The fight-or-flight response, first identified by Walter Cannon, is the body's primary physiological reaction to a perceived threat. This response involves the coordinated activity of both the sympathetic nervous system and the hypothalamic-pituitary-adrenal (HPA) axis. This built-in adaptive mechanism prepares an individual to either confront or escape a danger, thereby increasing the chances of survival by helping to maintain homeostasis.

Fight or Flight Response

Walter Cannon's theory posits that in response to a perceived threat, the body activates the sympathetic nervous system, triggering a cascade of physiological changes. Cannon viewed this response as a fundamental, built-in mechanism for maintaining homeostasis, the body's stable internal environment. He considered it an adaptive function that prepares an individual to either fight or flee, enabling them to adjust to environmental threats and ultimately enhance their chances of survival.

Cannon's Fight or Flight Response Theory

Walter Cannon was an eminent American physiologist at Harvard Medical School and an early pioneer in the study of stress. In the early 20th century, he was the first to identify the body's fundamental physiological reactions to stressful events, which formed the basis for his later theory of the fight-or-flight response.

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Trinity College (CT)

Contributors to Stress Research and Understanding

Spielman, R. M., Jenkins, W. J., & Lovett, M. D. (2020, April 22). Psychology (2nd ed.). OpenStax. https://openstax.org/books/psychology-2e/pages/1-introduction

OpenStax Psychology (2nd ed.) Textbook

Walter Cannon

Hans Selye, who became one of the world's leading experts on stress, made a foundational discovery in the 1930s while working at McGill University. His research, originally focused on sex hormones in rats, took an unexpected turn when he observed that prolonged exposure to various negative stimuli—including extreme cold, surgical injury, excessive exercise, and shock—produced a consistent set of physiological changes. These changes included adrenal enlargement, shrinkage of the thymus and lymph nodes, and stomach ulceration. This accidental finding led him to identify and develop the theory of the General Adaptation Syndrome.

Hans Selye

Robert Sapolsky is a prominent researcher known for his work in the field of stress, as referenced in his 1998 publication.

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