Skin Conductance (GSR) and Temperature Designs

Skin conductance and skin temperature, measured from the hands, are considered indicators of Autonomic Nervous System activity. In most cases it is changes in these parameters (rather than absolute measurements) that is of primary interest, so it's important to calculate rate of change. Most feedback is based on this calculation. Skin conductance is also known as Galvanic Skin Response (GSR) and Electrodermal Response (EDR).

The two design suites (i.e. skin conductance and temperature) are in most ways functionally equivalent. Some designs monitor both parameters.

Design features

• Dual screen designs (therapist and client) included
• Automatic calculation of baseline (average over first 30 seconds)
• Button option to reset baseline (to average over the last 30 seconds)
• Calculation of gain over baseline

Graphical Feedback Features

• 30 or 60 S trend displaying rate of change
• 
• oscilloscope
• 
• long term trend (default 10 minutes)

Audio Feedback Features

Each audio feedback option can be switched on and off using a button.

• Tone and midi: feedback via pitch
• Auto-recalibrate feature: when pitch drifts out of range, it automatically resets to the middle of the pitch range
• Sensitivity can be easily adjusted
• Rate of change feedback via volume - sound goes quiet when the signal is stable/unchanging
• Threshold-based feedback: a reward or warning repeatedly sounds when the rate of change falls out of range for a sustained period

Video Feedback

Some of the designs use the Video Player object as the principle vehicle for feedback. Here, the forward motion of the video is constrained by the biofeedback signal's rate of change. More specifically, the speed of forward motion depends on the rate of change in relation to a double threshold - e.g. forward motion stops at the lower threshold and reaches a maximum speed at the upper threshold. There is accompanying audio feedback.

When the signal moves in the "wrong" direction, the video will either remain stationary or move backwards, depending on the state of an option button.

DVD Feedback

Other designs use the DVD Player as the main form of feedback. Again feedback is constrained by the signal's rate of change in relation to a double threshold. When the signal is moving in the "wrong" direction, the picture quality degrades by either "greying out" or by shrinking. Sound quality is also degraded. Conversely, when the signal moves in the "right" direction, the picture is unimpeded.

Sample Screenshots

Click on the thumbnail to see the full-scale image.

	1. Skin Conductance Design The uppermost trend shows the rate of change of the skin conductance signal, which is shown in the middle oscilloscope (which also shows skin temperature) and the lower long term trend.
	2. DVD Design Here the DVD is the principle mode of feedback but you also see a long term trend display of skin conductance. Note the layout of the video design is substantially the same. A dual screen version shows only the DVD display in the client's screen.

For further information see the User Guide for the breathing designs. This can be downloaded for free. Visit the downloads page by clicking the link in the navigation menu.

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