Galvanic Skin response (GSR)

A low level of cortical arousal is desirable for relaxation, hypnosis, and the subjective experience of psychic states and unconscious manifestations.
A high level of cortical arousal gives increased powers of reflection, focused concentration, increased reading speed, and increased capacity for long-term recall.
Cortical arousal has a simple relationship to skin conductivity. Arousal of the cortex increases the conductivity of the skin and conversely, a drop in arousal causes a drop in skin conductivity. With a sensitive meter the level of arousal can be brought under conscious control. With a few hours' practice the level of arousal can be consciously controlled over wide


Galvanic Skin Response(GSH/GSR) or Electrodermal Response (EDR)


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Galvanic skin response (GSH) or Electrodermal Response (EDR)

Also known as Electrodermal Response (EDR), Galvanic skin response measures electrical conductance in the skin, which is associated with the activity of the sweat glands. A very slight electrical current (unnoticeable to you) is run through your skin. The machine measures changes in the salt and water in your sweat gland ducts. The more emotionally aroused you are, the more active your sweat glands are and the greater the electrical conductivity of your skin. GSR is effective in treating phobias, anxiety, excessive sweating, and, at times, stuttering since these emotions will affect your skin's conductivity. It is used as a lie detection test. Athletes use this technique to prepare for games - to make sure that they are not too anxious or have pre-game jitters.


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Media Research with a Galvanic Skin Response Biosensor: Some kids work up a sweat!

ABSTRACT

This study considers the galvanic skin response (GSR) of sixth-grade students (n=20) using print, video, and microcomputer segments. Subjects received all three media treatments, in randomized order. Data for analysis consisted of standardized test scores and GSR measures. A moderate positive relationship was shown between cumulative GSR and standardized test scores (r = 0.50). The higher achieving students obtained higher GSR values. Patterns of arousal with each media were analyzed by analysis of variance with repeated measures. The interaction of media and time was significant at the p < .05 level (F(14, 266) = 1.985). The patterns of response towards the print and microcomputer treatments were very similar, and both were quite dissimilar to the pattern of response for video. Specifically, video obtained the highest GSR response initially, and GSR response remained constant throughout the 21-minute data collection period. Print and microcomputer obtained relatively lower GSR responses initially, then matched the GSR response level of video after about 10 minutes, and continued to increase throughout the data collection period. This finding has not been previously reported and reconciles earlier conflicting findings.

Analysis methods for GSR
The wave shape is usually biphasic or triphasic and lasts several seconds. Because GSRs are such long lasting waveforms inter-stimulus intervals (ISIs) should be long enough. When using short ISIs response overlapping should be considered by decomposing the overlapped responses.

Normally reproduced within-subject GSRs have common features in waveshapes. Amplitudes tend to habituate, latencies might increase slightly and waveshapes remain fairly unaltered in repetitions. The decrease in amplitudes and increase in latencies is affected by the weakening of the surprise effect of stimulation and by the weakening of alertness of the subject during the experiment.

In recording situations some low pass filter can be used to avoid high frequency noise. As the signal-to-noise ratio (SNR) of the GSR signal is high individual responses are usually studied without any signal processing. In some studies several responses are averaged but this can lead false interpretation due to variability of the response. Thus, it is generally suggested that averaging should not be used.

Final Report on Project on An Examination of Response Parameters of Electrodermal Responding to Standard Stimuli
Abstract: This report contains the results of two studies of the relative merits of using skin conductance or skin resistance to evaluate the amplitude of electrodermal responses to external stimuli. The studies also addressed the relative merits of correcting responses for baseline, rather than using raw amplitude measures. The first study employed an oddball paradigm to determine whether skin resistance or skin conductance, or baseline corrected ratio measures are best suited to discriminating oddball stimuli from a background of frequently occurring standard stimuli. The results indicated that there is no empirical basis for assuming that any particular measure has any advantage in allowing for reliable indexing of response differences between oddball (i. e., "novel") and standard stimuli. This suggests the possibility that the use of uncorrected amplitude measures in field applications may be as reasonable as any other technique. The second study attempted to determine if any electrodermal index was more well suited than others for assessing the magnitude of response to external stimuli differing in intensity. The data indicated that there was no apparent advantage to using any particular index of electrodermal response magnitude in favor of any other. All indices showed the same response curves with respect to stimulus intensity and subjective magnitude estimation of stimulus intensity.


The Effect of Sound Delivery Methods on a User's Sense of Presence in a Virtual Environment
Abstract: The purpose behind this thesis was two-fold. First, the effect of sound delivery on a user's sense of presence in a virtual environment was investigated. Second, the physiological responses of electrodermal activity, heart rate, end temperature were measured end correlated to the user's subjective sense of presence in an attempt to determine if physiological measures can be used in the future as en objective measure of presence. A computer based first-person shooter gene (Medal of Honor: Allied Assault(Trademark)) was utilized as the virtual environment. The independent variable wee sound delivery method (no sound, 5.1 surround sound, headphones, end headphones with subwoofer). The dependent variables were physiological response end questionnaire results. Results indicated that sound contributed to the user's sense of presence as evidenced by electrodermal activity and temperature end questionnaire scores. Also, significant changes occurred between the speaker end headphone sound delivery methods. This response suggests that speakers crested a higher sense of emotion and possibly induced a higher level of presence in participants.



Galvanic Skin Response Experiments


Homemade GSR by ITP students-Tom Igoe
GSR-Image