Summary Week – 10
Physiological Measures of Presence in Stressful Environments:
Presence is mostly defined as the sense of being in a VE. There have been many views on the measure of Presence. In the paper authors propose physiological changes as a measure of presence in the VE. They state that the degree to which VE seems real can be determined by the physiological changes evoked. According to the authors the response to a VE would be similar to corresponding real world situations. They also state that greater the presence greater the response. To prove their theory they conduct an experiment and measure 3 physiological factors, namely Heart Rate, Skin Conductance and Skin Temperature. The experimental setup consists of two rooms, a training room and a pit room. Users are practice in the training room where they move around, pick up and place objects. Pit room consists of an unguarded virtual hole and a 20ft virtual drop into furnished living room. Once the users are acquainted to the VE in the training room they are asked to carry an object into the pit room and place it on a chair at the other end of the room across the hole. Further three experiments are performed, to measure the change in parameters. In all the experiments Heart Beat came out to be the best parameter to measure, followed by Skin Conductance. In the second case where the users were made to stand on a plank with toes outside the plank due to unavailability of the Heart Beat sensors, Skin conductance came out to be the best measure. Change in frame rate also had a considerable impact on the responses.
Though the results were pretty conclusive there is drawback in the experiment. The set up arouses fear, but it has no measure of pleasure, relaxation and other parameters. Hence it may be interesting to see how the parameters fare when tested in relaxing VE’s.
Variations in Physiological Responses of Participants during Different Stages of an Immersive Virtual Environment Experiment:
The paper discusses the physiological responses of participants when introduced to a virtual environment. Authors used HRV algorithm on the ECG signals collected from the participants during the three stages of the experiment to come to a conclusion. The participants were placed in a cave like system where VE is projected. . The experiment is divided into 3 parts. First being the baseline recordings where the participant is asked to stand in a dark corner for 90 sec to record the ECG values to be used as a base for future parts. In the second part participants were put in a virtual room in which single digit 3D numbers floated on the floor and the participants were asked to navigate through the room by following the numbers in a sequence of 0-9. In the final part of the experiment the participants were asked to stand in front of a virtual door leading to a virtual street filled with characters. At a time only 8 out of the 16 possible characters could be seen to avoid collision. The participants were asked to signal any break in presence by pressing the joy stick. The focus of the experiment was to perform the HRV analysis on both time and frequency domain in order to detect difference in physiological responses of the participants, in different scenarios. From their analysis authors were able to conclude that participants react with stress when introduced to the environment initially, but as they get used to it the stress levels go down till the time they feel the environment to be repetitive and lacking changes. Authors also found that participants’ stress levels went up considerably in the training phase and thus suggest future experiment to have an extended training segment.
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