Perceptual States Research Articles

Changes in electrophysiological aperiodic activity during cognitive control in Parkinson’s disease

Abstract Cognitive symptoms in Parkinson’s disease are common and can significantly affect patients’ quality of life. Therefore, there is an urgent clinical need to identify a signature derived from behavioural and/or neuroimaging indicators that could predict which patients are at increased risk for early and rapid cognitive decline. Recently, converging evidence identified that aperiodic activity of the EEG reflects meaningful physiological information associated with age, development, cognitive and perceptual states or pathologies. In this study, we aimed to investigate aperiodic activity in Parkinson’s disease during cognitive control and characterize its possible association with behaviour. Here, we recorded high-density EEG in 30 healthy controls and 30 Parkinson’s disease patients during a Simon task. We analysed task-related behavioural data in the context of the activation–suppression model and extracted aperiodic parameters (offset, exponent) at both scalp and source levels. Our results showed lower behavioural performances in cognitive control as well as higher offsets in patients in the parieto-occipital areas, suggesting increased excitability in Parkinson’s disease. A small congruence effect on aperiodic parameters in pre- and post-central brain areas was also found, possibly associated with task execution. Significant differences in aperiodic parameters between the resting-state, pre- and post-stimulus phases were seen across the whole brain, which confirmed that the observed changes in aperiodic activity are linked to task execution. No correlation was found between aperiodic activity and behaviour or clinical features. Our findings provide evidence that EEG aperiodic activity in Parkinson’s disease is characterized by greater offsets, and that aperiodic parameters differ depending on arousal state. However, our results do not support the hypothesis that the behaviour-related differences observed in Parkinson’s disease are related to aperiodic changes. Overall, this study highlights the importance of considering aperiodic activity contributions in brain disorders and further investigating the relationship between aperiodic activity and behaviour.

Dynamic predictive templates in perception

Hallucinations are vivid and transient experiences of objects, such as images or sounds, that occur in the absence of a corresponding stimulus.1,2,3,4,5,6,7,8,9 To understand the neurocomputational mechanisms of hallucinations, cognitive neuroscience has focused on experiments that induce false alarms (FAs) in healthy participants,1,2,3,4,5,9 psychosis-prone individuals,1,3,4 and patients diagnosed with schizophrenia.5 FAs occur when participants make decisions about difficult-to-detect stimuli and indicate the presence of a signal that was, in fact, not presented. Since FAs are, at heart, reports, they must meet two criteria to serve as an experimental proxy for hallucinations: first, FAs should reflect perceptual states that are characterized by specific contents10,11,12 (criterion 1). Second, FAs should occur on a timescale compatible with the temporal dynamics of hallucinations13,14 (criterion 2). In this work, we combined a classification image approach15 with hidden Markov models16 to show that FAs can match the perceptual and temporal characteristics of hallucinations. We asked healthy human participants to discriminate visual stimuli from noise and found that FAs were more likely to occur during an internal mode of sensory processing, a minute-long state of the brain during which perception is strongly biased toward previous experiences17 (serial dependency). Our results suggest that hallucinations are driven by dynamic predictive templates that transform noise into transient, coherent, and meaningful perceptual experiences.

Verbal Perceptual Prompts Facilitate Children's Sensitivity to False Beliefs.

False belief understanding is always regarded as a milestone of Theory of Mind (ToM), which is an important aspect of social intelligence. Recently, some researchers have suggested the existence of two ToM systems in individuals: one that explicitly guides false belief understanding and another that implicitly directs sensitivity to false beliefs. However, studies on sensitivity to false beliefs have encountered challenges with replicability, and the factors influencing the manifestation of sensitivity to false beliefs remain to be explored. Based on the anticipatory looking task, we investigated whether verbal perceptual prompts could improve children's performance of sensitivity to false beliefs. Fifty-eight children aged 5 to 6 were randomly assigned tasks with or without verbal perceptual prompts, involving verbal descriptions and explanations of the protagonist's perceptual state. The findings showed that verbal perceptual prompts could slightly reduce children's propensity to look at the actual location of the object in false belief situations and increase the likelihood of exhibiting accurate anticipatory looking patterns across false belief and true belief situations. The results suggest that children's sensitivity to false beliefs may be situation-dependent, yet further investigation is needed to determine which situational factors can most effectively trigger robust sensitivity to false beliefs in children. The results enlighten educational practice, indicating that introducing cues in social environments that convey insights into others' mental states, akin to the use of learning scaffolding, is advantageous for the development of children's social cognitive abilities.

Parallel Interactions Between Linguistic and Contextual Factors in Bilinguals

AbstractThe necessity for introducing interactionist and parallelism approaches in different branches of cognitive science emerged as a reaction to classical sequential stage‐based models. Functional psychological models that emphasized and explained how different components interact, dynamically producing cognitive and perceptual states, influenced multiple disciplines. Chiefly among them were experimental psycholinguistics and the many applied areas that dealt with humans’ ability to process different types of information in different contexts. Understanding how bilinguals represent and process verbal and visual input, how their neural and psychological states facilitate such interactions, and how linguistic and nonlinguistic processing overlap, has now emerged as an important area of multidisciplinary research. In this article, we will review available evidence from different language‐speaking groups of bilinguals in India with a focus on situational context. In the discussion, we will address models of language processing in bilinguals within a cognitive psychological approach with a focus on existent models of inhibitory control. The paper's stated goal will be to show that the parallel architecture framework can serve as a theoretical foundation for examining bilingual language processing and its interface with external factors such as social context.

Unveiling the odor representation in the inner brain of Drosophila through compressed sensing

The olfaction begins when odorant molecules stimulate a finite number of receptor types in the olfactory neurons. According to the recent connectomics data of the olfactory system, the olfactory neural circuit is multilayered and there is an overall dimensionality reduction from the input to output layer. Compressed sensing (CS) is an algorithm that enables the recovery of high-dimensional signals from the data compressed in a lower dimension when the representation of such signals is sufficiently sparse. By analyzing the recent connectomics data, we find that the organization of the olfactory system effectively satisfies the necessary conditions for CS to work. The neural activity profile of projection neurons (PNs) can be faithfully recovered from a low-dimensional response profile of mushroom body output neurons (MBONs), which can be reconstructed using the electrophysiological recordings of a wide range of odorants. By leveraging the residuals calculated between the measured and the predicted MBON responses, we visualize the perceptual odor space using the residual spectrum and discuss the differentiability of an odor from others. Our study highlights the sparse coding of odor to the receptor space as an essential component for odor identifiability, clarifying the principles underlying the concentration-dependent odor percept. Further, simultaneous exposure of the olfactory system to many different odorants saturates the neural activity profile of PNs, significantly degrading the capacity of signal recovery and resulting in a perceptual state analogous to “olfactory white.” Our study applying CS to the real connectomics data encompassing the neural circuitry from PNs to MBONs via Kenyon cells provides quantitative insights into the neural signal processing and odor representation in the inner brain of . Published by the American Physical Society 2024

Reality testing and metacognition

ABSTRACT Reality testing is the process by which we distinguish our own perceptual states from imagination or episodic memory. I argue that reality testing is a metacognitive process. Since reality testing is also accomplished by creatures who lack mental state concepts, it follows that reality testing is a nonconceptual metacognitive process. I also provide prima facie evidence that reality testing is a necessary condition for prototypical cognitive states like belief. It follows that metacognition is phylogenetically and logically prior to cognition in many cases.

The Non-Arbitrary Link between Feeling and Value: A Psychosemantic Challenge for the Perceptual Theory of Emotion

This essay raises a challenge for the perceptual theory of emotion. According to the perceptual theory, emotions are perceptual states that represent values. But if emotions represent values, something should explain why. In virtue of what do emotions represent the values they do? A psychosemantics would answer this, and that’s what the perceptual theorist owes us. To date, however, the only perceptual theorist to attempt a psychosemantics for emotion is Jesse Prinz. And Prinz’s theory, I argue, faces an important difficulty: It makes the pairing of any given emotion with its respective value entirely arbitrary. But that’s a problem. It seems—and this is a major contention of this essay—that an emotion, in virtue of how it feels, bears a natural or non-arbitrary link to the value it represents. And this datum makes it all the more difficult to provide a viable psychosemantics for the evaluative content of emotion.

Practical perceptual representations: a contemporary defense of an old idea

According to ‘orthodox’ representationalism, perceptual states possess constitutive veridicality (truth, accuracy, or satisfaction) conditions. Typically, philosophers who deny orthodox representationalism endorse some variety of anti-representationalism. But we argue that these haven’t always been, and needn’t continue to be, the only options. Philosophers including Descartes, Malebranche and Helmholtz appear to have rejected orthodox representationalism while nonetheless endorsing perceptual representations of a fundamentally practical kind not captured by orthodox representationalism. Moreover, we argue that the perceptual science called on by contemporary philosophers to defend orthodox representationalism instead motivates a return to this older view, and we suggest that contemporary philosophers may conceptualize fundamentally practical perceptual representations as ‘de agendo’ representations, a species of representation that has constitutive appropriateness rather than veridicality conditions.

How the inner repetition of a desired perception changes actual tactile perception

Autosuggestion is a cognitive process where the inner repetition of a thought actively influences one’s own perceptual state. In spite of its potential benefits for medical interventions, this technique has gained little scientific attention so far. Here, we took advantage of the known link between intensity and frequency perception in touch (‘Békésy effect’). In three separate experiments, participants were asked to modulate the perceived intensity of vibrotactile stimuli at the fingertip through the inner reiteration of the thought that this perception feels very strong (Experiment 1, n = 19) or very weak (Experiments 2, n = 38, and 3, n = 20), while they were asked to report the perceived frequency. We show that the task to change the perceived intensity of a tactile stimulus via the inner reiteration of a thought modulates tactile frequency perception. This constitutes the first experimental demonstration that an experimental design that triggers autosuggestion alters participants’ tactile perception using a response orthogonal to the suggested variable. We discuss whether this cognitive process could be used to influence the perception of pain in a clinical context.

Quantum-Inspired Neural Network Model of Optical Illusions

Ambiguous optical illusions have been a paradigmatic object of fascination, research and inspiration in arts, psychology and video games. However, accurate computational models of perception of ambiguous figures have been elusive. In this paper, we design and train a deep neural network model to simulate human perception of the Necker cube, an ambiguous drawing with several alternating possible interpretations. Defining the weights of the neural network connection using a quantum generator of truly random numbers, in agreement with the emerging concepts of quantum artificial intelligence and quantum cognition, we reveal that the actual perceptual state of the Necker cube is a qubit-like superposition of the two fundamental perceptual states predicted by classical theories. Our results finds applications in video games and virtual reality systems employed for training of astronauts and operators of unmanned aerial vehicles. They are also useful for researchers working in the fields of machine learning and vision, psychology of perception and quantum–mechanical models of human mind and decision making.

The Effects of Low-Load Squat Jump and Maximal Isometric Priming Exercise on Muscular Performance and Perceptual State.

Harrison, PW, James, LP, Jenkins, DG, McGuigan, MR, Holmberg, PM, and Kelly, VG. The effects of low-load squat jump and maximal isometric priming exercise on muscular performance and perceptual state. J Strength Cond Res 38(1): 1-9, 2024-The aim of this study was to examine responses at 3 and 27 hours after low-load jump squat (LL) and maximal isometric half-squat (ISO) priming stimuli. Fifteen resistance-trained males performed LL (4 × 3 at 20% 1 repetition maximum [1RM]), ISO (4 × 3 seconds), and control (CON) activities (standardized warm-up) in a randomized and counterbalanced order. Countermovement jump (CMJ) and isometric midthigh pull tests were conducted to assess performance changes after priming and CON activities. No clear changes in CMJ measures were found after priming activities compared with CON. However, small effect size improvements were found after priming stimuli completed on the same day. A 2.9% decrease in concentric phase duration (CI = 0.3-5.9, p = 0.333, Cliff's delta = -0.156) and a 9.1% increase in RSImod (CI = 0.2-12.3, p = 0.151, Cliff's delta = -0.218) occurred at 3 hours after LL compared with CON. Braking phase duration (CI = 0.8-10.6, p = 0.333, Cliff's delta = -0.213) was 2.9% shorter at 3 hours after ISO compared with CON. No clear changes in isometric peak force occurred after priming activities compared with CON. Additionally, questionnaires were completed to assess perceptual state and perceived effectiveness of the priming stimulus to influence performance. An increase in the "effect of activity" was perceived at 3 hours after LL and ISO (p = 0.013-0.044, Cliff's delta = 0.578-0.6) and at 27 hours after ISO (p = 0.99, Cliff's delta = 0.173) compared with CON. An increase in "muscular heaviness" was also reported at 3 hours after ISO compared with CON (p = 0.199, Cliff's delta = 0.320). The collective findings suggest limited benefits over the day after LL and ISO priming stimuli. However, as there was substantial variation in individual responses, the relative nature of priming responses should be considered when prescribing similar strategies in practical environments.

Does Moderate-Load Priming Activity Influence Maximal Upper-Body Performance and Perceptual State?

Harrison, PW, Kelly, VG, Jenkins, DG, McGuigan, MR, Holmberg, PM, and James, LP. Does moderate-load priming activity influence maximal upper-body performance and perceptual state?. J Strength Cond Res 37(11): e581-e587, 2023-The results of previous research indicate that resistance exercise "priming" may improve strength-power measures within 48 hours after their completion. Although researchers have primarily examined performance responses after lower-body priming stimuli, investigations examining the effects of upper-body resistance priming exercises are presently limited. Therefore, the aim of this study was to examine upper-body pushing and pulling performance in addition to perceptual responses 3 and 27 hours after moderate-load (ML) upper-body resistance priming exercise. Fourteen resistance-trained men were assigned to complete ML priming (4 × 3 bench press and bench pull at 65% 1RM [repetition maximum]) and control (rest) protocols in a randomized and counterbalanced order. Peak velocity during the bench throw and bench pull tests involving different loads (25, 50, and 75% 1RM) showed no practical change at 3 and 27 hours after the priming session (p = 0.216-0.99, Cliff's d = -0.041 to 0.225). Small effect size increases in perceptual measures ("physical feeling," "physical performance," "aggression" [p = 0.400-0.553, Cliff's d = 0.183-0.201], and "muscular heaviness" [p = 0.178, Cliff's d = 0.231]) were found at 3 hours postpriming. A moderate practical increase was observed in perceived "physical feeling" compared with control (p = 0.385, Cliff's d = 0.349) in addition to small effect size increases in perceived "physical performance" and "aggression" (Cliff's d = 0.243-0.290) at 27 hours after priming activities. These results indicate that upper-body strength-power changes within 27 hours after ML upper-body resistance exercise priming are not practically meaningful.

No relationships between frequencies of mind-wandering and perceptual rivalry.

Our minds frequently wander from a task at hand. This mind-wandering reflects fluctuations in our cognitive states. The phenomenon of perceptual rivalry, in which one of the mutually exclusive percepts automatically switches to an ambiguous sensory input, is also known as fluctuations in our perceptual states. There may be possible relationships between the mind-wandering and perceptual rivalry, given that physiological responses such as fluctuations in pupil diameter, which is an index of attentional/arousal states, are related to the occurrence of both phenomena. Here, we investigate possible relationships between mind-wandering and perceptual rivalry by combining experimental and questionnaire methods in an online research protocol. In Study 1, we found no statistically significant relationships between subjective mind-wandering tendencies measured by questionnaires and frequencies of perceptual rivalry for Necker-cube or structure-from-motion stimuli. Study 2 replicated the results of Study 1 and further confirmed no statistically significant relationships between behavioral measurements of mind-wandering tendencies estimated by sustained attention to response task and frequencies of perceptual rivalry. These findings suggest that mind-wandering and perceptual rivalry would be based on different mechanisms, possibly higher-level cognitive and lower-level perceptual ones.

Evidence for Reduced Sensory Precision and Increased Reliance on Priors in Hallucination-Prone Individuals in a General Population Sample.

There is increasing evidence that people with hallucinations overweight perceptual beliefs relative to incoming sensory evidence. Past work demonstrating prior overweighting has used simple, nonlinguistic stimuli. However, auditory hallucinations in psychosis are often complex and linguistic. There may be an interaction between the type of auditory information being processed and its perceived quality in engendering hallucinations. We administered a linguistic version of the conditioned hallucinations (CH) task to an online sample of 88 general population participants. Metrics related to hallucination-proneness, hallucination severity, stimulus thresholds, and stimulus detection rates were collected. Data were used to fit parameters of a Hierarchical Gaussian Filter (HGF) model of perceptual inference to determine how latent perceptual states influenced task behavior. Replicating past results, higher CH rates were observed both in those with recent hallucinatory experiences as well as participants with high hallucination-proneness; CH rates were positively correlated with increased prior weighting; and increased prior weighting was related to hallucination severity. Unlike past results, participants with recent hallucinatory experiences as well as those with higher hallucination-proneness had higher stimulus thresholds, lower sensitivity to stimuli presented at the highest threshold, and had lower response confidence, consistent with lower precision of sensory evidence. We replicate the finding that increased CH rates and recent hallucinations correlate with increased prior weighting using a linguistic version of the CH task. Results support a role for reduced sensory precision in the interplay between prior weighting and hallucination-proneness.

Al-Shaʿrānī’s Defence of Ibn ʿArabī in Context: Interpreting ‘the Oneness of Existence’ (waḥdat al-wujūd) as Experiential Oneness

Abstract The sixteenth-century Egyptian scholar ʿAbd al-Wahhāb al-Shaʿrānī was a prominent Shāfiʿī jurist of his time as well as an ardent supporter of Ibn ʿArabī; he played an important role in popularising Ibn ʿArabī’s teaching, which were then considered highly controversial. However, in current scholarship, al-Shaʿrānī’s defence of Ibn ʿArabī’s work is often dismissed as arbitrary and inconsistent. The present study seeks to challenge this negative, albeit unanimous, view of al-Shaʿrānī’s work, by demonstrating that his reading of Ibn ʿArabī is in fact founded upon a carefully thought-out methodology. By detailing the views of both pro- and anti-Ibn ʿArabī scholars, I first shed light on the classification of mystics that these scholars shared in common: heretical proponents of the oneness of existence (waḥdat al-wujūd) and legitimate advocates of the oneness of witnessing (waḥdat al-shuhūd) – which I describe in the study as ‘experiential oneness’. Secondly, by referring to al-Shaʿrānī’s hitherto unstudied texts, I discuss how he adapted the same framework of categorising the mystics with the aim of defending Ibn ʿArabī. I demonstrate how al-Shaʿrānī interpreted the ontological doctrine of the oneness of existence as a psychological, perceptual state of experiential oneness, thereby promoting Ibn ʿArabī as an exponent of experiential oneness. Furthermore, I argue that by building upon this reading method of experiential oneness, al-Shaʿrānī recontextualised some of Ibn ʿArabī’s famous tenets, such as divine self-manifestation (tajallī) and anthropomorphism (tashbīh). By doing so, al-Shaʿrānī combined Ibn ʿArabī’s teachings with his own mystical worldview, which is based on experiential oneness. I conclude that al-Shaʿrānī’s approach to Ibn ʿArabī was fittingly formulated against the intellectual trends of fifteenth- and sixteenth-century Egypt, and that al-Shaʿrānī was an innovative and unique defender of Ibn ʿArabī’s thought.

The effect of the peristimulus alpha phase on visual perception through real-time phase-locked stimulus presentation.

The alpha phase has been theorized to reflect fluctuations in cortical excitability and thereby impose a cyclic influence on visual perception. Despite its appeal, this notion is not fully substantiated, as both supporting and opposing evidence has been recently reported. In contrast to previous research, this study examined the effect of the peristimulus instead of prestimulus phase on visual detection through a real-time phase-locked stimulus presentation approach. Specifically, we monitored phase data from magnetoencephalography (MEG) recordings over time, with a newly developed algorithm based on adaptive Kalman filtering. This information guided online presentations of masked stimuli that were phased-locked to different stages of the alpha cycle while healthy humans concurrently performed detection tasks. Behavioral evidence showed that the overall detection rate did not significantly vary according to the four predetermined peristimulus alpha phases. Nevertheless, the follow-up analyses highlighted that the phase at 90° relative to 180° likely enhanced detection. Corroborating neural parietal activity showed that early interaction between alpha phases and incoming stimuli orchestrated the neural representation of the hits and misses of the stimuli. This neural representation varied according to the phase and in turn shaped the behavioral outcomes. In addition to directly investigating to what extent fluctuations in perception can be ascribed to the alpha phases, this study suggests that phase-dependent perception is not as robust as previously presumed, and might also depend on how the stimuli are differentially processed as a result of a stimulus-phase interaction, in addition to reflecting alternations of the perceptual states between phases.Significance statementAlpha activity, a widely observed neural phenomenon, is postulated to be essential for organizing visual perception. However, our previous understanding of the functional relevance of the alpha phase is primarily inferred from the prestimulus or externally entrained phase. This study monitors real-time phase activity and presents stimuli that are phased-locked to different stages of the alpha cycle. This new approach allows us to investigate whether and how the alpha phases, during which stimuli are concurrently presented, directly lead to behavioral and neural changes in perception. Our evidence suggests that the extent to which the alpha phases affect perception depends on an early interaction between the phase and incoming stimuli, which is involved in shaping the perceptual fates of the stimuli.

Hidden Semi-Markov Models-Based Visual Perceptual State Recognition for Pilots.

Pilots' loss of situational awareness is one of the human factors affecting aviation safety. Numerous studies have shown that pilot perception errors are one of the main reasons for a lack of situational awareness without a proper system to detect these errors. The main objective of this study is to examine the changes in pilots' eye movements during various flight tasks from the perspective of visual awareness. The pilot's gaze rule scanning strategy is mined through cSPADE, while a hidden semi-Markov model-based model is used to detect the pilot's visuoperceptual state, linking the correlation between the hidden state and time. The performance of the proposed algorithm is then compared with that of the hidden Markov model (HMM), and the more flexible hidden semi-Markov model (HSMM) is shown to have an accuracy of 93.55%.

Neurophysiological time course of timbre-induced music-like perception.

Traditionally, pitch variation in a sound stream has been integral to music identity. We attempt to expand music's definition, by demonstrating that the neural code for musicality is independent of pitch encoding. That is, pitchless sound streams can still induce music-like perception and a neurophysiological hierarchy similar to pitched melodies. Previous work reported that neural processing of sounds with no-pitch, fixed-pitch, and irregular-pitch (melodic) patterns, exhibits a right-lateralized hierarchical shift, with pitchless sounds favorably processed in Heschl's gyrus (HG), ascending laterally to nonprimary auditory areas for fixed-pitch and even more laterally for melodic patterns. The objective of this EEG study was to assess whether sound encoding maintains a similar hierarchical profile when musical perception is driven by timbre irregularities in the absence of pitch changes. Individuals listened to repetitions of three musical and three nonmusical sound-streams. The nonmusical streams were comprised of seven 200-ms segments of white, pink, or brown noise, separated by silent gaps. Musical streams were created similarly, but with all three noise types combined in a unique order within each stream to induce timbre variations and music-like perception. Subjects classified the sound streams as musical or nonmusical. Musical processing exhibited right dominant α power enhancement, followed by a lateralized increase in θ phase-locking and spectral power. The θ phase-locking was stronger in musicians than in nonmusicians. The lateralization of activity suggests higher-level auditory processing. Our findings validate the existence of a hierarchical shift, traditionally observed with pitched-melodic perception, underscoring that musicality can be achieved with timbre irregularities alone.NEW & NOTEWORTHY EEG induced by streams of pitchless noise segments varying in timbre were classified as music-like and exhibited a right-lateralized hierarchy in processing similar to pitched melodic processing. This study provides evidence that the neural-code of musicality is independent of pitch encoding. The results have implications for understanding music processing in individuals with degraded pitch perception, such as in cochlear-implant listeners, as well as the role of nonpitched sounds in the induction of music-like perceptual states.

Visual assumption and perceptual social bias

ABSTRACT Siegel recently distinguishes between seven possible ways in which our perceptual access to social information can be biased by flawed practice of either individuals or social structures, two of which, namely attention and cognitive penetration, imply that it is the content of perception, as opposed to that of judgments, that is biased. Both attention and cognitive penetration, however, rely on cognitive states imposing top-down influences on perceptual states. As such, perceptual bias resulting from them is to a large extent merely a derivation of cognitive bias. In this paper, I propose another way in which our perception can be biased, namely, as the result of faulty assumptions made by the visual system. Furthermore, I argue that in contrast to cognitive penetration and attentional direction, perceptual bias arising in this way is fundamentally perceptual and does not depend on inputs from one’s cognitive system. This sort of perceptual bias, if it exists, would have important implications for how we conceptualize social bias and pose special challenges to traditional interventions designed to counteract bias.

Spontaneous Necker-cube reversals may not be that spontaneous.

During observation of the ambiguous Necker cube, our perception suddenly reverses between two about equally possible 3D interpretations. During passive observation, perceptual reversals seem to be sudden and spontaneous. A number of theoretical approaches postulate destabilization of neural representations as a pre-condition for reversals of ambiguous figures. In the current study, we focused on possible Electroencephalogram (EEG) correlates of perceptual destabilization, that may allow prediction of an upcoming perceptual reversal. We presented ambiguous Necker cube stimuli in an onset-paradigm and investigated the neural processes underlying endogenous reversals as compared to perceptual stability across two consecutive stimulus presentations. In a separate experimental condition, disambiguated cube variants were alternated randomly, to exogenously induce perceptual reversals. We compared the EEG immediately before and during endogenous Necker cube reversals with corresponding time windows during exogenously induced perceptual reversals of disambiguated cube variants. For the ambiguous Necker cube stimuli, we found the earliest differences in the EEG between reversal trials and stability trials already 1 s before a reversal occurred, at bilateral parietal electrodes. The traces remained similar until approximately 1100 ms before a perceived reversal, became maximally different at around 890 ms (p = 7.59 × 10-6, Cohen's d = 1.35) and remained different until shortly before offset of the stimulus preceding the reversal. No such patterns were found in the case of disambiguated cube variants. The identified EEG effects may reflect destabilized states of neural representations, related to destabilized perceptual states preceding a perceptual reversal. They further indicate that spontaneous Necker cube reversals are most probably not as spontaneous as generally thought. Rather, the destabilization may occur over a longer time scale, at least 1 s before a reversal event, despite the reversal event as such being perceived as spontaneous by the viewer.