Visual information without thermal energy may induce thermoregulatory-like cardiovascular responses.

Background: Human core body temperature is kept quasi-constant regardless of varying thermal environments. It is well known that physiological thermoregulatory systems are under the control of central and peripheral sensory organs that are sensitive to thermal energy. If these systems wrongly respond to non-thermal stimuli, it may disturb human homeostasis.
Methods: Fifteen participants viewed video images evoking hot or cold impressions in a thermally constant environment. Cardiovascular indices were recorded during the experiments. Correlations between the 'hot-cold' impression scores and cardiovascular indices were calculated.
Results: The changes of heart rate, cardiac output, and total peripheral resistance were significantly correlated with the 'hot-cold' impression scores, and the tendencies were similar to those in actual thermal environments corresponding to the impressions.
Conclusions: The present results suggest that visual information without any thermal energy can affect physiological thermoregulatory systems at least superficially. To avoid such 'virtual' environments disturbing human homeostasis, further study and more attention are needed.