The goal of the present study was to investigate how active visual self-touch modulates ownership illusions during the rubber hand illusion (RHI). 23 healthy test subjects participated. A 2x2x2 repeated measures ANOVA was performed, in which self-touch vs. external touch during RHI induction was examined. Additionally, the effect of touching the rubber hand during the RHI vs not touching it was measured, as well as the location of the rubber hand within or outside of peripersonal space (PPS). The measures used were the behavioral measure of the proprioceptive drift (PD) and a 10-item subjective embodiment questionnaire, including the components “ownerhip”, “location” and “agency”.
Based on previous studies and theories regarding self-touch, it was hypothesized that self-touch would positively modulate body ownership. A further postulation was that touching the rubber hand during the RHI, instead of just performing the stroking motion without the touch, would induce a higher sense of embodiment, which could be confirmed. Lastly, it was hypothesized that embodiment would be positively modulated by the rubber hand being inside the PPS of the subject’s own hand.
Table of Contents
1 Introduction
2 Theoretical background
2.1 Body ownership
2.2 The Rubber Hand Illusion
2.2.1 Psychometrics of body ownership
2.2.2 The neuropsychological mechanisms of the RHI
2.3 Self-touch
2.3.1 Self-Touch and body representations
2.3.2 Self-touch and body-ownership illusions
2.3.3 State of the art
2.3.4 Does active visual self-touch induce a greater ownership illusion than external touch?
2.4 Conceptual Hypotheses
3 Method
3.1 Experimental Design and operationalization of the independent variables
3.2 Measures of illusory ownership
3.2.1 RHI Questionnaire
3.2.2 Proprioceptive drift
3.3 Experimental setup
3.4 Participants
3.4.1 COVID-19
3.5 Procedure
3.5.1 Preparation
3.5.2 Illusion induction
3.6 Empirical hypotheses
4 Results
4.1 Data preparation
4.2 Descriptive statistics
4.3 Hypothesis testing
4.3.1 Testing of hypothesis 1
4.3.2 Testing of hypothesis 2
4.3.3 Testing of hypothesis 3
4.3.4 Explorative analysis
5 Discussion
5.1 Summary and discussion of results
5.2 Limitations
5.3 Future research and implications
5.4 Conclusion
Research Objectives and Topics
The primary objective of this study is to investigate how active visual self-touch influences ownership illusions during the Rubber Hand Illusion (RHI). It specifically seeks to determine whether self-touch modulates body ownership more effectively than external touch, and to what extent the location of the rubber hand relative to peripersonal space (PPS) and the presence of tactile stimulation influence the strength of the illusion.
- The impact of active visual self-touch on body ownership.
- The influence of peripersonal space (PPS) on illusion strength.
- The role of tactile stimulation versus non-tactile visual cues in embodiment.
- The dissociation between implicit (proprioceptive drift) and explicit (subjective questionnaire) measures of ownership.
- Interaction effects between touch source, touch type, and spatial location.
Excerpt from the Book
1 Introduction
When touching or looking at our own body parts, we instantly have the feeling that they belong to us. We have the ability to perceive our own body as distinct from other entities and objects in the environment. Typically, we also have the feeling of being in control of our own bodily actions. These experiences are all essential parts of self-consciousness (Ehrsson, Holmes & Passingham, 2005) and fall under the term of “body ownership” (Gallagher, 2000).
While for most of the population, the feeling of body ownership seems to be only natural, this is not the case for everyone. A number of neurological disorders are characterized by a dysfunction in bodily experience, which may include feelings of disembodiment towards body parts, “filling in” of amputated limbs, or even a reduplication of certain body parts (Giummarra, Gibson, Georgiou-Karistianis & Bradshaw, 2008). An example is the case of body integrity dysphoria, a condition in which patients feel a strong sense of alienation from one or several body parts, which is often accompanied by a strong desire for amputation (Brugger & Lenggenhager, 2014). The “counterpart” of this clinical group would be that of amputees, who may suffer from phantom limb pain, or feelings of disownership towards their prosthesis (Bekrater-Bodmann, 2020).
Body ownership is assumed to be formed both through top-down and bottom-up experiences: it relies on sensory input from the environment (Tsakiris, Hesse, Boy, Haggard & Fink, 2007), but also on the coherence of that sensory input with mental representation of our bodily structure (Blanke, 2012). Despite the crucial role these bodily representations and experiences of body ownership have for our sense of self, neuropsychology and experimental psychology have proven that mental representation and conscious awareness of our own body are not cognitively impenetrable but can be manipulated (Botvinick & Cohen, 1998). Several experimental manipulations of body ownership -like the Rubber Hand Illusion- have shown that the formation of bodily self-representation occurs through the integration and correspondence of multisensory signals (Hara, Rognini, Higuchi & Pozeg, 2015).
Summary of Chapters
1 Introduction: Provides an overview of body ownership and its clinical relevance, introducing the Rubber Hand Illusion as a paradigm for studying bodily self-representation and self-touch.
2 Theoretical background: Reviews the concept of body ownership, the Rubber Hand Illusion, the role of peripersonal space, and existing literature on self-touch.
3 Method: Outlines the 2x2x2 experimental design, describing the measures for illusory ownership (questionnaire and proprioceptive drift) and the procedure used for 23 participants.
4 Results: Presents the statistical findings from the repeated measures ANOVA, including main effects and interactions of self-touch, touch type, and rubber hand location on embodiment scores and proprioceptive drift.
5 Discussion: Interprets the findings regarding self-touch and PPS, discusses methodological limitations such as the mirror and paintbrush use, and proposes directions for future research in bodily self-consciousness.
Keywords
body ownership, embodiment, rubber hand illusion, peripersonal space, proprioceptive drift, body plasticity, self-touch, multisensory integration, body schema, subjective ownership, agency, efferent signals, motor control, bodily self-consciousness, mirror paradigm
Frequently Asked Questions
What is the fundamental focus of this research?
The work investigates the role of active visual self-touch in modulating the Rubber Hand Illusion (RHI) and how various factors like tactile input and peripersonal space interact to shape body ownership.
What are the central thematic fields?
The core themes include body ownership, bodily self-consciousness, multisensory integration, the influence of peripersonal space (PPS), and the comparison between active self-generated touch and externally administered touch.
What is the primary objective of the thesis?
The primary aim is to determine if active visual self-touch induces a stronger ownership illusion than external touch and to analyze the role of spatial proximity and physical contact in this process.
Which scientific method is applied?
The study employs a 2x2x2 within-subject experimental design, utilizing a repeated measures ANOVA to analyze both implicit (proprioceptive drift) and explicit (subjective questionnaire) measures of embodiment.
What topics are discussed in the main body?
The main sections cover the theoretical foundation of body ownership and self-touch, the detailed experimental methodology, the analysis of behavioral and questionnaire data, and a discussion of the observed results and their implications.
Which keywords define the work?
The work is defined by concepts such as body ownership, embodiment, rubber hand illusion, proprioceptive drift, multisensory integration, and the specific role of peripersonal space in self-representation.
Why did the study observe stronger illusions outside of the hypothesized PPS?
The unexpected result suggests a possible dynamic modulation of PPS representations or that the mirror setup used for the illusion might have affected the participants' ability to judge distance and space.
How did the use of a metronome affect the results?
The metronome standardized the stroking rhythm to ensure consistency across conditions, but the author notes that it may have reduced the "voluntary" aspect of active self-touch, which could be a factor in the lack of significant differences found between touch sources.
- Citar trabajo
- Pauline Kopka (Autor), 2021, The Role of Visual Active Self-Touch in Body Ownership, Múnich, GRIN Verlag, https://www.grin.com/document/1195193
