homeostasis

What Is Homeostasis?

Homeostasis is the body's tendency to maintain a stable internal environment — keeping physiological variables such as body temperature, blood pH, blood glucose, blood pressure, and heart rate within narrow functional ranges. In polygraph science, homeostasis is relevant because the physiological responses the polygraph measures represent temporary departures from the homeostatic state — disruptions caused by the autonomic nervous system's activation in response to psychologically significant stimuli.

Homeostasis and the Polygraph Response

When a deceptive examinee hears a threatening relevant question, the sympathetic nervous system disrupts homeostasis — increasing skin conductance, altering breathing patterns, raising blood pressure. After the threatening stimulus passes, homeostatic mechanisms work to restore the resting state. The recovery time — how quickly the examinee returns to baseline after a response — is itself a scoring feature in some methodologies.

Related Concepts

Allostasis — the process of achieving stability through physiological change — extends the homeostasis concept. The baseline established during polygraph testing represents the examinee's homeostatic set point for the examination session, against which question-related departures are evaluated. The law of initial values describes how the pre-stimulus homeostatic state influences the magnitude of the response.