week 10 summary – Hitesh
Variations in Physiological Responses of Participants During Different Stages of an Immersive VirtualEnvironment Experiment
The paper talks about measuring presence in a virtual environment through the physiological responses of a user in the system. It defines Presence as use’s response to virtual stimuli when there is a successful substitution of real sensory data by computer generated sensory data. The experiment focused on physiological responses – heart rate and heart rate variability. An important parameter was the level of stress the participant undergoes during the course of the experiment. Physiological signals were recorded when participants walked through a CAVE-like virtual street environment with virtual people walking through the street. The texture quality of the virtual environment and visual realism of the characters were altered to measure change in responses, physical and stress levels of the participants.
The mental stress seems to increase at the beginning of the experiment mainly attributed to the first time experience and anxiety, and then it decreases at the beginning of the actual experiment as user becomes more comfortable with the system, and it increases again at the end of the experiment as the physical stress increases and user is able to perceive more technical glitches in the system. I believe stress level is a very effective instrument to measure presence in a virtual system but it could be subjected to several other personal and physiological parameters which are hard to quantify.
The Uncanny Valley: Effect of Realism on the Impression of Artificial Human Faces
The main purpose of the paper seems about studying Mori’s hypothesis related to the extent to which the physical appearance of humanoid robots should be made close to real humans. As described by Mori, there is an ‘Uncanny valley’ which refers to the unpleasant and negative experience that user has if the robots or visual characters have a high degree of human realism. In order to test the hypothesis, an experiment was carried out where participants were shown various visual characters that sequentially morphed into a human like face. The participants were asked to rate each image on a numeric scale from pleasant to unpleasant. The study however reflected that apart from extent of realism, uncanny valley emerged when the abnormality of the features changed in the face. People focus on different facial features such as age, gender and impressions of the face. Irrespective of the degree of realism achieved, the abnormal features of visual characters manifest to unpleasant experiences. The paper also highlights that human visual system perceives realism and abnormality based through different visual features such as eyes, skin color, youthfulness etc., all of which were not taken into account in the study.
Physiological Measures of Presence in Stressful Virtual Environments
The paper talks about an extensive set of parameters that could help measure the Presence of a Virtual Environment. If the physiological responses in a virtual environment are as similar to responses evoked in a real environment, then the VE has a higher degree of Presence. Parameters used for measurement were changes in heart rate, variations in skin conductance and skin temperature. 3 different experiments were carried out to observe the variation in stress levels. The first experiment measured the level of stress while being subjected to the repeated exposure of Virtual environment through a simple task. The other experiments were aimed at measuring the effect of passive haptics in presence.
The experiment consisted of a 20 feet virtual pit, in which users had to navigate and place objects on specific spots. In one experiment, pit was plain floor while there was a wooden plank in the other which provided a greater realization of height and results indicate that it increased the stress level. Frame rates were also modulated to correlate the increase in presence with increase in frame rate. I feel the haptic feedback through wooden plank would be the strongest contributing factor to greater presence in the system.
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