The sense of body ownership represents a fundamental aspect of bodily self-consciousness.
Using multisensory integration paradigms, recent studies have shown that both exteroceptive
and interoceptive information contribute to our sense of body ownership. Interoception
refers to the physiological sense of the condition of the body, including afferent
signals that originate inside the body and outside the body. However, it remains unclear
whether individual sensitivity to interoceptive modalities is unitary or differs between
modalities. It is also unclear whether the effect of interoceptive information on
body ownership is caused by exteroceptive 'visual capture' of these modalities, or
by bottom-up processing of interoceptive information. This study aimed to test these
questions in two separate samples. In the first experiment (N = 76), we examined the
relationship between two different interoceptive modalities, namely cardiac awareness
based on a heartbeat counting task, and affective touch perception based on stimulation
of a specialized C tactile (CT) afferent system. This is an interoceptive modality
of affective and social significance. In a second experiment (N = 63), we explored
whether 'off-line' trait interoceptive sensitivity based on a heartbeat counting task
would modulate the extent to which CT affective touch influences the multisensory
process during the rubber hand illusion (RHI). We found that affective touch enhanced
the subjective experience of body ownership during the RHI. Nevertheless, interoceptive
sensitivity, as measured by a heartbeat counting task, did not modulate this effect,
nor did it relate to the perception of ownership or of CT-optimal affective touch
more generally. By contrast, this trait measure of interoceptive sensitivity appeared
most relevant when the multisensory context of interoception was ambiguous, suggesting
that the perception of interoceptive signals and their effects on body ownership may
depend on individual abilities to regulate the balance of interoception and exteroception
in given contexts.