Question

A polygraph (lie detector) works by: A. monitoring physiological indices of autonomic arousal. B. directly assessing the truthfulness of a person's statements. C. monitoring the person's facial expressions. D. all of the above.

Short answer

Answer: A. monitoring physiological indices of autonomic arousal.

Step-by-step solution

Analyze the answer choices

To determine the correct answer, let's examine each choice and discuss its validity. A. A polygraph does monitor physiological indices such as heart rate, blood pressure, and respiration, which can indicate autonomic arousal when a person is lying. This option is valid. B. A polygraph indirectly assesses the truthfulness of a person's statements by measuring physiological responses which can be indicative of lying, though it doesn't measure truthfulness directly. This option is not entirely correct. C. Although facial expressions can be helpful in detecting lies, a polygraph primarily relies on physiological responses and doesn't solely monitor facial expressions. This option is not correct. D. All of the above - This option suggests that a polygraph works through all three methods mentioned. Since B and C are not entirely correct, this option is also not correct.

Choose the correct answer

As we have analyzed all the options and found A to be the most valid answer, the correct answer for this exercise is: A. monitoring physiological indices of autonomic arousal.

Key concepts

Autonomic Arousal

Autonomic arousal refers to the activation of the autonomic nervous system. This system is responsible for regulating involuntary body functions, such as heart rate and breathing. When people lie, their bodies can involuntarily respond, creating a state of heightened arousal.
A polygraph measures this response by detecting changes in physiological states. These involuntary responses occur because lying can be stressful or anxiety-inducing for many people. For instance:

• Increased heart rate
• Elevated blood pressure
• Faster respiration rate
• Increased sweat gland activity

These physiological changes are tracked by the polygraph, which helps in identifying autonomic arousal associated with deception.

Physiological Indices

Physiological indices are the measurable bodily responses that can be observed and recorded during a polygraph test. The goal is to assess physical changes that occur when a person undergoes stress, such as lying.
The main physiological indices that a polygraph monitors include:

• Heart rate: Changes here can indicate a stress response.
• Blood pressure: This can rise due to stress or anxiety.
• Respiration: Shallow or rapid breathing can signify nervousness.
• Galvanic skin response: Sweat gland activity increases with stress, which affects the skin's electrical conductance.

By analyzing these indices, the polygraph attempts to infer whether the person might be lying. However, it's important to note that these changes can occur due to various reasons and not just deception.

Lie Detection

Lie detection is the process of determining whether someone is telling the truth or a lie. While the polygraph is a well-known tool for this purpose, it doesn't offer definitive results. Instead, it measures the physiological responses, as previously mentioned, that might be associated with lying.
Here's a basic idea of how lie detection via a polygraph works:

• The subject is hooked up to the polygraph machine.
• A baseline is established by asking simple, non-threatening questions to gauge normal physiological responses.
• Relevant questions are intermixed with control questions during the examination, observing any physiological changes.
• Significant deviations from the baseline during relevant questions might indicate a lie.

While polygraphs can signal potential deception, factors like nervousness, fear, or other emotions can also cause these physiological changes, which is why the results are not deemed 100% accurate in lie detection.