: •

There was no difference between watching 3DTV and traditional TV in the degree of the decline of visual and cognitive functions due to fatigue.

•

There were differences in the sensation of fatigue between watching 3DTV and traditional TV. However, these differences may not be attributed to watching 3D content, but to wearing the 3D shutter glasses.

•

The sensation of fatigue may be present until the next day if 3DTV is watched at a distance closer than the standard viewing position.

It should be noted that the results of the present study were obtained under conditions that closely resemble typical viewing situations at home, where the participants simply watched 3D programs whose binocular disparities were relatively small on commercially available 46 to 50inch 3DTVs. Therefore, these findings may not fully apply to other viewing conditions and more 3D content that have large disparities.

References 1.

Japanese Industrial Standards, JIS Z9110, "General rules of recommended lighting levels"

2.

T. Mitsuhashi, "Evaluation of Stereoscopic Picture Quality with CFF," Ergonomics, Vol. 39, No. 11, 1996

3.

O. Kajimoto, "Development of a Method of Evaluation of Fatigue and its Economic Impacts," in Fatigue Science for Human Health, New York: Springer, 2008

4.

R. S. Kennedy, et al., "Simulation Sickness Questionnaire: An Enhanced Method for Quantifying Simulator Sickness," The International Journal of Aviation Psychology, Vol. 3, No. 3, pp. 203-220 1993.

5.

Japanese Society of Fatigue Science, "Guideline of Clinical Evaluation of Anti-fatigue," http://www.hirougakkai.com/VAS.pdf (in Japanese)

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