1.1.2 - Investigative Interviews and Physiological Responses

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[00:00:00]everybody this is a quick video over polygraph tests and physiological responses for the beginning of 1.1.2 reliable Witnesses so in this activity you're going to get introduced to five Persons of Interest in the anag Garcia case and you're going to get a chance to evaluate their polygraph data from interviews that they had with Law Enforcement Officers investigating this case to try to determine if any of them might be lying uh in their responses so we don't know a lot about the case yet with an Garcia but if there is foul play these five people uh had a close relationship with Anna and they were there for um more likely to have been involved and so those five people are first Eric pedmont uh Eric pedmont is uh Anna's boyfriend he's 20 years old and Friends noted that Anna and Eric were recently seen arguing Dominique Hall is Anna's classmate they're kind of like friendly Rivals they're in classes together but they kind of compete with each other quite a bit Taylor Diaz uh 19 years old and his friend who actually found her in the lab he works with Anna in the lab uh he's the one who actually called police Dr opal it is her lab that Anna Works in uh she is Anna's adviser um and recently declined to write a recommendation letter for her and then finally Sam green and a soccer teammate they do not get along very well they really don't seem to like each other and they've been seen fighting um recently and arguing about soccer stuff all right so like I said you're going to get a chance to look at their polygraph data but first we have to learn more about a polygraph and what it is so in frenic investigations polygraph tests which are also known as a lie detector tests you heard of lie detector tests that's what we're talking about these are sometimes used to help determine the truthfulness of someone's testimony now importantly polygraph tests are not 100% reliable in detecting lies okay when we see changes in a polygraph test those indicate that somebody might be lying the reasons for that are because when somebody lies they have changes in their physiological responses usually not always some people are really good liars and so some people can lie and not have any physiological responses likewise you can also have a lot of false positives people can have changes in their physiological responses due to other factors that might not be them lying right think about anybody who's being interviewed here right um if they're they're being asked questions about their dead friend right that can cause an emotional response emotional responses other than lying can also cause changes of physiological responses so keep that in mind uh there's going to be an ethical scenario that you look into later all about admissibility of polygraph tests in court uh so what is a polygraph test well the prefix poly poly means multiple right that is a prefix meaning multiple or many uh and so we are graphing many physiological responses so this physiological responses that are usually included in a polygraph test are heart rate blood pressure respiration rate and skin conductivity heart rate of course is just number of cardiac cycles per minute usually registered in beats per minute blood pressure um this is in measured in millimeters of mercury and we're going to talk a lot more about that uh in a future unit blood pressure is just the pressure that is exerted by the blood on the walls of the blood vessels respiration rate how many breaths per minute somebody is taking right how frequently how quickly they're breathing and then skin conductivity uh this is something that is measured that is um used as a proxy for or an approximation of the amount that somebody's sweating when somebody sweats it interferes with their Skin's ability to conduct elect electricity and so changes in skin conductivity could indicate somebody's sweating and sweating is also possibly an indication somebody might be lying because when people lie they get stressed out and generally and they might start sweating so that's a little bit of a preview there of polygraph tests and physiological data