Summaries Week 10
Physiological Measures of Presence in Stressful Virtual Environment
“Presence” is a measure of the quality or effectiveness of the virtual environment. Attempt was made to measure presence in ways which were reliable, valid, sensitive and objective. If the physiological responses were similar to ones in the real world would mean that the VE seems real. Change in heart rate was the best measure to determine this. The variation in skin conductance and skin temperature were additional measures used.
The experiment consisted of users equipped with head-tracked stereoscopic head-mounted display, practice walking about and picking up and placing objects in the Training room. The users were expected to carry the object to the next room walking through a virtual hazard, a drop of 20 feet. Three experiments including effects of multiple exposure on presence, effect of passie haptics and and the effect of frame rate on presence were measured.
The parameters like rate of video feed and time exposed to the VE were changed in various experiments. The results showed that all presence measure decrease over multiple exposures to the same VE. The inclusion of passive haptics significantly improves presence. The hypothesis that the frame rate has a strong impact on presence was also confirmed by experiments during the study.
One question that I have in mind is whether any of the participants already have a fear of heights. Could this possibly influence the findings in any way?
Variations in Physiological Responses of Participants During Different Stages of an Immersive Virtual Environment Experiment
This paper discusses the use of physiological responses as a technique to evaluate stress levels during virtual experiences. The participants have different responses to the environment in different phases of the same virtual experience causing different mental and physical states. The goal is to quantify these responses of varying stress levels in some way. For instance, the Heart Rate and the electro dermal activity (EDA) increases with stress levels. The scenario of the experiment was a replica of the street with virtual people walking around. A CAVE-like system was used for the experiment. The physiological responses of the participants in the different segments: baseline, training and actual experiment segments were calculated. Firstly, the analysis indicated that being introduced into an immersive virtual environment created a stressful situation for the participants, compared to pre-experience baseline session. The stress level decreased once they got inside a more natural-looking and engaging environment as they became used to the technology and comfortable in it. Also, it was observed that non-repetitive textures resulted into more realistic environment which influenced the mental stress on the participant. Longer the experiment greater the stress as the participants become aware of the problems in the system.
In summary the stress levels seem to increase at the beginning of the virtual experience during the training, and then it decreases during the experiment and then increases again later on in the experiment as the participants get used to the environment and remove more faults with it.
The Uncanny Valley: Effect of Realism on the Impression of Artificial Human Faces
It’s a belief in the world of Robotics that people have an unpleasant impression of a humanoid robot that has an almost but not perfectly realistic human appearance. This study tries to quantify and provide evidence to this term “pleasantness”. According to Mori the level of pleasantness increases as the robot becomes more real until it reaches the uncanny valley where it drops for a bit and then again increases linearly. Morphing images of dolls to human were provided in a web-based experiment and the participants had to rate the degree of pleasantness for each. In experiment 1 the results show Mori’s claim of “Uncanny Valley” because the images were either too real (region A) or too humanoid (region B) of the degree of realism. From the 2nd experiment it was clear that the sequence in which parts like the eyes and head were morphed had an effect on the pleasantness. Asynchronous morphing was a necessary condition for the uncanny valley’s emergence. Further experiments were conducted to understand how the eye size and its realism had an effect of participants. Even though Mori’s prediction was proved right it was observed that uncanny valley emerged only when the face images involved abnormal features. In conclusion, the human visual system may define realism and abnormality based on different visual features and the distinction between them is not so straightforward.
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