Comparison of methods: Polygraph and non-verbal behavioural analysis
Have you ever wondered how lie detection techniques work? Today we are going to look at two of the most popular methods: the polygraph and non-verbal behavioural analysis. But which method is more effective?
What is the polygraph?
The polygraph, commonly known as the 'truth machine', is a device that records a person's physiological responses when asked questions. The idea is that if you lie, your body experiences certain changes that the machine can detect, such as an increase in blood pressure or heart rate. The polygraph test has been used for decades in different contexts, from criminal justice to television programmes.
What is non-verbal behaviour analysis?
Non-verbal behaviour analysis, on the other hand, is based on interpreting the unconscious signals we give off when we are nervous or when we lie. This can include everything from facial micro-expressions to body position and hand gestures.
Comparing polygraph and non-verbal behavioural analysis
Although both methods have their advocates, there are significant differences in their use and effectiveness. While the polygraph focuses on physiological responses, non-verbal behavioural analysis examines bodily communication and emotional reactions.
The effectiveness of the polygraph
The polygraph has been criticised for being vulnerable to cross-examination tactics. For example, a person who is nervous, even if they are telling the truth, may trigger similar responses to someone who is lying. In addition, people who are particularly calm or who have been trained to control their physiological responses may fool the machine.
Effectiveness of non-verbal behaviour analysis
Non-verbal behaviour analysis has the benefit of being able to be used in situations where the polygraph is not practical, such as in a natural conversation or during a negotiation. However, it also has its limitations, as not everyone expresses nervousness or deception in the same way, and it can be affected by observer bias.
Conclusion: Polygraph vs. non-verbal behavioural analysis
Both methods can be useful, but they also have their limitations. The effectiveness of these methods can vary greatly from person to person, so it is important to always use them with caution and not rely solely on them to identify the truth.
