Interoception involves the processing of internal bodily signals in the brain and sensations that arise from this process. Consequently, interoception plays a role in various cognitive functions. This concept has gained attention for its potential causal role in cognitive processes, with recent research methods focusing on utilizing periodic physiological activity and methods employing vagus nerve stimulation (VNS) to further explore this role. This study focuses on two specific approaches: periodic activity of the heart and noninvasive transcutaneous VNS. It investigates the physiological activities underlying these methodologies, outlines how experiments can be designed, reviews related studies, and discusses the challenges associated with both research methods. The findings provide an understanding of these two methods of investigating the causal role of interoception.