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LIT-1267: Reply to: No specific relationship between hypnotic suggestibility and the rubber hand illusion

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StatusActive — read 2026-10-20 (NOTE-1003) in full; worth reading as the clearest short statement of why a synchronous-minus-asynchronous difference cannot by itself show that the rubber hand illusion is multisensory: participants expect more from the synchronous condition, and in Lush et al.'s sample (n = 353) that expectancy difference did not vary with hypnotisability, so a null relation between hypnotisability and the synchrony effect is what demand characteristics predict too. It adds that agreement with the ownership item rises steeply with hypnotisability (b = 0.76 per SWASH point) and reaches minimal agreement only in the top 31%. Read it as a reply: the expectancy and ownership regressions are post hoc, as the authors grant of both sides, and its alternative for low-suggestible participants, response bias, is asserted and not measured.
Tagsself, psychometrics, neuroscience, embodied-cognition, philosophy-of-science
RivalsLIT-1264 — No specific relationship between hypnotic suggestibility and the rubber hand illusion
Cited as “paper” byNOTE-1003 — Lush & Seth — Reply to: No specific relationship between hypnotic suggestibility and the rubber hand illusion
Cited as “source” byTHEORY-766 — Brushing a seen rubber hand in synchrony with the hidden real hand, against asynchronous brushing, raises reports that touch is felt at the rubber hand and, more weakly and less reliably, that the rubber hand is one's own; the proprioceptive drift toward the rubber hand that accompanies these reports is not a measure of them; the standard comparison conditions do not equalise participants' expectations, so whether the stimulation or the expectation produces the report difference is open

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Lush, P. & Seth, A. K. (2022). Reply to: No specific relationship between hypnotic suggestibility and the rubber hand illusion. Nature Communications 13, 563. DOI 10.1038/s41467-022-28178-y. Reply to Ehrsson et al. (2022), Nat Commun 13, 564.

Key takeaways

From the reading, NOTE-1003.

  • The disagreement is interpretation, not data. The authors accept Ehrsson et al.’s null relation between hypnotisability and the synchrony effect as a replication of their own, and call the drift reanalysis insensitive.
  • The asynchronous condition is not a control for expectation. Participants expect more from synchronous stimulation, so the difference between conditions confounds timing with demand. In the target sample the expectancy difference did not vary with hypnotisability (b = -0.16, SE 0.09, P = 0.072, B = 0.07), which by their account explains the null.
  • Two routes to the same report. The proposal is that participants high in phenomenological control meet the demand by having the experience, and those low in it by response bias or compliance. Low suggestibles’ residual illusion is put down to the second route.
  • Ownership is the weak item. Mean agreement was 1.9 and 1.2 for the two referred-touch items and 0.7 for ownership (seven-point scale, maximum 3); ownership agreement rose 0.76 points per SWASH point and reaches 1 only above SWASH 2, the top 31%.
  • Implicit measures are not exempt. Expectancies cover drift and skin conductance as well, by the authors’ cited work, and could cover 2AFC and cross-modal congruency tasks, which have not been tested for it.

Standing in the record

Filed on 2026-10-20 at the owner’s request for experimental work building on the rubber hand illusion, with the comment it answers, Ehrsson et al. 2022 (LIT-1264), declared as its rival reading of the same data. The target article, Lush et al. 2020, Lush’s 2020 Collabra paper and Roseboom & Lush 2022 are being filed alongside. Read in full: Active.

It does more to THEORY-765 than the comment it answers. That THEORY’s promote_when accepts either expectations measured or matched, or trait suggestibility measured with the synchrony effect surviving it. This reply shows, with data, that the second can be met while the first fails, and that its authors’ account predicts exactly that. The NOTE proposes tightening the promote_when, and sets out the bearing on the other three rubber-hand THEORYs.

Anil Seth, its second author, wrote Seth 2013 (LIT-1263), the source of THEORY-767, whose cardio-visual evidence is a synchronous against asynchronous comparison of the kind this reply says “offers no protection against demand characteristic effects”. Manos Tsakiris, of Apps & Tsakiris 2014 (LIT-1262), is on the other side, an author of the comment.

One of the sources of THEORY-766 (filed 2026-10-20), which restates the rubber hand synchrony effect as a difference in reports, separates drift from those reports, and leaves open whether expectation produces the difference.

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