scholarly journals Demand characteristics confound asynchronous control conditions in indirect measures of the rubber hand illusion.

2021 ◽  
Author(s):  
Peter Lush ◽  
Anil Seth ◽  
Zoltan Dienes
Keyword(s):  
Subjective Experience ◽  
Visual Stimulation ◽  
Control Measures ◽  
Rubber Hand Illusion ◽  
Rubber Hand ◽  
Subjective Report ◽  
Demand Characteristics ◽  
Asynchronous Control ◽  
Indirect Measures ◽  
Body Location

Reports of experiences of ownership of a fake hand following synchronous tactile and visual stimulation of fake and real hands have been attributed to multisensory integration mechanisms (the rubber hand ‘illusion’). However, it has been shown that the subjective reports expected, namely stronger experiences in the synchronous than asynchronous condition, and for ‘illusion’ rather than ‘control’ statements, are clear to subjects; thus, the reports may reflect response to demand characteristics. Subjective report is often accompanied by so-called ‘objective’ or ‘implicit’ measures. Like subjective report, an asynchronous control condition is typically employed for these measures. Here we report tests of expectancies for synchronous ‘illusion’ and asynchronous ‘control’ conditions for two indirect measures of rubber hand effects across two pre-registered studies (n = 140 and n = 45): proprioceptive drift (a change in perceived hand location) and skin conductance response (SCR; a measure of physiological arousal). Participants expectancies for the synchronous condition measures were greater than for asynchronous ‘control’ condition in both studies. Previous work has shown that subjects can voluntarily produce alterations in both subjective experience of body location and in SCR. Thus, indirect measures of rubber hand effects may reflect compliance, bias and phenomenological control in response to demand characteristics, just as for subjective measures, and the asynchronous control condition is in general invalid for controlling demand characteristics in rubber hand procedures. Valid control measures are required to support claims of a role of multi-sensory integration for both direct and indirect measures of rubber hand effects.

scholarly journals Hypothesis awareness confounds asynchronous control conditions in indirect measures of the rubber hand illusion

2021 ◽  
Vol 8 (11) ◽  
Author(s):  
P. Lush ◽  
A. K. Seth ◽  
Z. Dienes
Keyword(s):  
Multisensory Integration ◽  
Visual Stimulation ◽  
Control Measures ◽  
Rubber Hand ◽  
Subjective Report ◽  
Demand Characteristics ◽  
Asynchronous Control ◽  
Indirect Measures ◽  
Body Location ◽  
And Control

Reports of changes in experiences of body location and ownership following synchronous tactile and visual stimulation of fake and real hands (rubber hand (RH) effects) are widely attributed to multisensory integration mechanisms. However, existing control methods for subjective report measures (asynchronous stroking and control statements) are confounded by participant hypothesis awareness; the report may reflect response to demand characteristics. Subjective report is often accompanied by indirect (also called ‘objective’ or ‘implicit’) measures. Here, we report tests of expectancies for synchronous ‘illusion’ and asynchronous ‘control’ conditions across two pre-registered studies ( n = 140 and n = 45) for two indirect measures: proprioceptive drift (a change in perceived hand location) and skin conductance response (a measure of physiological arousal). Expectancies for synchronous condition measures were greater than for asynchronous conditions in both studies. Differences between synchronous and asynchronous control condition measures are therefore confounded by hypothesis awareness. This means indirect measures of RH effects may reflect compliance, bias and phenomenological control in response to demand characteristics, just as for subjective measures. Valid control measures are required to support claims of a role of multisensory integration for both direct and indirect measures of RH effects.

scholarly journals What do participants expect to experience in the rubber hand illusion?

2021 ◽  
Author(s):  
Arran T Reader
Keyword(s):  
Subjective Experience ◽  
The Body ◽  
Rubber Hand Illusion ◽  
Body Ownership ◽  
Rubber Hand ◽  
Demand Characteristics ◽  
Open Questions ◽  
Synchronous Condition ◽  
Subjective Reports

The sense of body ownership (the feeling that the body belongs to the self) is commonly believed to arise through multisensory integration. This is famously shown in the rubber hand illusion (RHI), where touches applied synchronously to a false hand and to the participant’s real hand (which is hidden from view) can induce a sensation of ownership over the fake one. Asynchronous touches weaken the illusion, and are typically used as a control condition. Subjective experience during the illusion is measured using a questionnaire, with some statements designed to capture illusory sensation and others designed as controls. However, recent work by Lush (2020, Collabra: Psychology) claimed that participants may have different levels of expectation for questionnaire items in the synchronous condition compared to the asynchronous condition, and for the illusion-related items compared to the control items. This may mean that the classic RHI questionnaire is poorly controlled for demand characteristics. As such, Lush (2020) suggested that subjective reports in the RHI may reflect compliance or even the generation of experience to meet expectations (‘phenomenological control’), rather than multisensory processes underlying the sense of body ownership. In the current work a conceptual replication of Lush (2020) was performed with an improved experimental design. Participants were presented with a video of the RHI procedure and reported the sensations they would expect to experience, both in open questions and by rating questionnaire items. In keeping with Lush (2020), participants had greater expectations for illusion statements in the synchronous condition compared to the asynchronous condition, and for illusion statements compared to control statements. However, there was also evidence that some expectations may be driven by exposure to the questionnaire items rather than exposure to the illusion procedure. The role of pre-illusion expectations and expectations driven by questionnaire exposure in the RHI require further examination.

scholarly journals Demand characteristics confound the rubber hand illusion

2020 ◽  
Author(s):  
Peter Lush
Keyword(s):  
Rubber Hand Illusion ◽  
Control Methods ◽  
Rubber Hand ◽  
Demand Characteristics ◽  
Psychological Science ◽  
Fit For Purpose ◽  
Procedure Text ◽  
And Control ◽  
Video Demonstration ◽  
Crucial Assumption

Reports of experiences of ownership over a fake hand following simple multisensory stimulation (the ‘rubber hand illusion’) have generated an expansive literature. Because such reports might reflect suggestion effects, demand characteristics are routinely controlled for by contrasting agreement ratings for ‘illusion’ and ‘control’ conditions. However, these methods have never been validated, and recent evidence that response to imaginative suggestion (‘phenomenological control’) predicts illusion report prompts reconsideration of their efficacy. A crucial assumption of the standard approach is that demand characteristics are matched across conditions. Here, a quasi-experiment design was employed to test demand characteristics in rubber hand illusion reports. Participants were provided with information about the rubber hand illusion procedure (text description and video demonstration) and recorded expectancies for standard ‘illusion’ and ‘control’ statements. Expectancies for control and illusion statements in synchronous and asynchronous conditions were found to differ similarly to published illusion reports. Therefore, rubber hand illusion control methods which have been in use for 22 years are not fit for purpose. Because demand characteristics have not been controlled in illusion report in existing studies, the illusion may be, partially or entirely, a suggestion effect. Methods to develop robust controls are proposed. That confounding demand characteristics have been overlooked for decades may be attributable to a lack of awareness that demand characteristics can drive experience in psychological science.

scholarly journals Proprioceptive drift is affected by the intermanual distance rather than the distance from the body’s midline in the rubber hand illusion

2020 ◽  
Vol 82 (8) ◽  
pp. 4084-4095
Author(s):  
Roberto Erro ◽  
Angela Marotta ◽  
Mirta Fiorio
Keyword(s):  
Sensory Information ◽  
Peripersonal Space ◽  
Rubber Hand Illusion ◽  
Minor Role ◽  
Rubber Hand ◽  
Subjective Report ◽  
A Minor ◽  
Proprioceptive Drift ◽  
Subsequent Integration

Abstract In the rubber hand illusion (RHI), simultaneous brush stroking of a subject’s hidden hand and a visible rubber hand induces a transient illusion of the latter to “feel like it’s my hand” and a proprioceptive drift of the hidden own hand toward the rubber hand. Recent accounts of the RHI have suggested that the illusion would only occur if weighting of conflicting sensory information and their subsequent integration results in a statistically plausible compromise. In three different experiments, we investigated the role of distance between the two hands as well as their proximity to the body’s midline in influencing the occurrence of the illusion. Overall, the results suggest that the illusion is abolished when placing the two hands apart, therefore increasing the mismatch between the visual and proprioceptive modality, whereas the proximity of the two hands to the body’s midline plays only a minor role on the subjective report of the illusion. This might be driven by the response properties of visuotactile bimodal cells encoding the peripersonal space around the hand.

The Rubber Hand Illusion in Healthy Younger and Older Adults

2018 ◽  
Vol 31 (6) ◽  
pp. 537-555 ◽  
Author(s):  
Jennifer L. Campos ◽  
Graziella El-Khechen Richandi ◽  
Babak Taati ◽  
Behrang Keshavarz
Keyword(s):  
Skin Temperature ◽  
Subjective Experience ◽  
Age Groups ◽  
Objective Measure ◽  
The Body ◽  
Rubber Hand Illusion ◽  
Body Ownership ◽  
Rubber Hand ◽  
Age Related ◽  
Body Change

Percepts about our body’s position in space and about body ownership are informed by multisensory feedback from visual, proprioceptive, and tactile inputs. The Rubber Hand Illusion (RHI) is a multisensory illusion that is induced when an observer sees a rubber hand being stroked while they feel their own, spatially displaced, and obstructed hand being stroked. When temporally synchronous, the visual–tactile interactions can create the illusion that the rubber hand belongs to the observer and that the observer’s real hand is shifted in position towards the rubber hand. Importantly, little is understood about whether these multisensory perceptions of the body change with older age. Thus, in this study we implemented a classic RHI protocol (synchronous versus asynchronous stroking) with healthy younger (18–35) and older (65+) adults and measured the magnitude of proprioceptive drift and the subjective experience of body ownership. As an adjunctive objective measure, skin temperature was recorded to evaluate whether decreases in skin temperature were associated with illusory percepts, as has been shown previously. The RHI was observed for both age groups with respect to increased drift and higher ratings of ownership following synchronous compared to asynchronous stroking. Importantly, no effects of age and no interactions between age and condition were observed for either of these outcome measures. No effects were observed for skin temperature. Overall, these results contribute to an emerging field of research investigating the conditions under which age-related differences in multisensory integration are observed by providing insights into the role of visual, proprioceptive, and tactile inputs on bodily percepts.

scholarly journals Exploring the subjective experience of the “rubber hand” illusion

2013 ◽  
Vol 7 ◽  
Author(s):  
Camila Valenzuela Moguillansky ◽  
J. Kevin O'Regan ◽  
Claire Petitmengin
Keyword(s):  
Subjective Experience ◽  
Rubber Hand Illusion ◽  
Rubber Hand

Illusions With Hands, but Not With Balloons – Comparing Ownership and Referral of Touch for a Corporal and Noncorporal Object After Visuotactile Stimulation

Perception ◽  
2019 ◽  
Vol 48 (5) ◽  
pp. 447-455 ◽  
Author(s):  
Andreas Kalckert ◽  
Ian Bico ◽  
Jia Xi Fong
Keyword(s):  
Subjective Experience ◽  
Body Part ◽  
Rubber Hand Illusion ◽  
Questionnaire Data ◽  
Rubber Hand ◽  
Perceptual Illusion ◽  
Fine Grained ◽  
Human Body Part ◽  
Significant Difference ◽  
Successful Induction

The rubber hand illusion is a perceptual illusion of perceiving an object like a model hand as part of the own body. The question whether the illusion can be induced with noncorporal objects that do not look like a human body part is not perfectly resolved yet. In this study, we directly assessed the subjective experience of two different components within the illusion (i.e., ownership and referral of touch) when a model hand and a balloon are stimulated. We observed significantly stronger illusion ratings for the hand as compared with the balloon, and only the hand ratings showed a clear affirmation of the illusion. We further conclude that (a) a significant difference between synchronous and asynchronous conditions may not be sufficient to argue for the successful induction of the illusion and (b) the subcomponents show a different pattern in the different conditions, which may lead to alternative interpretations. These observations call for a more fine-grained interpretation of questionnaire data in rubber hand illusion studies.

scholarly journals Order effects in the rubber hand illusion

2021 ◽  
Author(s):  
Peter Lush
Keyword(s):  
Multisensory Integration ◽  
Rubber Hand Illusion ◽  
Order Effects ◽  
Rubber Hand ◽  
Demand Characteristics ◽  
Test Order ◽  
Integration Mechanisms ◽  
Synchronous Condition ◽  
The Difference ◽  
Proprioceptive Drift

Seeing a fake hand brushed in synchrony with brushstrokes to a participant’s hand (the rubber hand illusion; RHI) prompts reports of referred touch, illusory ownership and that the real hand has drifted toward the fake hand (proprioceptive drift). According to one theory, RHI effects are attributable to multisensory integration mechanisms, but they may alternatively (or additionally) reflect the generation of experience to meet expectancies arising from demand characteristics (phenomenological control). Multisensory integration accounts are supported by contrasting synchronous and asynchronous brush stroking conditions, typically presented in counter-balanced order. This contrast is known to be confounded by demand characteristics, but to date there has been no exploration of the role of demand characteristics relating to condition-order. In an exploratory study, existing data from a rubber hand study (n = 124) were analysed to test order effects. Synchronous condition illusion report and the difference between synchronous and asynchronous conditions in both report and proprioceptive drift were greater when the asynchronous condition was performed first (and therefore participants were exposed to the questionnaire materials). These order effects have implications for interpretation of reports of ownership experience: in particular, there was no mean ownership agreement in the synchronous-first group. These data support the theory that reports of ownership of a rubber hand are at least partially attributable to phenomenological control in response to demand characteristics.

scholarly journals Demand Characteristics Confound the Rubber Hand Illusion

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Peter Lush
Keyword(s):  
Rubber Hand Illusion ◽  
Control Methods ◽  
Rubber Hand ◽  
Demand Characteristics ◽  
Psychological Science ◽  
Fit For Purpose ◽  
Procedure Text ◽  
And Control ◽  
Video Demonstration ◽  
Crucial Assumption

Reports of experiences of ownership over a fake hand following simple multisensory stimulation (the ‘rubber hand illusion’) have generated an expansive literature. Because such reports might reflect suggestion effects, demand characteristics are routinely controlled for by contrasting agreement ratings for ‘illusion’ and ‘control’ conditions. However, these methods have never been validated, and recent evidence that response to imaginative suggestion (‘phenomenological control’) predicts illusion report prompts reconsideration of their efficacy. A crucial assumption of the standard approach is that demand characteristics are matched across conditions. Here, a quasi-experiment design was employed to test demand characteristics in rubber hand illusion reports. Participants were provided with information about the rubber hand illusion procedure (text description and video demonstration) and recorded expectancies for standard ‘illusion’ and ‘control’ statements. Expectancies for ‘control’ and ‘illusion’ statements in synchronous and asynchronous conditions were found to differ similarly to published illusion reports. Therefore, rubber hand illusion control methods which have been in use for 22 years are not fit for purpose. Because demand characteristics have not been controlled in illusion report in existing studies, the illusion may be, partially or entirely, a suggestion effect. Methods to develop robust controls are proposed. That confounding demand characteristics have been overlooked for decades may be attributable to a lack of awareness that demand characteristics can drive experience in psychological science.

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