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Why do scientists prefer the term tonic immobility over playing dead?

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A fluffy gray cat clings to the trunk of a tree, looking upward as it climbs to escape. — Avoidance behaviour Cat fleeing by upward climbing.

Scientists prefer the term tonic immobility over "playing dead" or "death feigning" because it is a neutral, scientific descriptor that avoids making unproven assumptions about an animal's internal state or intentions.1

While terms like "playing dead" imply that an animal is making a conscious, deliberate choice to deceive a predator, research has not yet confirmed that all animals enter this state purposefully. Furthermore, it remains unclear whether predators actually perceive the prey as dead when they encounter this behavior.1

By contrast, tonic immobility accurately describes the observed behavioral state as an unlearned, reflexive, and reversible condition characterized by extreme motor inhibition. This terminology avoids anthropomorphizing the animal's actions and does not rely on subjective interpretations regarding the animal's goals or the predator's perception.21