What factor contributes to the rapid change of temperature experienced by the experimental subject in the heart rate investigation?

The rapid change of temperature experienced by the experimental subject in the heart rate investigation is primarily influenced by the small volume of water surrounding the subject. When there is a limited amount of water, it has a reduced capacity to absorb and retain heat. This means that any heat generated by the experimental subject can lead to quick and significant temperature changes in the water, thereby affecting the subject’s temperature more rapidly.

In contrast, a larger volume of water would have greater thermal inertia, allowing it to absorb heat without significant changes in temperature. Therefore, the interaction between the small volume of water and the experimental subject significantly enhances the rate at which thermal changes occur, directly impacting the results related to heart rate and temperature feedback in the investigation.