The ability to sense the internal state of one's body is the process of interoception and is a marker for positive emotional outcomes. The last five years have seen burgeoning research interest in interoception, including a call for more integrative and predictive biomarkers for interoceptive ability. While there is a robust literature purporting to measure interoception, there is also significant research challenging the content validity of the current methodology. Beyond these published challenges, I offer a broader critique that suggests that the current reductionist approach fails to capture the integrative nature of interoception. I introduce an alternate methodology to assess interoceptive ability that leverages the integrative nature of the autonomic nervous system. Thirty-four undergraduates provided real-time feedback about their subjective state of arousal while watching three videos of varying intensity. Across subjects, arousal feedback did not positively correlate with physiological indices of sympathetic arousal including electrodermal activity and the inverse of pre-ejection period. However, each subject appeared to have an idiographic pattern of physiological variables that correlated strongly, although often negatively, with the subjective slider feedback. These physiological patterns provide the foundation for investigating a new biomarker for interoception that relies on the autonomic nervous system to surmise interoceptive states. / Doctor of Philosophy / A person's sense of their body is called interoception. Research has shown that people who are good at interoception tend to live happier and more fulfilling lives. But current research techniques don't do a great job measuring whether someone is good at interoception. These techniques have faced a lot of criticism for the errors they are known to make. I add my concerns that the current techniques don't reflect how we naturally sense into our bodies when we're not in a lab. I explain why I think we need a new way of measuring interoception that captures how holistic this process is. I introduce a new measure that is based on the energy in our body. I believe that people use this energy system naturally and will also be better able to reflect this is a lab setting. The people in this study used a slider dial to indicate how much energy they felt while they watched videos with different excitement levels. While they watched the videos and moved the dial, we measured their bodily readings from their heart, breathing, and sweat to see if these readings matched their dial ratings. We were surprised that the typical body readings for excitement were not directly related to the slider movements when we averaged across people, but we did find that each person had their own unique way of responding that was similar in both mind and body. This research is the basis for a new way to understand how people read their own body, and how accurate this reading is.