closed-eyes technique

What Is the Closed-Eyes Technique?

The closed-eyes technique is a procedural variation in polygraph testing where the examinee is instructed to keep their eyes closed during the chart collection phase of the examination. This technique is used to reduce visual distractions, minimise orienting responses to environmental stimuli, and encourage the examinee to focus entirely on the auditory content of the questions being presented.

Purpose and Rationale

The theoretical rationale for the closed-eyes technique is that closing the eyes reduces the amount of external sensory input that could compete with the test questions for the examinee's attention and physiological reactivity. Visual stimuli — movements, lighting changes, objects in the room — can produce orienting responses and non-specific responses unrelated to the test questions, adding noise to the physiological data. By removing visual input, the closed-eyes technique aims to improve the signal-to-noise ratio of the physiological recordings.

Implementation

The examiner instructs the examinee to close their eyes before the chart begins and to keep them closed until instructed to open them after the chart is complete. The instruction is typically given during the pre-test interview as part of the explanation of the testing procedure. Some examiners use the closed-eyes technique routinely, while others use it selectively when an examinee appears visually distracted or produces excessive non-specific responses during initial charts.

Considerations

The closed-eyes technique reduces the examiner's ability to observe the examinee's eye behaviour during testing (such as excessive blinking, focused gaze, or eye movements that might indicate countermeasure activity). It also eliminates the examinee's ability to see the instrument, the room, or the examiner, which some practitioners believe changes the psychological dynamics of the examination. The technique may also increase the risk of drowsiness in very calm or fatigued examinees.

Research Support

Some research suggests that the closed-eyes technique can improve the clarity of physiological responses, particularly in the electrodermal channel, by reducing background noise from visual orienting responses. However, the technique is not universally required by validated techniques, and its use remains a matter of examiner preference and protocol design within the parameters permitted by the technique being used.