The rubber foot illusion.
BACKGROUND
Lower-limb amputation causes the individual a huge functional impairment due to the lack of adequate sensory perception from the missing limb. The development of an augmenting sensory feedback device able to restore some of the missing information from the amputated limb may improve embodiment, control and acceptability of the prosthesis.


RESULTS
In this work we transferred the Rubber Hand Illusion paradigm to the lower limb. We investigated the possibility of promoting body ownership of a fake foot, in a series of experiments fashioned after the RHI using matched or mismatched (vibrotactile) stimulation. The results, collected from 19 healthy subjects, demonstrated that it is possible to elicit the perception of possessing a rubber foot when modality-matched stimulations are provided synchronously on the biological foot and to the corresponding rubber foot areas. Results also proved that it is possible to enhance the illusion even with modality-mismatched stimulation, even though illusion was lower than in case of modality-matched stimulation.


CONCLUSIONS
We demonstrated the possibility of promoting a Rubber Foot Illusion with both matched and mismatched stimulation.
The BioRobotics Institute, Scuola Superiore Sant'Anna, viale Rinaldo Piaggio, Pontedera (PI), Italy. s.crea@sssup.it.
Simona
S
Crea
The BioRobotics Institute, Scuola Superiore Sant'Anna, viale Rinaldo Piaggio, Pontedera (PI), Italy. m.dalonzo@sssup.it.
Marco
M
D'Alonzo
The BioRobotics Institute, Scuola Superiore Sant'Anna, viale Rinaldo Piaggio, Pontedera (PI), Italy. n.vitiello@sssup.it.|Don Carlo Gnocchi Foundation, via di Scandicci, Firenze (FI), 269, Italy. n.vitiello@sssup.it.
Nicola
N
Vitiello
The BioRobotics Institute, Scuola Superiore Sant'Anna, viale Rinaldo Piaggio, Pontedera (PI), Italy. ch.cipriani@sssup.it.
Christian
C
Cipriani
D000328:Adult; D000671:Amputation, Surgical / Q000523:psychology*; D000674:Amputees / Q000523:psychology; D001186:Artificial Limbs; D001676:Biofeedback, Psychology; D001828:Body Image; D005260:Female; D005528:Foot; D064368:Healthy Volunteers; D006801:Humans; D007088:Illusions / Q000209:etiology / Q000523:psychology*; D035002:Lower Extremity / Q000293:injuries / Q000601:surgery; D008297:Male; D010812:Physical Stimulation; D012649:Self Concept