From hands to heart: a trend for higher interoceptive accuracy in left-handed as compared to right-handed female participants

There is a discrete anatomical organization of the neural substrates of mental processes. Right
hemispheric dominance was repeatedly shown for interoception, the perception and processing
of signals from inside the body. This right hemispheric dominance is supported, for example,
by stronger heartbeat-evoked potentials (HEPs) over the right hemisphere, which represent
neurophysiological indicators of cardiac interoception. These findings, however, are based on
individuals with left hemispheric dominance, which manifests among other traits, predominantly in
right-handedness. Left-handed individuals (presumably showing a right-hemispheric dominance)
may show a facilitation of processes with a right-hemispheric relevance, such as interoception,
which remains yet unclear. N = 42 healthy participants (21 left- and right-handed each) performed
the heartbeat counting task (HCT) to assess cardiac interoceptive accuracy (“IAc”, i.e. the
correspondence between actual and perceived bodily signals), as well as a time estimation task, as
previous studies suggested that IAc in the HCT may be confounded by time estimation accuracy
(TEAc). We found a trend-level difference among female participants, with left-handers presenting
higher IAc scores than right-handers. There were no differences in TEAc or heart rate between
groups. These preliminary findings suggest a potential facilitating effect of right hemispheric
dominance on interoception, which seems to be specific for additional hemispheric specialization
effects related to female sex. Future studies are warranted to replicate this trend and to reveal
neurophysiological mechanisms of this effect (e.g., by investigating HEPs).