Cold pressor test

An acute-stress induction, not an interoceptive measurement — catalogued here because the wiki’s stress-and-interoception studies use it as their independent variable, and because its side effects bear directly on how their results should be read.

What it does

Immersing a hand in near-freezing water for a few minutes produces a rapid, reproducible autonomic stress response: heart rate and blood pressure climb within the immersion window and recover over the following minutes. The socially-evaluated variant (SECPT — an observer plus a camera during immersion) adds a psychosocial-evaluative component that recruits the HPA axis, so cortisol rises too. This makes it a fuller model of stress than pure arousal manipulations (caffeine, exercise) while being far more standardized in timing than the Trier Social Stress Test.

Why it is dangerous to pair with cardiac interoception

The very thing that makes it a good stressor — sympathetic drive raising cardiac contractility — also makes the heartbeat a louder mechanical signal, and a louder heart is easier to detect for reasons that have nothing to do with perceptual ability. In Schulz et al. (2013) the CP raised heart rate +8.2 bpm and systolic pressure +20.6 mmHg, and heartbeat-counting accuracy rose in lockstep — a result the authors read (and flag as unproven, because stroke volume went unmeasured) as the cardiodynamic confound rather than sharpened interoception. Add the cold-specific vascular effects and the nociceptive load, and any post-CP change on a cardiac task has several candidate causes the manipulation cannot separate. The lesson generalizes: a stressor that moves the signal is a poor way to test whether stress moves the perceiver.