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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