ExperimentB-37
Emotional StressMeasurement
Objectives
- To learn about the fight or flightresponse.
- To examine how stimulation of the human system (bytouch, smell, sight or sound) causes the sweat glands in the handto secretesweat.
- To understand the principles of a polygraph (liedetector).
Modules andSensors
- PC + Edu-Loggerapplication
- USBmodule
- GSR (Galvanic Skin Response) logger sensor
Equipment andAccessories
- Wash bottle (or aglass)
- Cottonpad
- Pen
Materials
- Blankcard
- Water for washbottle
- Bottle of alcohol, perfumeor cologne
Introduction
Emotional and sensory stimulation causes the production ofsweat. The GSR (Galvanic Skin Response) logger sensor is usedto measure sweat coming from the sweat glands of a hand. As aresult ofthestimulation,theamountofsweatincreasesandsodoesthe skinconductivity.
Why is sweat produced by emotionally and sensory stimulation?The fight or flight response is activated as a result of an acute threatto survivalandpreparesanimalstoreactorretreat.Whenathreatis perceived, the sympathetic nervous system (a part of theautonomic nervous system) is activated. This leads to the release ofthe hormonesnoradrenalineandadrenaline.Thesehormonesbindto adrenergic receptors on peripheral tissues. The binding leadsto pupildilation,anincreaseinheartrate,bloodpressure,breathing rateandsweatproduction.Sweatisproducedinthefightorflight response in order to help the body to get rid of extra heatgenerated by increased muscularactivity.
Humans have several millions of sweat glands which lie inthe middlelayeroftheskin(thedermis).Whensweatisproduceditis transported to the surface layer called the epidermis through aduct. There are a number of areas in the body with high concentrationsof sweat glands, such as the forehead, the palms of the hand, thearm pits, and the soles of thefeet.
The GSR measurement is included in a Polygraph (a liedetector). Lying induces a stressful state on the body, which is manifestedvia physiological responses. Except for skin conductivity, a polygraphis capable of simultaneously recording changes in bloodpressure, pulse rate, respiration and others, while the subject is asked aseries ofquestions.
In this study, you will learn how humans react when theyare emotionally stimulated. You will observe that the handproduces sweat when the brain is stimulated. You will also record thechanges in sweat after eachstimulation.
Procedure
Experimentsetup
1.Set up the experiment as shown in the picturebelow.
2.Make sure you have a wash bottle filled with water (or aglass ofwater),acottonpad,fivecards,apenandabottleof alcohol, perfume orcologne.
3.Turn off the air-conditioning system in theroom.
4.You cannot measure emotional responses on yourself.Two students will conduct the experiment while a third studentwill be tested (will be thesubject).
5.Tell the subject to warm his (or her) hands by rubbingthem.
6.Havethesubjectmoistensmallareasontwofingerswitha wet cotton pad.
7.Attach the finger electrodes over these moistened areasas shown in the followingfigure.
8.Tell the subject to sit down. Stand or sit behind him.He should not see you, the other student and thecomputer screen.
Sensorsetup
9.Connect the USBmodule to thePC.
10.Check that the GSR sensor is connected tothe module.
11.Run the Edu-Logger application and check that the GSRsensor is identified.
Settings
11.Click on the On-line Experiment icon in theEdu-Logger main iconbar.
12.Click on the Sensor's Modulebox.
13.Click on the Rangebutton.
14.Select the Arb button to change the sensor's mode(the response in arbitrary numbers is clearer than inɥS).
15.Use the Experiment Setup icon and setthe: Experiment duration to 10minutes
Sampling rate to 10 persecond
Testing andmeasurements
17.Peopledependsoheavilyupontheirsightandhearingthat the action of these senses must minimize beforemaximal attention can be paid to the other sensory inputs.Stimulation bytouchandsmelliseasierwithoutsoundandsight.The sensory organs of touch and smell then becomemore sensitive in theiractivity.
Tell the subject to sit quietly for a few moments with hiseyes closed, head down, legs uncrossed and arms resting onthe supports of an armchair or on his lap. He should not exert any pressure on the fingerelectrodes.
18.Refrain from talking so that the subject will not bestimulated by any external sounds. These conditions should bekept throughout themeasurement.
19.Observethemeasuredresponsevalueinarb.unitsonthe sensor.
This value varies from subject to subject and alsoaccording to the subject's emotioncondition.
20.Click on the GSR sensor module box and set the Y axislimits to be approximately 6000 above and below themeasured value.
21.Onestudentwillperformthestimulationsandtheotherwill document the time of each event and the arbitraryvalue.
22.Click on the Run Experiment icon to startthe measurement.
23.The graph may continue to move up and down. Waitsilently until you get only small changes on thegraph.
24.Event 1: Lightly touch the subject's ear and observethe response on thegraph.
Theproductionofasmallamountofsweatwillcausethe measuredvaluetochange.Themoresweatproduced,the greater thechange.
Note:
There is a time delay between stimulation and aresponse from the sensor. It takes 0.8 to 4 seconds for the handto produce sweat after stimulationoccurs.
25.Event2:Again,stimulatethesubjectbylightlytouchingthe other ear and observe theresponse.
26.Event 3: When the subject becomes habituated totouching, try blowing across the subject's ear or face to see if he orshe responds to airmovements.
Habituation is a decrease in an elicited behaviorresulting from repeatedstimulations.
27.Event 4: Put your hand on the subject'shead.
28.Event 5: Open a bottle of alcohol, cologne or perfumeone meterfromthesubject'snose,allowinghimorhertosmell the aroma. The subject should not know in advance whatyou plan todo.
Theresponsewillletyouknowwhenthesubjectsmellsthe aroma.
29.Save your graph and analyzeit.
LieDetecting
30.Givethesubject5blankcardsandaskhimtowriteaname on eachcard.
One name should be a name of someone that is very closeto him such as his mother, father, brotheretc.
Theotherfournamesshouldbenamesofpeopleheisnot familiar with at all (male or female according to the first name).
31.Prepare the subject for testing as in sections 17-20 anddefine the Y-axis limits asbefore.
32.Scramble the cards and tell the subject to answer 'no'for eachofthefollowingquestionsuntilyoutellhimthatthe experiment is over.
33.Wait at least 15 seconds between questions and askthe subject questions asfollows:
'Is Paul yourbrother?' 'Is Sam yourbrother?' And soon.
34.Observe the subject's response on the graph foreach question.
35.Change the way of questioning, forexample: 'I think that Paul is yourbrother'
'So, Charles is yourbrother'
36.Locate the highest response for a certain name or two names, keep asking in different ways and observethe responses.
37.Tellthesubjectthattheexperimentisoverandselectthe name with the highest response as yourguess.
38.Thisisanexampleofapartofagraphinwhichthesubject was asked a question about the person that he is closeto:
39.Save your graph and analyzeit.
Conclusions
40.Emotionalandsensory(byfiveclassicsenses)stimulation causes the production of sweat. The sweat production ispart of the fight or flightresponse.
41.Wecanseeonthegraphabovethatwhenthesubjectis under stress, sweat is released and can be measured bythe GSR loggersensor.
42.There are a number of areas in the body that havehigh concentrationsofsweatglands,suchastheforehead,the palms of the hand, the arm pits, and the soles of thefeet (measurements of sweat in areas such as the forehead,back or chest are more difficult toobtain).
43.A change in the sweat level occurs 0.8-4 seconds aftera person has beenstimulated.
44.The GSR measurement is included in a polygraph (alie detector). Except for skin conductivity, a polygraph iscapable of measuring changes in blood pressure, pulserate, respiration andothers.
Summaryquestions
1.What can you conclude from yourresults?
2.Except for skin conductivity, a polygraph (lie detector)is capable of simultaneously recording changes inblood pressure, pulse rate and respiration. Explain howthese physiological variables are connected to the fight orflight response; how do they change during acute stress? Howdo these changes help us (or animals) when threat isperceived?
3.Give an example of habituation in animalbehavior.
4.Whichanimalclasshasanabilitytoproducesweat?Point out another unique characteristic of thisclass.