GSR-POLYGRAPH LAB

1. GSR-POLYGRAPH LAB Physiology lab

2. 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)

3. 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

4. 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.

5. 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.

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

7. 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.

8. 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)

9. 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 face face touched • Click suspend Name

11. 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 red blue green yellow orange brown purple

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

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

15. Respiration rate

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

17. BPM