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Cited by 499Virtual Reality Applications and ImpactsMultisensory perception and integrationFree Will and Agency

The DOI matches its Crossref record; 45 of the 46 references it cites were found in a registry or an index; none of the 40 sources its claims cite is checked for support yet.

Extending Body Space in Immersive Virtual Reality: A Very Long Arm Illusion

Open access
Kilteni, Konstantina, Normand, Jean-Marie, Sanchez-Vives, Maria V., Slater, Mel·2012·PLoS ONE
DOI 10.1371/journal.pone.0040867PMC PMC3400672
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Abstract

Recent studies have shown that a fake body part can be incorporated into human body representation through synchronous multisensory stimulation on the fake and corresponding real body part - the most famous example being the Rubber Hand Illusion. However, the extent to which gross asymmetries in the fake body can be assimilated remains unknown. Participants experienced, through a head-tracked stereo head-mounted display a virtual body coincident with their real body. There were 5 conditions in a between-groups experiment, with 10 participants per condition. In all conditions there was visuo-motor congruence between the real and virtual dominant arm. In an Incongruent condition (I), where the virtual arm length was equal to the real length, there was visuo-tactile incongruence. In four Congruent conditions there was visuo-tactile congruence, but the virtual arm lengths were either equal to (C1), double (C2), triple (C3) or quadruple (C4) the real ones. Questionnaire scores and defensive withdrawal movements in response to a threat showed that the overall level of ownership was high in both C1 and I, and there was no significant difference between these conditions. Additionally, participants experienced ownership over the virtual arm up to three times the length of the real one, and less strongly at four times the length. The illusion did decline, however, with the length of the virtual arm. In the C2-C4 conditions although a measure of proprioceptive drift positively correlated with virtual arm length, there was no correlation between the drift and ownership of the virtual arm, suggesting different underlying mechanisms between ownership and drift. Overall, these findings extend and enrich previous results that multisensory and sensorimotor information can reconstruct our perception of the body shape, size and symmetry even when this is not consistent with normal body proportions.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

In an immersive virtual reality between-groups experiment, participants experienced ownership over a virtual arm elongated up to three times the real arm length, with the illusion declining at four times. Ownership and proprioceptive drift appeared to depend on different underlying mechanisms.

Key findings

  • With no elongation, ownership was high in both congruent (C1) and visuo-tactile incongruent (I) conditions: Q3 median was 4/5 in both, P = 1.0000, while touch-referral Q1/Q2 were significantly higher in C1 (P = 0.0009 and P = 0.0001).
  • Ownership declined with virtual arm elongation: ordered logistic regression of Q3 on elongation had a negative coefficient, P = 0.032; estimated probabilities of Q3 ≥ 4 were 0.86, 0.78, 0.66, and 0.52 for elongations 1–4, leaving about a 50% chance of high ownership at four times real length.
  • Proprioceptive drift was positively associated with elongation (Spearman P = 0.03) and significant in C2 (P = 0.037) and C3 (P = 0.012) but not C4 (P = 0.169); drift did not correlate with ownership, and path analysis suggested different mechanisms.
  • Defensive withdrawal movements to a falling virtual saw were greater during Saw Time than Control Time overall (combined P = 0.017), and hand movement dispersion was positively related to ownership and to feeling harmed.

Methods

  • Fifty participants were assigned to 5 between-groups conditions (n = 10 each): Incongruent (I) and Congruent C1–C4, where the virtual dominant arm was 1, 2, 3, or 4 times the real arm length; mean real arm length was 53 ± 3 cm, giving average C2/C3/C4 lengths of 106, 159, and 212 cm.
  • Participants wore a stereo head-mounted display and saw a first-person virtual body; all conditions had visuo-motor congruence, while visuo-tactile congruence was present in C1–C4 but not I. Elongation occurred over 2 minutes while participants touched a physical box.
  • Measures included a 7-item questionnaire (1–5 scale), proprioceptive drift via angle estimation before and after elongation for C2–C4, and hand-tracking dispersion before and during the virtual saw threat; analyses used nonparametric tests, ordered logistic regression, robust regression, and path analysis.

Limitations

  • The paper states that defensive movements were small because participants were instructed to remain motionless, creating competition between staying still and avoiding the saw; the data likely reflect motor initiation rather than full execution for some participants.
  • The paper states that in C4 the virtual hand was far from the body and visual precision/quality were poorer, and that spatial distance or limits on limb representation may contribute to the illusion decline; it also notes that richer multisensory stimulation may be needed for greater distortions.
  • Evident from the text: each condition had only 10 participants, drift was not measured in C1 or I, and path analysis treated ordinal questionnaire variables as interval-scale, which the paper acknowledges is not strictly justified.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1371/journal.pone.0040867

Cites

45 of 45 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 40 cited sources checked · 0 supported · 0 flagged

Show all 80 claims

  • It may state two separate claims as one. 29
  • Probably not a substantial claim. 17
  • The quote only partly states this claim. 2
45 of 45

  • The authors state this as an assumption.

    The angular drift is 0 at elongation 1 (when the arm is at the same length as the true arm there would be no angular displacement within random error).

    “Although we did not measure angular drift in condition C1 (no elongation but with congruence) we assume that the angular drift is 0 at elongation 1 - that is, when the arm is at the same length as the true arm there would be no angular displacement within random error.”

  • The authors state this as an assumption.

    The questionnaire variables can be treated as if they are on an interval scale for the path analysis.

    “For this purpose we treat all of the questionnaire variables as if on an interval scale.”
2 of 2

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • C1 and C2 hand movements are called significant despite their reported P values

    Major

    The text calls the Saw Time increase significant for C1 and C2, but Table 5 reports two-tailed P values of 0.09 and 0.07. Neither meets the conventional 0.05 significance threshold; the paper elsewhere describes a P value of 0.0914 as a trend.

  • Discussion incorrectly claims significant C3 movement dispersion

    Major

    The discussion says the difference in movement dispersion was significant in C3, whereas Table 5 reports P = 0.72 for C3.

  • Reported fitted ownership at quadruple arm length does not match the path model

    Minor

    Table 7 gives an ownership intercept of 4.489 and an elongation coefficient of −0.341. At elongation 4, these yield 3.125, or about 3.1 to one decimal place, rather than 3.3.

    Reported 3.3 · recomputed 3.125

  • Path-analysis caption reverses the definition of angular drift

    Minor

    The results define AngleDiff as AngleAfter minus AngleBefore, but the Figure 8 caption defines anglediff in the opposite direction.

4 of 4

Citations

Cites

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1 of the 46 references couldn’t be matched to a known paper.

Research works printed but not linked: 1

  1. M Graziano, 2002, How the brain represents the body: insights from neurophysiology and psychology; Hommel WPaB, editor: Oxford: Oxford University Press).

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Metadata

Authors
Kilteni, K., Normand, J.-M., Sanchez-Vives, M. V., & Slater, M.
Affiliations
  • Universitat de Barcelona (ES)
  • Consorci Institut D'Investigacions Biomediques August Pi I Sunyer (ES)
  • Institució Catalana de Recerca i Estudis Avançats (ES)
Corresponding author
Slater, Mel
ORCID
Venue
PLoS ONE
Publisher
Public Library of Science (PLoS)
Published
2012-07-19
Volume
7
Issue
7
Pages
e40867
ISSN
1932-6203 (ISSN-L)
DOI
10.1371/journal.pone.0040867
PMC
PMC3400672
OpenAlex
W1965428772
Semantic Scholar
a6eb124caa6aafcd6bda8c6e524711b90aad993a
Cited by
499
References
46
Citations by year
2026: 26 · 2025: 41 · 2024: 43 · 2023: 32 · 2022: 47 · 2021: 51 · 2020: 64 · 2019: 35 · 2018: 37 · 2017: 31 · 2016: 26 · 2015: 25 · 2014: 26 · 2013: 15
FWCI
38.86
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • RECERCAT (Consorci de Serveis Universitaris de Catalunya) (publishedVersion, other-oa)
  • RePEc: Research Papers in Economics (submittedVersion)
  • Dipòsit Digital de la Universitat de Barcelona (Universitat de Barcelona) (submittedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • UCL Discovery (University College London) (submittedVersion)
  • Figshare (submittedVersion, cc-by)
Funders
FP7 Ideas: European Research Council (227985)
Topics
  • Physical Sciences › Computer Science › Human-Computer Interaction › Virtual Reality Applications and Impacts
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Multisensory perception and integration
  • Social Sciences › Arts and Humanities › Philosophy › Free Will and Agency
Keywords
body ownership, multisensory integration, proprioception, rubber hand illusion, body image, body size perception, immersive virtual reality

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