GSR-POLYGRAPH LAB Physiology lab

GSR-Galvanic SkinResponse Electricity flows through an electrical circuit because of difference in the electrical pressure between the beginning and the end of a circuit. Electrical pressure (electromotive force-E) is measured in volts (V). The flow of electricity is called current (I=amperes) As electricity flows through the circuit, resistance (R) is measured in ohms (Ω) Ohm’s law: I (Amps)= E(Volts)/ R (Ohms)

In this lab We’re going to apply principles of Ohm’s Law and record changesin the electrical resistance of the skin. GSR (Galvanic skin resistance) – When a feeble electric current is steadily applied between two electrodes placed about an inch apart, the recorded electrical resistance between them, referred to as GSR (depends on subject’s emotional state) Galvanic skin potential (GSP) – Similarly if the electrodes are connected to a suitable voltage amplifier, but without any externally applied current, the voltage measured between them, referred to as galvanic skin potential (GSP) Galvanic skin response

It is effected by autonomic tone (largely sympathetic) occuring in the skin and subcutaneous tissue in response to a change in the state of the subject. Changes in peripheral autonomic tone alter sweating and cutaneous blood flow, which in turn change GSR and GSP.

A polygraph The detection and recording og the galvanic skin responce is often combined with the detection and recording of other autonomic- dependant psycophysiological variables such as heart rate, respiratory rate nad blood pressure. The device that detects and records these variables is called polygraph.

The experiment We’re gonna measure: Respiratory responses Heart rate and GSR simultaneously.

Calibration Seat teh subject facint the director and away from the screen. Click calibrate Three sec.after a beep will sound and subject should inhale and exhale deeply for one cycle then return to normal breathing. End calibr.

There are 3 segments 1. seg: Subject faces the director – recorder faces screen and listens the directors instr. To subject. Click record Wait 5 secs Recorder needs to insert an event marker at the precise moment that the subject answers each question (F9)

Questions Quietly say his-her name () Quietly count backward from 10 ( count from 10 ) Count backward from 30 by substracting increasing odd numbers-exmp. 30,29,26,21 (count from 30) Director touches subject on the side of the faceface touched Click suspend Name

Seg2 Click resume Director holds paper 1 about two feet from subject’s face Display the colors and insert event markers in the following order: white black brown purple yellow orange blue green red

Seg3 Click resume Director asks subject the ten questions. Subject responds yes or no Recorder inserts event markers when the question asked and when the answer starts

Analysis Set up your display window for optimal viewing of the first 5 secs of the recording. Set up the measurement boxes as follows

Respiration rate

GSR Scroll to view a 10 secs interval beginning at the first event marker

BPM