The Influence of Tongue Biting on Polygraph Responses: An Experimental Approach to Evaluating Countermeasures

Polygraph testing remains widely used in forensic investigations to detect deception through physiological responses, yet its reliability is challenged by countermeasures. This study investigated tongue biting as a physiological countermeasure under the Concealed Information Test (CIT) among participants aged 18–25. Physiological responses, including Electrodermal Activity (EDA), respiration, cardiograph signals, and Relative Response Magnitude (RRM), were analysed using paired-samples t-tests. Tongue biting produced significant increases in EDA and RRM, generating response patterns resembling deception, while respiration and heart rate remained unaffected. The findings demonstrate that even subtle countermeasures can compromise polygraph accuracy, highlighting the need for improved detection methods.