What Is the Law of Initial Values?
The law of initial values (LIV) states that a physiological response’s magnitude is constrained by the current arousal level. If Arousal is already high, the response from that elevated baseline will be smaller than if the same stimulus occurred at a moderate level. This ceiling effect is relevant to interpreting polygraph data from highly anxious examinees.
Significance in PDD
This concept is part of the theoretical and practical framework supporting Deception">psychophysiological detection of deception. Understanding it helps practitioners, researchers, and informed consumers appreciate the scientific foundations of modern polygraph testing and the ongoing refinement of techniques and methods based on empirical research.
Further Reading
For comprehensive information on polygraph science, visit the polygraph glossary, the research database, or the Polygraph Examiner Hub for professional resources.
Professional Context
This concept forms part of the knowledge base expected of qualified forensic psychophysiologists. Training at APA-accredited schools covers the theoretical foundations, practical applications, and research evidence underlying all aspects of polygraph methodology. Ongoing continuing education ensures practitioners stay current with developments in the field.