Heart Is Deceitful Above All Things: illusory perception of heartbeat is induced by pain expectation

Abstract

AbstractOur interoceptive states and their perception are thought to be heavily shaped by interactions between expectations and interoceptive information. Surprisingly, previous research mostly investigated the impact of expectations on interoceptive states themselves (i.e. cardiac activity), rather than the perception of these states (i.e. heartbeat perception).This study investigated whether expectations of pain induce an illusory perception of heartbeat frequency, so that heartbeat perception reflects expectations about how the heartbeat will change, rather than only the actual change. Participants were instructed to report continuously their heartbeat, either tapping along to it (i.e., Experiment 1, heartbeat tapping task) or silently counting (i.e., Experiment 2, heartbeat counting task), while ECG was recorded. Crucially, while completing this task, subjects were presented with two types of cues, which provided valid predictive information about the intensity of an upcoming cutaneous stimulation, that is a high- or low- pain electrical stimulus. Results showed that, whenever participants were exposed to cues that signalled the upcoming high-painful stimulation, they reported a higher number of heartbeats compared to when they were anticipating a low-painful shock. Importantly, the perceived increase was not mirrored by the real cardiac frequency, which showed no difference when participants were anticipating a high- vs. low- pain stimulus. Moreover, such perceptual modulations were dramatically reduced when participants executed the same tapping task but with an exteroceptive visual stimulus (i.e., Experiment 3, exteroceptive tapping task). Together, the findings reveal, for the first time, a perceptual illusion of heartbeats associated to pain expectation. This study offers some important insights for understanding how inferential processes can actively generate interoceptive perception, emphasizing its pivotal role within the predictive aspects of the processing of bodily signals and of physiological regulation.