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Effect of Latency on Presence in Stressful Virtual
Environments
Analysis by The Team:Justin Gosselin, Maya Hughes, Allison Smith
AuthorsFrederick P. Brooks, Jr. ~ UNC - Chapel Hill
Kenan Professor at UNC - Chapel Hill
Current research interests: Effective Virtual Environments, HCI, 3D Interactive Computer Graphics, Scientific Visualization
Mary C. Whitton ~ UNC - Chapel HillResearch Associate Professor
Current research interests: Effective Virtual Environments
Sharif Razzaque ~ UNC - Chapel HillPhD Dissertation in Redirected Walking
Michael Meehan ~ Stanford UniversityResearch in physiological reactions in virtual environments
Funding sources: Office of Naval Research, NIH National Center for Research Resources, and the National Institute for Biomedical Imaging and Bioengineering 2
What is the effect of latency on the internal state of participants in a stressful virtual environment?
Hypotheses:1. A better VE (lower latency) should elicit more
presence, and therefore, should elicit more of a change in heart rate and skin conductance than the less realistic VE
2. The severity of simulator sickness should be lower in the lower latency VE
Research Question
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https://www.youtube.com/watch?v=_fNp37zFn9Q
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Why study this? VEs are becoming more popular for a variety of tasks
VE effectiveness is often measured in terms of the minimization of factors that break user presence and/or hinder performance, such as latency
“Latency is known to have an adverse effect on both user performance and comfort in VEs”
Randomized Blinded StudyControl Group: 50ms latencyExperimental Group: 90ms latency
Description of this Study
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Reliable but not recent; credible journals and conferences
Some references are written by the author(s)
This publication is written in 2003
References are from 1986-2003
Does relate to the the research question
Literature Evaluation
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Visitors of SIGGRAPH 2002 conference
195 participated in demo
32 female, average age 35 (σ = 10.9)
164 passed the inclusion criteriaUsable heart rate, 61 participants
32 @ 50ms; 29 @ 90ms
Usable skin conductance, 67 participants34 @ 50ms; 33 @ 90ms
Study Subjects
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Inter-pupillary distances measurements
Demographic & Simulator Sickness questionnaires
Three-lead EKG, skin conductance sensors, telemetry system
Replaced HMD earphones with Sennhesier HD 250 II sealed
headphones
Recorded instructions to tell the participant how to perform the task
Stand on a ledge and drop bean bags onto their respective targets in
the pit
Variable: latency; measured using a photodiode and a pendulum
Method
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Physiological Data:Change in heart rate (goes up in stress)
Change in skin conductance (more sweat in stress)
Self-Reported Data:Fear & Presence (University College London) questionnaireSimulator Sickness (Kennedy) questionnaire
Consists of 16 symptoms, ranging from general discomfort to vertigo
A scoring and weighting system records the severity of each symptom
Data Collection
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Statistical tests at significance level of 5%: P < 0.050
Reaction to the Pit Room was analyzed using a T-test on physiological
measures
Because the ∆Heart Rate was borderline significant (P = 0.050), it was
corrected for Latency and Nausea
This was done because an increase in nausea causes an increase in
heart rate
This made ∆Heart Rate significant at a P < 0.050 level
Correlations between measures were analyzed
Between physiological measures and self-reported measures
Analysis
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Conceptual: provides variables for experimentationConditions of latency, physiological data, self-reported data
Model:Took measures to confirm reliable experiencesQuantitative as well as qualitative data
Conceptual Framework
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ΔHeart Rate was greater for lower end-to-end latency
Lower latency corresponds with higher presence and elicits more physiological
reaction
ΔHeart Rate did not correlate significantly with any self-reported measures
ΔSkin Conductance non-significantly higher in 90ms latency
Correlation between ΔSkin Conductance and Nausea
Hypothesis was correct as many times as it was wrong
Limitations: lack of knowledge about Fear-Simulator Sickness correlation
No significant relationships between latency and simulator
sickness
Results/Conclusion
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Can be replicated and was anticipated for our project with the demo
app
Low end-to-end latency increases sense of presence and elicits a
change in heart rate (more effective VE)
Latency is an important factor in VEs and their effectiveness and is
worthy of being measured, controlled, and reported in VE research
Significance
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Discussion1. What are your reactions to latency when playing your game
system? 2. What are some examples of latency that we see in our
everyday lives?3. Do you think the results of this study would be different today,
12 years later?
4. This study used a head-mounted display. How do you think the study would compare to a body-based system, like a Kinect?
5. What other factors could hinder user presence and/or performance in a virtual environment?
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Agree or Disagree?
Relatable?
Closing Statements
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