An interoceptive illusion of effort induced by false heart rate feedback

Interoception, or the sense of the internal state of the body, is key totheadaptiveregulationofourphysiologicalneeds.Recenttheories contextualize interception within a predictive coding framework, according to which the brain both estimates and controls homeostatic and physiological variables, such as hunger, thirst, and effort levels, by orchestrating sensory, proprioceptive, and interoceptive signalsfrominsidethebody.Thisframeworksuggeststhatproviding false interoceptive feedback may induce misperceptions of physiological variables, or “interoceptive illusions.” Here we ask whether it is possible to produce an illusory perception of effort by giving participants false acoustic feedback about their heart rate frequency during an effortful cycling task. We found that participants reported higher levels of perceived effort when their heart rate feedback was faster compared with whenthey cycled at the same levelof intensity witha veridicalfeedback.However, participants didnot reportlower effort when their heart rate feedback was slower, which is reassuring, given that failing to notice one’s own effort is dangerous in ecologically valid conditions. Our results demonstrate that false cardiac feedback can produce interoceptive illusions. Furthermore, our results pave the way for novel experimental manipulations that use illusions to study interoceptive processing.