> Disorders > Mental or Behavioral Dysfunction > Illusions

Illusions

Illusions are perceptual experiences that differ from objective reality.
They can involve visual, auditory, tactile, or other sensory modalities, and can be induced through various techniques.
Illusions provide insights into the brain's mechanisms for interpreting and processing sensory information, and are a valuable tool for understanding human perception and cognition.
This MeSH term covers the study of different types of illusions, their underlying neural and psychological processes, and their applications in research and entertianment.
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Most cited protocols related to «Illusions»

Lightweight 2D Protein Visualization

Cited 86 times

For visualization, we developed a matplotlib^{32 (link)} compatible module for displaying the 3D ribbon diagram of a protein structure or complex. The ribbon can be colored by residue index (N to C terminus) or by a predicted confidence metric (such as pLDDT). For complexes, each protein can be colored by chain ID. Instead of using a 3D renderer, we instead use a 2D line plotting based technique. The lines that make up the ribbon are plotted in the order in which they appear along the z-axis. Furthermore, we add shade to the lines according to the z-axis. This creates the illusion of a 3D rendered graphic. The advantage over a 3D renderer is that the images are very lightweight, can be used in animations and saved as vector graphics for lossless inclusion in documents. Given that the 2D renderer is not interactive, we additionally included a 3D visualization option using py3Dmol^{33 (link)} in the ColabFold notebooks.

Mirdita M., Schütze K., Moriwaki Y., Heo L., Ovchinnikov S, & Steinegger M. (2022). ColabFold: making protein folding accessible to all. Nature Methods, 19(6), 679-682.

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Publication 2022

Cloning Vectors Epistropheus Illusions Proteins Staphylococcal Protein A

Measuring Ownership and Agency in Rubber Hand Illusion

Cited 19 times

In Experiments 1 and 3, we used a 16-statement questionnaire (Table 1). Four statements referred to the feeling of ownership (e.g., “I felt as if I was looking at my own hand”), and four statements described sensations related to agency (e.g., “I felt as if was causing the movement I saw”). These statements were adopted from existing questionnaires used in traditional rubber hand illusion experiments (e.g., Botvinick and Cohen, 1998 (link); Longo et al., 2008 (link)). The remaining eight statements were control statements, with four for ownership and four for agency (e.g., “I felt as if I had more than one right hand” and “It seemed as if the rubber hand had a will of its own”). These served as controls for task compliancy, suggestibility, and expectancy effects. The control statements were created based on similar control statements used in earlier studies of the rubber hand illusion (e.g., Botvinick and Cohen, 1998 (link); Petkova and Ehrsson, 2008 (link)) in that they include statements that bear several similarities to the illusion-specific statements (e.g., includes the word “will” or “hand”) but do not capture the phenomenological experiences of ownership or agency. Participants were exposed to 3 min of stimulation for each individual condition, after which they reported their subjective experience on a 7-point Likert scale ranging from “−3” (totally disagree) to “+3” (totally agree), with “0” indicating neither agreement nor disagreement (“uncertain”). In Experiments 2 and 4, we applied a shorter version of the questionnaire to confirm the subjective experience of ownership and agency in these groups of participants. Here, we only included the most important statements related to the perceptions of ownership and agency, i.e., those that had displayed clear and reliable differences in the previous experiments, with the aim of examining possible correlations between the illusion categories and proprioceptive drift (see Table 1).
To analyze the questionnaire data, the average of the scores for the four statements related to ownership was computed to obtain a single “ownership statement” score. Similarly, the “agency statement” score was defined as the mean score of the four statements related to the sense of agency. The four control statements for ownership and agency were also averaged to obtain “ownership control statement” and “agency control statement” scores, respectively. Thus, references in the text to “ownership statements” or “agency statements” always refer to the average scores of the four individual statements in the original questionnaires unless explicitly stated otherwise. The ownership and agency statement scores were compared with their corresponding control statements. An average rating ≥ +1 indicates that on the group level, the participants affirmed the statement, i.e., they had experienced ownership or agency (this criterion has been used before; see Ehrsson et al., 2004 (link); Petkova and Ehrsson, 2009 (link)).

Kalckert A, & Ehrsson H.H. (2012). Moving a Rubber Hand that Feels Like Your Own: A Dissociation of Ownership and Agency. Frontiers in Human Neuroscience, 6, 40.

Publication 2012

Bears Feelings Illusions Movement Proprioception Rubber Volition

Validity and Utility of Multiple Imputation

Cited 15 times

As with any statistical technique, the validity of MI depends on the validity of its assumptions. But when those assumptions are met, MI rests on well-established theory.^{3 ,5} Moreover, substantial empirical support exists for the validity of MI in simulations, including those based on real data patterns.^{9 (link)} In principle, computational speed can be a problem because each analysis must be run multiple times, but in practice, this is rarely an issue with modern computers.
Many nonstatisticians chafe at ‘making up data’ as is done in MI and note that the validity of MI depends on an assumption about which factors relate to the probability that a data point is missing. Because of concern this assumption may be violated, it is tempting to retreat to the safe haven of complete case analysis, ie, only analyze the participants without missing values. This safe haven is, however, illusory. Although rarely made explicit by users, complete case analysis requires a far more restrictive assumption than whether any data-point is missing at random. Other common strategies - mean imputation, last observation carried forward, and other single imputation approaches - underestimate standard errors by ignoring or underestimating the inherent uncertainty created by missing data, a problem MI helps overcome.

Li P., Stuart E.A, & Allison D.B. (2015). Multiple Imputation: A Flexible Tool for Handling Missing Data. JAMA, 314(18), 1966-1967.

Publication 2015

Illusions REST protein, human

Quantifying Perceptual Experiences in Rubber Hand Illusion

Cited 8 times

To quantify the perceptual experiences associated with the illusion, we used questionnaires with visual analogue rating scales which were presented at the end of each condition. The questionnaires were adapted from a previous study investigating perceptual experiences during the traditional rubber hand illusion [22] (link). In the questionnaire, the participants were asked to affirm or deny ten possible perceptual effects using a ten-point visual analogue scale ranging from 0 to 9. The participants were informed that 0 meant “I do not agree at all” and 9, “I agree completely”. Two statements were used to capture the key perceptual components of the illusion of owning the rubber hand (S1–S2); two statements were created to describe the possible experience of disowning the real (right) hand (S3–S4); and two statements where formulated to capture the illusion of owning two right hands (S5–S6). The last four statements served as controls for suggestibility and task-compliance (S7–S10). For each participant we clarified that the formulation “both hands” means “the rubber limb and your real right hand” to ensure that they understood which two limbs we were referring to in our statements.

Guterstam A., Petkova V.I, & Ehrsson H.H. (2011). The Illusion of Owning a Third Arm. PLoS ONE, 6(2), e17208.

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Publication 2011

Illusions Rubber Visual Analog Pain Scale

Adaptive Psychophysical Assessment of Illusory Contours

Cited 7 times

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Publication 2014

Accidents Acclimatization Auditory Perception Entropy Illusions Primed In Situ Labeling Psychometrics Training Programs

Most recents protocols related to «Illusions»

Evaluating Sense of Presence and Cybersickness in Virtual Environments

The four presence dimensions were assessed with a 16-item questionnaire in French (Table 2, Wagener and Simon, in preparation) that is consistent with Slater’s (2009 (link)) and Biocca and colleagues’ (2003) theoretical conceptions. Participants replied on a 7-point scale ranging from 1 = “totally disagree” to 7 = “totally agree”. The four dimensions included “place illusion” (i.e., the sense of being in the place); “plausibility illusion” (i.e., the feeling that the scenario is actually taking place); “copresence illusion” (i.e., the sense of sharing the environment with other characters); and “social presence illusion” (i.e., the feeling that a psychological link exists between oneself and the other characters). Scores of each dimension range from 4 to 28 with higher scores indicating higher sense of presence. The psychometric qualities of this questionnaire are satisfactory (confirmatory factorial analysis: χ²/dl = 167.63/98 = 1.71; RMSEA = 0.067; SRMR = 0.06; CFI = 0.996; TLI = 0.995, McDonald’s omega: ω^place = 0.89, ω^plausibility = 0.88, ω^copresence = 0.80, ω^social = 0.81).Table 2

Items measuring the four dimensions of presence in English and French

Place illusion

I felt like I was “there”, in the immersive environment

J'avais l'impression d'être « là», dans l'environnement immersif

I felt I was present in the environment

J’ai eu l’impression d’être présent(e) dans l'environnement

I felt enfulged by the virtual environment

Je me suis senti(e) enveloppé(e) par l’environnement virtuel

I felt like I was in the same place as the characters and/or objects

J’avais l’impression d’être dans le même lieu que les personnages et/ou objets

Plausibility illusion

The virtual environment seemed real

L’environnement virtuel me semblait réel

It was as if the elements had really happened

Pour moi, c'est comme si les éléments s'étaient réellement produits

The events I experienced seemed real

Les événements vécus me semblaient réels

The world I interacted with felt real

Le monde avec lequel j'ai interagi me semblait réel

Co-presence illusion

I felt like I was interacting with other humans

J'ai eu le sentiment d'interagir avec d'autres êtres humains

I felt the presence of other people in the environment

J'ai ressenti la présence d'autres personnes dans l'environnement

I felt that characters were aware of my presence

J’ai eu l’impression que les personnages étaient conscients de ma présence

I felt that characters could respond to my actions

J’ai eu l’impression que des personnages pouvaient répondre à mes actions

Social presence illusion

I felt psychologically connected to other individuals

Je me suis senti psychologiquement connecté aux autres individus

I describe the social interactions I experienced as intimate and personal

Je peux qualifier les interactions sociales vécues d'intimes et personnelles

I felt part of/excluded from a group

J'avais le sentiment de faire partie / d'être exclu d'un groupe

I felt a positive or negative connection with the characters

J'ai senti un lien positif ou négatif avec les personnages

Cybersickness was assessed with the French version (Bouchard et al. 2011 ) of the Simulator Sickness Questionnaire (SSQ; Kennedy et al. 1993 (link)). The SSQ consists of 16 items distributed across two subscales that assess nausea (SSQ^N) and oculomotor symptoms (SSQ^OM). Participants reply on 4-point Likert scale ranging from 0 = “not at all” to 3 = “severely” regarding the extent to which the symptom is present. Scores range from 0 to 24 for each subscale with higher scores indicating higher levels of cybersickness.

Della Libera C., Simon J., Larøi F., Quertemont E, & Wagener A. (2023). Using 360-degree immersive videos to assess multiple transdiagnostic symptoms: A study focusing on fear of negative evaluation, paranoid thoughts, negative automatic thoughts, and craving. Virtual Reality.

Publication 2023

Character Conception Feelings Illusions Nausea Psychometrics Spleen Submersion

Visual Cliff Acuity Assessment in Mice

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Publication 2023

Illusions Light MAZE protocol Mice, House Open Field Test Vision Tests Visual Acuity

Investigating the Role of Eye and Hand Movements in the Rubber Hand Illusion

All data met the normality assumption (p>.057 in all cases), therefore, parametric tests were used throughout (see Data S1). Analysis for the CCT followed Zopf et al.²⁴ (link) Trials in which participants responded too soon (≤150 ms) or too late (≥1500 ms) were discarded from the analyses and only the reaction times (RT) for correct responses were used.²⁴ (link) The CCT effect was calculated as participants’ performance on non-homologous minus homologous trials.²⁴ (link) As accuracy and RT in the CCT are interdependent,²⁴ (link)^,⁵⁷ results from each participant were integrated into an Inverse Effectiveness Score (CCT-IES; reported in Figure 1C in the main text).²⁴ (link)^,⁵⁷ ^,⁵⁸ Supplemental analyses of participants’ reaction times (CCT-RT) and percentage errors (CCT-PE) showed substantially similar results than the combined CCT-IES measure (see Figure S2). A 2 (effector-type: hand, eye) x 2 (spatial-congruency: congruent, incongruent) repeated measures ANOVA was used to analyse CCT data.
The Onset Time of the RHI was analysed with a similar 2 × 2 rmANOVA. Yet, given that not all participants reported an illusion in all four experimental conditions, statistical analyses were only run on the data from participants who responded in all the blocks (n = 12; Figure 1D). The rationale for this choice is that missing values may potentially be due to a range of reasons, from not experiencing any RHI to forgetting the instructions. For example, during the debriefing at the end of the experiment a few participants even reported they had forgotten to step on the pedal because they were experiencing a strong RHI (see Figure S3 for details on formal analyses supporting this rationale).
Finally, given that Subjective Reports were given on a continuous visual analog scale (from −100 = strongly disagree to +100 = strongly agree) instead of a 7-points Likert scale,²² (link) participants’ responses were also analysed through parametric tests. Participants’ agreement with each statement of the questionnaire were first averaged across question type (i.e., RHI/control items), and then analysed in a 2 (spatial-congruency: congruent, incongruent) x 2 (effector-type: hand, eye) x 2 (item-type: illusion, control) rmANOVA.
For each of the three dependent variables, we expected a main effect of spatial-congruency, in line with the general principle that crossmodal stimulation must be spatially congruent in order to elicit the RHI.³⁷ (link) Crucially, in line with our main hypothesis of similar RHI for hand and eye movements, we also predicted no significant interaction between main effects. Given that the experiment was designed to allow asserting the null hypothesis (i.e., eye movements and hand movements induce the same amount of RHI), non-significant interactions between spatial-congruency and effector-type were further tested through Bayesian t-tests on the difference between spatially congruent/incongruent conditions in each type of movement. This allowed us to determine whether the datasupported the null hypothesis or if, alternatively, the null result could reflect insufficient statistical power.²⁶ (link) All the ANOVAs were conducted using IBM SPSS Statistics for Windows, version 23 (IBM Corp.,USA). Bayesian analyses were run on JASP v. 0.12.1 (JASP Team 2016, University of Amsterdam).

Cataldo A., Di Luca M., Deroy O, & Hayward V. (2023). Touching with the eyes: Oculomotor self-touch induces illusory body ownership. iScience, 26(3), 106180.

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Publication 2023

Eye Movements Foot Illusions Movement neuro-oncological ventral antigen 2, human Visual Analog Pain Scale

Comparing Visual and Tactile Rubber Hand Illusion

To compare the efficacy of hand and eye movements in inducing the RHI, we employed a 2 (effector-type: hand, eye) x 2 (spatial-congruency: congruent, incongruent) within-subject design. The effector-type factor was blocked and counterbalanced across participants, whilethe order of the spatial-congruency conditions was randomised within participant. To assess the strength of the RHI, we selected three of the best-established measures for RHI²⁵ (link) that are thought to underly different aspects of the illusion.⁴⁷ (link) First, the Crossmodal Congruency Task (CCT) is considered one of the most objective behavioural measures of the crossmodal integration responsible for the RHI.²⁴ (link)^,⁵⁶ (link) The task measures the interference of visual stimuli presented on the rubber hand on participants’ performance in a tactile discrimination task. Second, the Onset Time (OT) of the RHI has been indicated as a good predictor of the strength of the RHI.²³ (link) Finally, Subjective Reports (SR) of RHI are commonly considered a valid measure of participants’ phenomenology.²² (link) Proprioceptive drift, another classical measure of RHI,²⁵ (link)^,⁴⁷ (link) was difficult to implement, as our eye-tracking montage would have interfered with the pointing procedure. Other measures of RHI, such as galvanic skin conductance response to a threating stimulus and skin temperature were also discarded as they were difficult to integrate within our setup/procedure.

Cataldo A., Di Luca M., Deroy O, & Hayward V. (2023). Touching with the eyes: Oculomotor self-touch induces illusory body ownership. iScience, 26(3), 106180.

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Publication 2023

Discrimination, Psychology Eye Movements Galvanic Skin Response Illusions Proprioception Rubber Skin Temperature Task Performance

Quantifying Rubber Hand Illusion Experience

We used two similar questionnaires to quantify participants’ phenomenological experience of the RHI induced by either hand or eye movements. The questionnaires were completed at the end of each block. Each questionnaire was composed by eight items directly derived from previous RHI studies.²² (link) The eight items were divided in two categories: three experimental questions, aiming to quantify the strength of the illusion, and five control questions, aiming to assess participants’ suggestionability:

It seemed as if I were feeling the touch of my finger/the red light in the location where I touched/gazed the rubber hand.

It seemed as if the touch I felt was caused by my finger/the red light touching the rubber hand.

I felt as if the rubber hand were my hand.

It felt as if my (real) hand were drifting towards the rubber hand.

It seemed as if I might have more than one left hand.

It seemed as if the touch I was feeling came from somewhere between my own hand and the rubber hand.

It felt as if my (real) hand were turning ‘rubbery’.

It felt as if the rubber hand were drifting towards my (real) hand.

Each statement was projected directly onto the easel in front of the participants, in a randomised order. A Visual Analog Scale (VAS) from “strongly disagree” to “strongly agree” was presented below each statement, and participants used a mouse to adjust a slider according to their agreement with each sentence.

Cataldo A., Di Luca M., Deroy O, & Hayward V. (2023). Touching with the eyes: Oculomotor self-touch induces illusory body ownership. iScience, 26(3), 106180.

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Publication 2023

Eye Movements Feelings Fingers Illusions Light Mus Rubber Touch Visual Analog Pain Scale

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The OptoMotry is a laboratory equipment designed for visual function assessment. It utilizes an automated virtual-reality system to measure various aspects of visual perception in laboratory animals.

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Presentation software is a computer program designed to create and display visual presentations. It allows users to organize and present information, such as text, images, and multimedia, in a structured format. The core function of this software is to facilitate the creation and display of digital slides or pages that can be used for various purposes, including business meetings, educational lectures, and public speaking events.

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The HMZ-T1 is a head-mounted display device produced by Sony. It features two OLED panels, one for each eye, providing a virtual large screen experience. The device is designed to connect to various video sources, such as a TV, computer, or gaming console, and display the content directly in front of the user's eyes.

What are the different types of illusions?

Illusions can occur in various sensory modalities, including visual, auditory, tactile, and even olfactory. Some common types of illusions include optical illusions, auditory illusions, haptic (touch) illusions, and cognitive illusions. Each type of illusion involves distinct neural and psychological mechanisms that provide insights into how the brain processes and interprets sensory information.

How can illusions be used in research and entertainment?

Illusions are a valuable tool for understanding human perception and cognition. In research, the study of illusions helps scientists unravel the brain's mechanisms for interpreting sensory data. Illusions can be used to test hypotheses, explore the limits of perception, and develop new technologies. In entertainment, illusions are often used in magic tricks, optical art, and interactive exhibits to create awe-inspiring experiences and challenge our preconceptions about reality.

What are some practical applications of illusions?

Illusions have a wide range of practical applications, from improving user interfaces and enhancing virtual reality experiences to informing the design of medical devices and developing more effective training simulations. For example, certain visual illusions can be used to create the perception of depth in 2D displays, while auditory illusions can be leveraged to create more immersive audio environments. Illusions can also be applied in fields like ergonomics, where they can be used to influence the user's perception of size, weight, or texture.

How can PubCompare.ai assist with Illusions research?

PubCompare.ai allows you to screen protocol literature more efficiently and leverage AI to pinpoint critical insights. The platform can help researchers identify the most effective protocols related to Illusions for their specific research goals. PubCompare.ai's AI-driven analysis can highlight key differences in protocol effectiveness, enabling you to choose the best option for reproducibility and accuracy. This can save time, reduce research costs, and improve the overall quality and reliability of your Illusions-related studies.

What are some common challenges in using Illusions effectively?

One of the key challenges in using Illusions effectively is ensuring reproducibility and accuracy. Illusions can be highly sensitive to contextual factors, such as the viewing conditions, the observer's prior experiences, and the specific techniques used to induce the illusion. This can make it difficult to replicate findings across different studies or settings. Additionally, some illusions may require specialized equipment or expertise to create and observe, which can limit their accessibility. PubCopmare.ai can help address these challenges by providing researchers with the tools and insights needed to identify the most reliable and effective Illusions-related protocols.

More about "Illusions"

Delusions, hallucinations, sensory distortions, perceptual anomalies, and visual/auditory/tactile/olfactory/gustatory illusions are fascinating phenomena that provide insights into the brain's intricate mechanisms for interpreting and processing sensory information.
These perceptual experiences, which differ from objective reality, can be induced through various techniques and are a valuable tool for understanding human perception and cognition.
Researchers utilize a range of technologies, such as MATLAB, OptoMotry, Presentation software, Oculus Rift DK2, SPSS Statistics 20, Ethovision software, Google Cloud Services, MATLAB 8.1, COMSOL Multiphysics 5.5, and HMZ-T1, to study the underlying neural and psychological processes of illusions.
These cutting-edge capabilities enable scientists to explore the secrets behind these fascinating phenomena and unravel the complexities of human perception.
Illusions can involve various sensory modalities, including visual, auditory, tactile, olfactory, and gustatory, and can be categorized into different types, such as optical, auditory, tactile, and cognitive illusions.
Understanding the mechanisms behind these illusory experiences is crucial for advancing fields like neuroscience, psychology, and cognitive science.
By leveraging the insights gained from the study of illusions, researchers can develop new techniques for improving human-computer interaction, enhancing virtual reality experiences, and optimizing sensory processing in various applications.
Additionally, the application of illusions in entertainment and art can provide unique and captivating experiences for audiences.
Explore the cutting-edge capabilities of PubCompare.ai, your AI-powered platform for enhancing reproducibility and research accuracy, to discover the latest protocols, pre-prints, and patents related to the study of illusions.
Experience the power of science-driven insights and take your research to new heights, unlocking the secrets behind these fascinating perceptual phenomena.