[Evaluating the validity of short witness reports using behavioral and psychophysiologic parameters]

Within the context of credibility assessment, the impact of behavioral and physiological adaptation and response patterns of truly and falsely testifying eyewitnesses was examined in a laboratory study. It was further examined statements concerning characteristics of the delict and the experimental situation itself. 20 subjects were instructed to truly or falsely testify after having witnessed a willful destruction. Eye movements, respiration, heart rate and skin conductance were recorded and analyzed by computer. Witnesses instructed to falsely testify showed elevated skin conductance responses and an increased variability of horizontal eye movements at the beginning of the session. Additionally, they also showed stronger responses in eye-blink rate, respiration rate and variability of skin conductance and heart rate to questions related to the behavior in the experimental situation. Reactivity to questions concerning the culprit was less pronounced. Results are discussed in terms of their application within the German law system.