A cardio-visual full body illusion improves body size estimation in healthy women

Einleitung Body image distortion (BID), i.e., the misestimation of one's own
body size, is found in healthy women, and presents a risk factor for the development
of eating disorders. According to the allocentric lock hypothesis, BID
is the result of experiencing the body from an allocentric perspective, compared
to egocentric perspective. BID has been linked to interoceptive deficits and
can be improved by visuotactile body illusions.
Methoden We investigated the effects of a cardio-visual full body illusion (cv-
FBI) on BID in 45 healthy women. The cvFBI was induced by presenting a 3D
body scan of the participant in VR, flashing with a short (230ms) or long
(530ms) delay after the R-peak of the participant's ECG, or not flashing at all.
The same conditions (short delay, long delay, no flash) combined with a 3D
object (cube) served as control conditions. Before and after each illusion condition
participants performed an egocentric body size estimation task (width
and circumference estimations of different body parts), and an allocentric body
size estimation task in VR (adjusting the distorted 3D body to the perceived
body size).
Ergebnisse The results show a significant change in egocentric body size estimations,
irrespective of cardio-visual feedback or VR content. No change in
size estimations could be found in the allocentric body size estimations.
Schlussfolgerung These results demonstrate that egocentric body representations
are malleable, while allocentric body representations are stable, lending
support to the allocentric lock hypothesis. This study offers new implications
for interventions to target BID in healthy women and women with eating disorders.