Human thermal sensitivity drifts at extreme temperatures.

Humans continuously adapt their behavior to ambient temperature, yet little is known about how they integrate distributed thermal sensations into a unified perception.This study investigates how people perceive changes in whole-body thermal environments, particularly under extreme conditions.In a between-subjects design conducted between November 2023 and April 2024, 51 participants compared the temperature felt in four independently controlled climate chambers.To generate meaningful perceptual contrasts, the temperatures varied dynamically within specific ranges: the mild condition involved a cool session (18 6 1 °C) and a warm session (28 6 1 °C), whereas the extreme condition involved a cold session (8 6 2 °C) and a hot one (38 6 2 °C).Results revealed that thermal sensitivity declined under thermal extremes (p < .001),with larger just noticeable difference in cold (0.95 °C) and hot (0.80 °C) compared with cool (0.39 °C) and warm (0.45 °C) sessions.These findings suggest that whole-body thermal sensitivity is disrupted in extreme environments, potentially due to altered sensory integration or perceptual bias, despite the absence of correlation with the physiological states.This dissociation highlights the behavioral limits of human thermoregulation and calls for further investigation into how distributed bodily signals are integrated into unified thermal experiences. Public Significance StatementPeople continuously adjust their behavior in response to ambient temperature, yet it remains unclear how the body integrates distributed thermal signals into a unified sense of warmth or cold.This study shows that temperature sensitivity declines significantly under thermal extremes: Participants were less sensitive to changes when exposed to very cold or very hot environments compared with milder conditions.Interestingly, these changes in perception did not reflect changes in their physiological state, suggesting that the body and mind may not always align when judging temperature.Understanding these perceptual limits can inform the design of buildings, workspaces, and safety guidelines, especially for environments where people may face heat or cold stress.