Effect of Latency on Presence in Stressful Virtual Environments Analysis by The Team: Justin Gosselin, Maya Hughes, Allison Smith

Authors Frederick 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 Hill Research Associate Professor Current research interests: Effective Virtual Environments Sharif Razzaque ~ UNC - Chapel Hill PhD Dissertation in Redirected Walking Michael Meehan ~ Stanford University Research 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 3

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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 Study Control Group: 50ms latency Experimental Group: 90ms latency Description of this Study 5

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 Does relate to the the research question Literature Evaluation 6

Visitors of SIGGRAPH 2002 conference 195 participated in demo 32 female, average age 35 (σ = 10.9) 164 passed the inclusion criteria Usable heart rate, 61 participants 50ms; 90ms Usable skin conductance, 67 participants 50ms; 90ms Study Subjects 7

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 8

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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) questionnaire Simulator 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 10

Statistical tests at significance level of 5%: P < 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 < level Correlations between measures were analyzed Between physiological measures and self-reported measures Analysis 11

Conceptual: provides variables for experimentation Conditions of latency, physiological data, self-reported data Model: Took measures to confirm reliable experiences Quantitative as well as qualitative data Conceptual Framework 12

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 13

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 14

Discussion 1.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? 15

Agree or Disagree? Relatable? Closing Statements 16