1 The seminal theoretical work on threat detection in humans is The Principles of Psychology by William James, Henry Holt and Company, 1890. While the evidence suggests innate detection mechanisms for snakes, spiders, and angry faces, it is probable that similar detection mechanisms exist for other forms of threatening stimuli.

2 See “Emotion Drives Attention: Detecting the Snake in the Grass” by Arne Öhman, Anders Flykt, and Francisco Esteve, Journal of Experimental Psychology: General, September 2001, vol. 130(3), p. 466–478; and “Finding the Face in the Crowd: An Anger Superiority Effect” by Christine H. Hansen and Ranald D. Hansen, Journal of Personality and Social Psychology, 1988, vol. 54, p. 917–924.

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