Advantages and disadvantages of using polygraphs in criminal investigations
Have you ever wondered how the polygraph works and whether it is a reliable tool in criminal investigations? In this article we will explore the advantages and disadvantages of using the polygraph, also known as the truth machine, in such situations.
Advantages of the use of polygraph in criminal investigations:
1. Helps to detect signs of stress and deception: The polygraph measures the subject's physiological response, such as heart rate, blood pressure and skin conductance, among other parameters. These changes can indicate whether someone is lying or under stress, which can be useful for identifying suspects in criminal investigations.
2. It can provide new lines of research: In some cases, the results of the polygraph can open new lines of investigation or confirm existing suspicions. This can help investigators to focus their efforts on specific individuals or areas, which can speed up the process of solving cases.
3. Can be used as an interrogation technique: Although the polygraph is not infallible, its use can be used as an effective interrogation technique. The presence of the machine can influence the subject's behaviour, making them more likely to reveal information or confess to a crime.
Disadvantages of polygraph use in criminal investigations:
1. No test is infallible: like any method, the polygraph has a margin of error. Even so, its validated techniques reach an accuracy of 85-90% according to the American Polygraph Association, which is why it is used as supporting evidence —never as the only proof—, always interpreted by a qualified examiner who keeps false positives to a minimum.
2. Can be influenced by external factors: The result of the polygraph can can be affected by external factors such as stress, anxiety or medication that the individual is taking. These elements can trigger physiological responses similar to those of cheating, making it difficult to accurately interpret the results.
3. Not legally admissible in all countries: Although the use of the polygraph may be common in some countries, not all legal systems consider it a valid test in court. This is due to the lack of scientific consensus on its reliability and possible errors in the interpretation of the results.
The polygraph can be a useful tool in criminal investigations, as it can detect signs of stress and deception, provide new lines of investigation and be used as an interrogation technique. However, it also has disadvantages, such as its lack of absolute accuracy, the influence of external factors and its lack of legal acceptance in some countries. It is important to consider all these advantages and disadvantages when using the polygraph in the field of justice.
Read more about frequently asked questions related to polygraphs
In conclusion
The polygraph can be a useful tool in criminal investigations, as it can provide valuable information and assist investigators in their work. However, it is important to be aware of its limitations and not to rely solely on polygraph results to make important decisions. It is important to complement the use of the polygraph with other more reliable investigative techniques and tests. Each case and situation is unique, so it is critical to carefully evaluate the use of the polygraph in each specific context. Remember, the truth can sometimes be more complex than it appears at first glance.