"The heart is unreliable because its affected by not only by your brain, but by many other factors, such as hormones. The gut has a mind of its own —literally. It has its own well-developed nervous system that acts independently of almost everything except your unconscious brain."Quoted is "Pankaj Pasricha, leader of a research team that thinks stomach activity may be a better indicator than heart rate in the iffy science of lie detection."
It reminded me of an earlier statement made about the trustworthiness of the heart. It says, "The heart is deceitful above all things, And desperately sick; Who can understand it?" It goes on to say, "I, the Lord, search the heart and test the mind, to give every man according to his ways, according to the fruit of his deeds." This is from the book of the prophet Jeremiah, chapter 17, verses 9 and 10.
(Actually, in the Hebrew it is "the kidneys" that the Lord "tests." Know why?)