Effects of neural oscillation power and phase on discrimination performance in a visual tilt illusion.

Neural oscillations reflect fluctuations in the relative excitation/inhibition of neural systems1,2,3,4,5 and are theorized to play a critical role in canonical neural computations6,7,8,9 and cognitive processes.10,11,12,13,14 These theories have been supported by findings that detection of visual stimuli fluctuates with the phase of oscillations prior to stimulus onset.15,16,17,18,19,20,21,22,23 However, null results have emerged in studies seeking to demonstrate these effects in visual discrimination tasks,24,25,26,27 raising questions about the generalizability of these phenomena to wider neural processes. Recently, we suggested that methodological limitations may mask effects of phase in higher-level sensory processing.28 To test the generality of phasic influences on perception requires a task that involves stimulus discrimination while also depending on early sensory processing. Here, we examined the influence of oscillation phase on the visual tilt illusion, in which a center grating has its perceived orientation biased away from the orientation of a surround grating29 due to lateral inhibitory interactions in early visual processing.30,31,32 We presented center gratings at participants' subjective vertical angle and had participants report whether the grating appeared tilted clockwise or counterclockwise from vertical on each trial while measuring their brain activity with electroencephalography (EEG). In addition to effects of alpha power and aperiodic slope, we observed robust associations between orientation perception and alpha and theta phase, consistent with fluctuating illusion magnitude across the oscillatory cycle. These results confirm that oscillation phase affects the complex processing involved in stimulus discrimination, consistent with its purported role in canonical computations that underpin cognition.

Fluid face but not gender: Enfacement illusion through digital face filters does not affect gender identity.

It has been shown that observing a face being touched or moving in synchrony with our own face increases self-identification with the former which might alter both cognitive and affective processes. The induction of this phenomenon, termed enfacement illusion, has often relied on laboratory tools that are unavailable to a large audience. However, digital face filters applications are nowadays regularly used and might provide an interesting tool to study similar mechanisms in a wider population. Digital filters are able to render our faces in real time while changing important facial features, for example, rendering them more masculine or feminine according to normative standards. Recent literature using full-body illusions has shown that participants' own gender identity shifts when embodying a different gendered avatar. Here we studied whether participants' filtered faces, observed while moving in synchrony with their own face, may induce an enfacement illusion and if so, modulate their gender identity. We collected data from 35 female and 33 male participants who observed a stereotypically gender mismatched version of themselves either moving synchronously or asynchronously with their own face on a screen. Our findings showed a successful induction of the enfacement illusion in the synchronous condition according to a questionnaire addressing the feelings of ownership, agency and perceived similarity. However, we found no evidence of gender identity being modulated, neither in explicit nor in implicit measures of gender identification. We discuss the distinction between full-body and facial processing and the relevance of studying widely accessible devices that may impact the sense of a bodily self and our cognition, emotion and behaviour.

How small changes to one eye's retinal image can transform the perceived shape of a very familiar object.

Vision can provide useful cues about the geometric properties of an object, like its size, distance, pose, and shape. But how the brain merges these properties into a complete sensory representation of a three-dimensional object is poorly understood. To address this gap, we investigated a visual illusion in which humans misperceive the shape of an object due to a small change in one eye's retinal image. We first show that this illusion affects percepts of a highly familiar object under completely natural viewing conditions. Specifically, people perceived their own rectangular mobile phone to have a trapezoidal shape. We then investigate the perceptual underpinnings of this illusion by asking people to report both the perceived shape and pose of controlled stimuli. Our results suggest that the shape illusion results from distorted cues to object pose. In addition to yielding insights into object perception, this work informs our understanding of how the brain combines information from multiple visual cues in natural settings. The shape illusion can occur when people wear everyday prescription spectacles; thus, these findings also provide insight into the cue combination challenges that some spectacle wearers experience on a regular basis.

Research on the cognitive neural mechanism of privacy empowerment illusion cues regarding comprehensibility and interpretability for privacy disclosures.

In the era of artificial intelligence, privacy empowerment illusion has become a crucial means for digital enterprises and platforms to "manipulate" users and create an illusion of control. This topic has also become an urgent and pressing concern for current research. However, the existing studies are limited in terms of their perspectives and methodologies, making it challenging to fully explain why users express concerns about privacy empowerment illusion but repeatedly disclose their personal information. This study combines the associative-propositional evaluation model (APE) and cognitive load theory, using event-related potential (ERP) technology to investigate the underlying mechanisms of how the comprehensibility and interpretability of privacy empowerment illusion cues affect users' immediate attitudes and privacy disclosure behaviours; these mechanisms are mediated by psychological processing and cognitive load differences. Behavioural research results indicate that in the context of privacy empowerment illusion cues with low comprehensibility, users are more inclined to disclose their private information when faced with high interpretability than they are when faced with low interpretability. EEG results show that in the context of privacy empowerment illusion cues with low comprehensibility, high interpretability induces greater P2 amplitudes than does low interpretability; low interpretability induces greater N2 amplitudes than does high interpretability. This study extends the scopes of the APE model and cognitive load theory in the field of privacy research, providing new insights into privacy attitudes. Doing so offers a valuable framework through which digital enterprises can gain a deeper understanding of users' genuine privacy attitudes and immediate reactions under privacy empowerment illusion situations. This understanding can help increase user privacy protection and improve their overall online experience, making it highly relevant and beneficial.

"It doesn't matter if you are in charge of the trees, you always miss the trees for the forest": Power and the illusion of explanatory depth.

Power can increase overconfidence and illusory thinking. We investigated whether power is also related to the illusion of explanatory depth (IOED), people's tendency to think they understand the world in more detail, coherence, and depth than they actually do. Abstract thinking was reported as a reason for the IOED, and according to the social distance theory of power, power increases abstract thinking. We linked these literatures and tested construal style as a mediator. Further, predispositions can moderate effects of power and we considered narcissism as a candidate because narcissism leads to overconfidence and may thus increase the IOED especially in combination with high power. In three preregistered studies (total N = 607), we manipulated power or measured feelings of power. We found evidence for the IOED (regarding explanatory knowledge about devices). Power led to general overconfidence but had only a small impact on the IOED. Power and narcissism had a small interactive effect on the IOED. Meta-analytical techniques suggest that previous findings on the construal-style-IOED link show only weak evidential value. Implications refer to research on management, power, and overconfidence.

Brightness illusions drive a neuronal response in the primary visual cortex under top-down modulation.

Brightness illusions are a powerful tool in studying vision, yet their neural correlates are poorly understood. Based on a human paradigm, we presented illusory drifting gratings to mice. Primary visual cortex (V1) neurons responded to illusory gratings, matching their direction selectivity for real gratings, and they tracked the spatial phase offset between illusory and real gratings. Illusion responses were delayed compared to real gratings, in line with the theory that processing illusions requires feedback from higher visual areas (HVAs). We provide support for this theory by showing a reduced V1 response to illusions, but not real gratings, following HVAs optogenetic inhibition. Finally, we used the pupil response (PR) as an indirect perceptual report and showed that the mouse PR matches the human PR to perceived luminance changes. Our findings resolve debates over whether V1 neurons are involved in processing illusions and highlight the involvement of feedback from HVAs.

Probing corporeal awareness in women through virtual reality induction of embreathment illusion.

We capitalized on the respiratory bodily illusion that we discovered in a previous study and called 'Embreathment' where we showed that breathing modulates corporeal awareness in men. Despite the relevance of the issue, no such studies are available in women. To bridge this gap, we tested whether the synchronization of avatar-participant respiration patterns influenced females' bodily awareness. We collected cardiac and respiratory interoceptive measures, administered body (dis)satisfaction questionnaires, and tracked participants' menstrual cycles via a mobile app. Our approach allowed us to characterize the 'Embreathment' illusion in women, and explore the relationships between menstrual cycle, interoception and body image. We found that breathing was as crucial as visual appearance in eliciting feelings of ownership and held greater significance than any other cue with respect to body agency in both women and men. Moreover, a positive correlation between menstrual cycle days and body image concerns, and a negative correlation between interoceptive sensibility and body dissatisfaction were found, confirming that women's body dissatisfaction arises during the last days of menstrual cycle and is associated with interoception. These findings have potential implications for corporeal awareness alterations in clinical conditions like eating disorders and schizophrenia.

The effect of measurement error on the positive predictive value of PSW methods for SLD identification: How buffer zones dispel the illusion of inaccuracy.

Patterns of Strengths and Weaknesses (PSW) methods are widely used for identifying specific learning disabilities (SLDs). Several researchers, however, have reported that the diagnostic accuracy of PSW methods is unacceptably low when strict thresholds were used to identify students with SLDs. We believe these findings give a misleading impression of the magnitude of the diagnostic errors that are likely to arise in PSW assessments. In a simulation study of 10 million cases using a simplified PSW method for demonstration, most of what have been called diagnostic errors were cases in which observed scores and true scores fell on opposite sides of a strict threshold but were still within a buffer zone the size of a typical measurement error. Because small score differences do not result in meaningfully different case conceptualizations, the use of buffer zones reveals that previous estimates of the diagnostic accuracy of PSW methods are misleadingly low. We also demonstrate that diagnostic decisions become increasingly reliable when observed scores are comfortably distant from diagnostic thresholds. For practitioners, we present a flowchart and practical guidelines to improve the accuracy and stability of SLD identification decisions.

Artificial intelligence and illusions of understanding in scientific research.

Scientists are enthusiastically imagining ways in which artificial intelligence (AI) tools might improve research. Why are AI tools so attractive and what are the risks of implementing them across the research pipeline? Here we develop a taxonomy of scientists' visions for AI, observing that their appeal comes from promises to improve productivity and objectivity by overcoming human shortcomings. But proposed AI solutions can also exploit our cognitive limitations, making us vulnerable to illusions of understanding in which we believe we understand more about the world than we actually do. Such illusions obscure the scientific community's ability to see the formation of scientific monocultures, in which some types of methods, questions and viewpoints come to dominate alternative approaches, making science less innovative and more vulnerable to errors. The proliferation of AI tools in science risks introducing a phase of scientific enquiry in which we produce more but understand less. By analysing the appeal of these tools, we provide a framework for advancing discussions of responsible knowledge production in the age of AI.

Acute right opercular stroke-associated polyopic heautoscopy and hallucinations caused by disconnection to the inferior parietal lobule through the superior longitudinal fasciculus III: A single case study.

Illusory neuropsychiatric symptoms such as hallucinations or the feeling of a presence (FOP) can occur in diffuse brain lesion or dysfunction, in psychiatric diseases as well as in healthy individuals. Their occurrence due to focal brain lesions is rare, most probably due to underreporting, which limits progress in understanding their underlying mechanisms and anatomical determinants. In this single case study, an 86-year-old patient experienced, in the context of an acute right central opercular ischemic stroke, visual hallucinatory symptoms (including palinopsia), differently lateralized auditory hallucinations and FOP. This unusual clinical constellation could be precisely documented and illustrated while still present, allowing a realistic and immersive visual experience validated by the patient. The acute stroke appeared to be their most plausible cause (after exclusion of other etiologies). Furthermore, accurate analysis of tractographic data suggested that disruption in the posterior bundle of the superior longitudinal fasciculus connecting the stroke lesion to the inferior parietal lobule was the anatomical substrate explaining the FOP and, indirectly, also hallucinations through whiter matter involvement, in coherence with existing literature. We could finally elaborate on symptoms taxonomy and phenomenology (e.g., polyopic heautoscopy, hallucinatory FOP, etc), and on patient's remarkable distancing from them (with some therapeutic implications supported by plausibly engaged mechanisms). This case not only authentically enriched the description of such rare combination of heterogenous illusory symptoms through this novel visualization-based reporting approach, but disclosed an unrevealed anatomo-clinical link relating all of them to the acute stroke lesion through an association fiber, thereby contributing to the understanding of these intriguing symptoms and their determinants.

Breaking presence in Immersive Virtual Reality toward behavioral and emotional engagement.

BACKGROUND AND OBJECTIVE: Many recent studies in virtual reality (VR) have managed the sense of Presence to assess the suitability of their designs, mainly when focused on learning goals that require high user engagement, such as in serious games for psychomotor training. However, the place and plausibility illusions needed to promote Presence are achieved by combining different VR-based design cues, and their individual contribution to preserving the Presence's engagement/involvement component is still unclear. This article explored the single effect of breaking the sense of Presence per VR factor, i.e., removing VR cues related to Social Presence (human interactions), Self-Presence (embodiment), and Physical Presence (Scenario realism). METHODS: Thirty-three participants were asked to play an immersive VR simulation of an arcade game three times by experiencing a stepped Break of Illusion in one of the VR factors, i.e., while two factors were kept high, the remaining one was reduced to a low and null (hypothetical) level. The game difficulty was fixed after assessing each person's skills. RESULTS: Results showed that psychophysiology indicators (heart rate and skin conductance) were not affected by the level of illusion, whereas exercise intensity was significantly higher with low body and social presence-based conditions. Moreover, skin conductance was lower in the Social-presence group, which suggests that perspiration is only affected by breaks in realism (scenario and body representations). Based on the obtained evidence, we proposed some guidelines for adapting the design of immersive virtual environments through Breaks in Presence, mainly by changing the realism of the scenario and body representation depending on the skin conductance or the interaction with virtual humans depending on exercise intensity.

Stations Along the Via Dolorosa Towards Good-Enough Endings.

This article focuses on the prevailing aspiration to reach a "good-enough ending" in analysis, a concept that is partly realistic and partly illusional. I discuss some of the obstacles that interfere with achieving this yearned for goal, and lead to endings that are far from the misleading illusion of the good-enough termination, that many of us believe we have achieved and are many more than it is commonly reported. I describe characteristics, obstacles, blockages, dreads within the analysand, within the analyst and in the space in between, which lead to endings which are far from good enough, by any criteria we might choose. These obstacles include the failure to distinguish between "real" versus "similar to"; emotional excess; emptying out of internal resources and toxemia of therapy/analysis; a fascination with certain levels of mind versus a neglect of others; osmotic pressure for oneness and the terror of perfection; and malignant nostalgia. Reflecting on such complex facets in the analytic process is relevant not only for a deeper understanding of illusions that we and our analysands hold with regard to endings, but also, implicitly, to the understanding of illusions, beliefs, and myths we and our patients have regarding beginnings.

The overlooked role of unisensory precision in multisensory research.

Zhu et al. present an alternative explanation for the weaker multisensory illusions in football goalkeepers compared with outfielders and non-athletes, showing that better unisensory precision in goalkeepers can also account for this effect.

Disambiguating vision with sound.

An important task for the visual system is to identify and segregate objects from background. Figure-ground illusions, such as Edgar Rubin's bistable 'vase-faces illusion'1, make the point clearly: we see either a central vase or lateral faces, alternating spontaneously, but never both images simultaneously. The border is perceptually assigned to either faces or vase, which become figure, the other shapeless background2. The stochastic alternation between figure and ground probably reflects mutual inhibitory processes that ensure a single perceptual outcome3. Which shape dominates perception depends on many factors, such as size, symmetry, convexity, enclosure, and so on, as well as attention and intention4. Here we show that the assignment of the visual border can be strongly influenced by auditory input, far more than is possible by voluntary intention. VIDEO ABSTRACT.

Changes in spatial self-consciousness elicit grid cell-like representation in the entorhinal cortex.

Grid cells in the entorhinal cortex (EC) encode an individual's location in space, integrating both environmental and multisensory bodily cues. Notably, body-derived signals are also primary signals for the sense of self. While studies have demonstrated that continuous application of visuo-tactile bodily stimuli can induce perceptual shifts in self-location, it remains unexplored whether these illusory changes suffice to trigger grid cell-like representation (GCLR) within the EC, and how this compares to GCLR during conventional virtual navigation. To address this, we systematically induced illusory drifts in self-location toward controlled directions using visuo-tactile bodily stimulation, while maintaining the subjects' visual viewpoint fixed (absent conventional virtual navigation). Subsequently, we evaluated the corresponding GCLR in the EC through functional MRI analysis. Our results reveal that illusory changes in perceived self-location (independent of changes in environmental navigation cues) can indeed evoke entorhinal GCLR, correlating in strength with the magnitude of perceived self-location, and characterized by similar grid orientation as during conventional virtual navigation in the same virtual room. These data demonstrate that the same grid-like representation is recruited when navigating based on environmental, mainly visual cues, or when experiencing illusory forward drifts in self-location, driven by perceptual multisensory bodily cues.

Perceptual uncertainty explains activation differences between audiovisual congruent speech and McGurk stimuli.

Face-to-face communication relies on the integration of acoustic speech signals with the corresponding facial articulations. In the McGurk illusion, an auditory /ba/ phoneme presented simultaneously with a facial articulation of a /ga/ (i.e., viseme), is typically fused into an illusory 'da' percept. Despite its widespread use as an index of audiovisual speech integration, critics argue that it arises from perceptual processes that differ categorically from natural speech recognition. Conversely, Bayesian theoretical frameworks suggest that both the illusory McGurk and the veridical audiovisual congruent speech percepts result from probabilistic inference based on noisy sensory signals. According to these models, the inter-sensory conflict in McGurk stimuli may only increase observers' perceptual uncertainty. This functional magnetic resonance imaging (fMRI) study presented participants (20 male and 24 female) with audiovisual congruent, McGurk (i.e., auditory /ba/ + visual /ga/), and incongruent (i.e., auditory /ga/ + visual /ba/) stimuli along with their unisensory counterparts in a syllable categorization task. Behaviorally, observers' response entropy was greater for McGurk compared to congruent audiovisual stimuli. At the neural level, McGurk stimuli increased activations in a widespread neural system, extending from the inferior frontal sulci (IFS) to the pre-supplementary motor area (pre-SMA) and insulae, typically involved in cognitive control processes. Crucially, in line with Bayesian theories these activation increases were fully accounted for by observers' perceptual uncertainty as measured by their response entropy. Our findings suggest that McGurk and congruent speech processing rely on shared neural mechanisms, thereby supporting the McGurk illusion as a valid measure of natural audiovisual speech perception.

Reduced influence of perceptual context in mild traumatic brain injury is not an illusion.

Perceptual grouping is impaired following mild traumatic brain injury (mTBI). This may affect visual size perception, a process influenced by perceptual grouping abilities. We conducted two experiments to evaluate visual size perception in people with self-reported history of mTBI, using two different size-contrast illusions: the Ebbinghaus Illusion (Experiment 1) and the Müller-Lyer illusion (Experiment 2). In Experiment 1, individuals with mTBI and healthy controls were asked to compare the size of two target circles that were either the same size or different sizes. The target circles appeared by themselves (no-context condition), or were surrounded by smaller or larger circles (context condition). Similar levels of accuracy were evident between the groups in the no-context condition. However, size judgements by mTBI participants were more accurate in the context condition, suggesting that they processed the target circles separately from the surrounding circles. In Experiment 2, individuals with mTBI and healthy controls judged the length of parallel lines that appeared with arrowheads (context condition) or without arrowheads (no context condition). Consistent with Experiment 1, size judgements by mTBI participants were more accurate than size judgements by control participants in the context condition. These findings suggest that mTBI influences size perception by impairing perceptual grouping of visual stimuli in near proximity.

Dexamphetamine increased speech and visual unimodal illusions in healthy participants without affecting temporal binding window.

OBJECTIVE: Stimuli received beyond a very short timeframe, known as temporal binding windows (TBWs), are perceived as separate events. In previous audio-visual multisensory integration (McGurk effect) studies, widening of TBWs has been observed in people with schizophrenia. The present study aimed to determine if dexamphetamine could increase TBWs in unimodal auditory and unimodal visual illusions that may have some validity as experimental models for auditory and visual hallucinations in psychotic disorders. METHODS: A double-blind, placebo-controlled, counter-balanced crossover design with permuted block randomisation for drug order was followed. Dexamphetamine (0.45 mg/kg, PO, q.d.) was administered to healthy participants. Phantom word illusion (speech illusion) and visual-induced flash illusion/VIFI (visual illusion) tests were measured to determine if TBWs were altered as a function of delay between stimuli presentations. Word emotional content for phantom word illusions was also analysed. RESULTS: Dexamphetamine significantly increased the total number of phantom words/speech illusions (p < 0.01) for pooled 220-1100 ms ISIs in kernel density estimation and the number of positive valence words heard (beta = 2.20, 95% CI [1.86, 2.55], t = 12.46, p < 0.001) with a large effect size (std. beta = 1.05, 95% CI [0.89, 1.22]) relative to placebo without affecting the TBWs. For the VIFI test, kernel density estimation for pooled 0-801 ms ISIs showed a significant difference (p < 0.01) in the data distributions of number of target flash (es) perceived by participants after receiving dexamphetamine as compared with placebo. CONCLUSIONS: Overall, healthy participants who were administered dexamphetamine (0.45 mg/kg, PO, q.d.) experienced increases in auditory and visual illusions in both phantom word illusion and VIFI tests without affecting their TBWs.