1. THE LIE DETECTOR Tim Fleck Tim Fleck Mike Gruener Mike Gruener Brian Halaburka Brian Halaburka Chris Moskaites Chris Moskaites

2. OBJECTIVES  To create a sensing device modeled after a polygraph test  Test would incorporate results from several physiological sensors  Create a Labview program to gather and analyze subject data

3. POLYGRAPH THEORY  Polygraphs measure:  Heart rate  Respiratory rate  Blood pressure  Arm and leg motion  Electrodermal activity

4. INITIAL IDEAS  Use real world polygraphs as design models  Assemble a polygraph which monitors heart rate, breathing rate and electrodermal activity  Create a Labview program which would self-analyze data and “detect” deceptive behavior

5. FINAL LIE DETECTOR  Incorporates two physiological sensors detecting two phenomenon 1)electrodermal activity 2)motion  Self analyzes received data

6. DETECTOR LOGIC Subject Electrodermal Sensor/Motion Sensor DAQNew Data LABVIEW/CPU Display Results

7. SENSORS  Electrocardiogram or EKG  Galvanic Skin Response Sensor

8. ELECTROCARDIOGRAM  Measures the electrical activity of the heart  Determines hearts rate and rhythm  Our project used it to measure motion

9. GALVANIC SKIN RESPONSE SENSOR  Senses moisture  Stand-alone unit  Produces noise  Frequency was too fast for the DAQ

10. CREATED SKIN SENSOR  Based off the idea that skin resistance decreases with moisture  Used a voltage difference circuit  Amplified the voltage difference to obtain obvious results

11. LABVIEW LOGIC (EKG)  Take initial readings visually from the waveform graph  Calibrate the high and low end of the threshold based on the initial readings  Every question after will be compared to the threshold  If a person’s motions go above the threshold, a LED goes on, indicating a lie

12. LABVIEW LOGIC (GSR)  Takes voltage readings of subject’s fingers until button is pushed  Then it computes and displays and average voltage for the given time period  Displays a waveform chart showing how much the subject’s voltage is increasing from the average as resistance decreases  If the in average increase goes above a certain predetermined value, a light goes on, indicating a lie

13. DATA  Thresholds were determined by analyzing results gathered from group testing  Normalized against predetermined values

14. DATA ANALYSIS AND RESULTS Galvanic Sensor:  Computes voltage average  Determines a lie if the subject’s voltage goes above a threshold

15. DATA ANALYSIS AND RESULTS EKG:  Displays the electrical impulses generated by a human body  When a certain level of voltage is generated in the body it rises above a predetermined value indicating irregular behavior  Detects movements from bodily extremities, specifically the arms and legs

16. NORMAL EKG WAVEFORM

17. DECEPTIVE WAVEFORM

18. SOURCES OF ERROR  Nervousness of test subject  Calibration errors

19. Difficulties  Heart Rate Monitor  Galvanic Skin Response  LABVIEW  Lab Setup

20. CONCLUSIONS  “Simple” circuitry increases in complexity once work begins  Check and recheck components before and after assembly  Start early  Be flexible and constantly improve