Necker Cube Research Articles

Brain networks underlying bistable perception

Bistable stimuli, such as the Necker Cube, demonstrate that experience can change in the absence of changes in the environment. Such phenomena can be used to assess stimulus-independent aspects of conscious experience. The current study used resting state functional magnetic resonance imaging (rs-fMRI) to index stimulus-independent changes in neural activity to understand the neural architecture that determines dominance durations during bistable perception (using binocular rivalry and Necker cube stimuli). Anterior regions of the Superior Parietal Lobule (SPL) exhibited robust connectivity with regions of primary sensorimotor cortex. The strength of this region's connectivity with the striatum predicted shorter dominance durations during binocular rivalry, whereas its connectivity to pre-motor cortex predicted longer dominance durations for the Necker Cube. Posterior regions of the SPL, on the other hand, were coupled to associative cortex in the temporal and frontal lobes. The posterior SPL's connectivity to the temporal lobe predicted longer dominance during binocular rivalry. In conjunction with prior work, these data suggest that the anterior SPL contributes to perceptual rivalry through the inhibition of incongruent bottom up information, whereas the posterior SPL influences rivalry by supporting the current interpretation of a bistable stimulus. Our data suggests that the functional connectivity of the SPL with regions of sensory, motor, and associative cortex allows it to regulate the interpretation of the environment that forms the focus of conscious attention at a specific moment in time.

Individual variability in perceptual switching behaviour is associated with reversal-related EEG modulations

ObjectiveHigh individual variability is frequently observed in multistable perception, but few ERP studies have considered this factor. The present investigation evaluates the relation between individual perceptual switching and the modulation of reversal-related ERP components. MethodsWe used a bistable perception paradigm (Kornmeier and Bach, 2004), consisting of briefly flashed grid of nine Necker cubes, interspersed by a blank screen. The subject’s task was to compare the previous stimulus with the latter one. The number of reversal perceptions was used as a measure of individual perceptual switching behaviour. ResultsAs in previously reported findings, Reversal Negativity (RN, 180–300ms) and Late Positive Component (LPC, 350–600ms) were identified in response to reversal perception. In terms of individual differences, higher reversals were associated with reduced negativity of the RN and enhanced positivity of the LPC. ConclusionThe timing of the present results supports the hypothesis that individual variability in perceptual reversal is associated with different neural activations at later stage of processing, when the neural representation of ambiguous figure must be internalized to produce an appropriate response/behaviour. SignificanceMultistable perception can reveal crucial mechanisms underlying individual perceptual re-organization when inconsistent or incoherent stimuli come from the environment.

Necker’s smile: Immediate affective consequences of early perceptual processes

Current theories assume that perception and affect are separate realms of the mind. In contrast, we argue that affect is a genuine online-component of perception instantaneously mirroring the success of different perceptual stages. Consequently, we predicted that the success (failure) of even very early and cognitively encapsulated basic visual processing steps would trigger immediate positive (negative) affective responses. To test this assumption, simple visual stimuli that either allowed or obstructed early visual processing stages without participants being aware of this were presented briefly. Across 5 experiments, we found more positive affective responses to stimuli that allowed rather than obstructed Gestalt completion at certain early visual stages (Experiments 1–3; briefest presentation 100ms with post-mask), and visual disambiguation in possible vs. impossible Necker cubes (Experiments 4 and 5; briefest presentation 100ms with post-mask). This effect was observed both on verbal preference ratings (Experiments 1, 2, and 4) and as facial muscle responses occurring within 2–4s after stimulus onset (zygomaticus activity; Experiments 3 and 7). For instance, in participants unaware of spatial possibility we found affective discrimination between possible and impossible Necker cubes (the famous Freemish Crate) for 100ms presentation timings, although a conscious discrimination took more than 2000ms (Experiment 4).

The publications and collections of Louis-Albert Necker (1786–1861)

The Swiss geologist and mineralogist Louis-Albert Necker belonged to a family rich in scientific celebrities. Though a professor at the Académie de Genève for 25 years and author of numerous publications, he is mainly remembered today for his description of the “Necker cube” optical illusion and for leaving Geneva to spend the last 20 years of his life in Portree on the Isle of Skye. As a first step towards assessing Necker's contribution to science, a full list of his publications is presented, with comments about their citation in previous bibliographies and about published translations and abridgements. Information about the surviving specimens from his scientific collections, most of which are in the Muséum d'histoire naturelle de Genève, is also presented.

Evidence for Obliqueness of Angles as a Cue to Planar Surface Slant Found in Extremely Simple Symmetrical Shapes

The Necker cube is a striking example for perceptual dominance of 3D over 2D. Object symmetry and obliqueness of angles are co-varying cues that may underlie the perceived slant of Necker cubes. To investigate the power of the oblique-angle cue, slants were judged of extremely simple symmetrical shapes. Slant computations based on an assumption of orthogonality were made for two abutting lines as a function of vertex angle and the slant of the screen. Computed slants were compared with slants judged by six subjects under binocular viewing conditions. Judged slant was highly correlated with slant specified by the oblique angles under an assumption of orthogonality. The contributions of screen cues, including binocular disparity, were negligible. The consistency of the judgments across subjects indicates the assumption of orthogonality as one of the principles underlying slant perception. Necker cubes illustrate that the visual system can disengage unambiguous cues in favor of ambiguous object-symmetry and oblique-angle cues, if the latter indicate very different slants. Selective disengagement of cues may be the mechanism that underlies the success of 2D images in ancient, as well as modern civilizations.

Effect of visual cues on the resolution of perceptual ambiguity in Parkinson's disease and normal aging.

Parkinson's disease (PD) and normal aging have been associated with changes in visual perception, including reliance on external cues to guide behavior. This raises the question of the extent to which these groups use visual cues when disambiguating information. Twenty-seven individuals with PD, 23 normal control adults (NC), and 20 younger adults (YA) were presented a Necker cube in which one face was highlighted by thickening the lines defining the face. The hypothesis was that the visual cues would help PD and NC to exert better control over bistable perception. There were three conditions, including passive viewing and two volitional-control conditions (hold one percept in front; and switch: speed up the alternation between the two). In the Hold condition, the cue was either consistent or inconsistent with task instructions. Mean dominance durations (time spent on each percept) under passive viewing were comparable in PD and NC, and shorter in YA. PD and YA increased dominance durations in the Hold cue-consistent condition relative to NC, meaning that appropriate cues helped PD but not NC hold one perceptual interpretation. By contrast, in the Switch condition, NC and YA decreased dominance durations relative to PD, meaning that the use of cues helped NC but not PD in expediting the switch between percepts. Provision of low-level cues has effects on volitional control in PD that are different from in normal aging, and only under task-specific conditions does the use of such cues facilitate the resolution of perceptual ambiguity.

Perceptual, cognitive, and personality rigidity in Parkinson's disease

Parkinson’s disease (PD) is associated with motor and non-motor rigidity symptoms (e.g., cognitive and personality). The question is raised as to whether rigidity in PD also extends to perception, and if so, whether perceptual, cognitive, and personality rigidities are correlated. Bistable stimuli were presented to 28 non-demented individuals with PD and 26 normal control adults (NC). Necker cube perception and binocular rivalry were examined during passive viewing, and the Necker cube was additionally used for two volitional-control conditions: Hold one percept in front, and Switch between the two percepts. Relative to passive viewing, PD were significantly less able than NC to reduce dominance durations in the Switch condition, indicating perceptual rigidity. Tests of cognitive flexibility and a personality questionnaire were administered to explore the association with perceptual rigidity. Cognitive flexibility was not correlated with perceptual rigidity for either group. Personality (novelty seeking) correlated with dominance durations on Necker passive viewing for PD but not NC. The results indicate the presence in mild-moderate PD of perceptual rigidity and suggest shared neural substrates with novelty seeking, but functional divergence from those supporting cognitive flexibility. The possibility is raised that perceptual rigidity may be a harbinger of cognitive inflexibility later in the disease course.

Special Issue on Bio-inspired Vision Systems

Much of early vision research drew inspirations from what was then known about biological vision. Progress was slow however, and over time machine learning in combination with features selected more on pragmatic grounds took over. Increasingly impressive results seem to justify that approach. The advent of affordable depth cameras further moved the field (certainly in robotics) away from biological considerations—why bother how the human brain arrives at 3D scene interpretations when the 3D data is just readily available? Not all problems simply vanish however by throwing novel sensors and heavy machine learning at them. 3D sensors really only give 2.5D data. The backside, as well as sensor artefacts coming from physical limitations, still need to be filled in. And how meaning can be attached to visual percepts—2D or 3D—can not simply be explained by learning from large hand labelled data bases. So there is still a lot to learn from biological vision systems. How to arrive at a sufficiently clear (whatever that means in detail) interpretation of the scene from several patchy cues? How to tightly couple vision to other aspects of a cognitive system? What is the right level of abstraction for representations? In this issue we present current work in bio-inspired vision systems and explore the possibilities offered by new findings in biological vision systems as well as latest developments in machine vision. The survey article by Kruger et al. starts with a short history of biologically motivated methods in computer vision and lists several open problems in current computer vision research. This is contrasted with key findings from the primate’s visual system, and the article goes on to argue for rethinking the potential impact of biologically motivated methods in the light of these new findings. One of these findings is the importance of shared intermediate level representations. Rodriguez-Sanchez et al. discuss in their article the role such intermediate-level representations play in achieving higher-level object abstraction and present recent developments in the neural computational modeling of intermediate-level shape processing. Another important finding is that biological vision seems to maintain several possibly conflicting (think: Necker Cube) interpretations of a visual scene and avoid early commitment to a single solution. This is explored in M. Zillich (&) Automation and Control Institute, Vienna University of Technology, Vienna, Austria e-mail: zillich@acin.tuwien.ac.at

Temporal Processing in Bistable Perception of the Necker Cube.

Perception of ambiguous figures is unstable and alternates repeatedly between possible interpretations. Some approaches to explaining this phenomenon have, so far, assumed low-level bottom-up mechanisms like adaptation and mutual inhibition of underlying neural assemblies. In contrast, less precise top-down approaches assume high-level attentional control mechanisms generalised across sensory modalities. In the current work we focused on specific aspects of the top-down approach. In a first study we used dwell times (periods of transiently stable percepts) and the parameters of dwell time distribution functions to compare the dynamics of perceptual alternations between visual (Necker cube) and auditory ambiguity (verbal transformation effect). In a second study we compared the endogenous alternation dynamics of the Necker cube with parameters from two attention tasks with different regimes of temporal dynamics. The first attention task (d2) is characterised by endogenous self-paced dynamics, similar to the dynamics underlying perceptual alternations of ambiguous figures, and we found clear correlations between dwell time parameters (Necker cube) and processing speed (d2 task). The temporal dynamics of the second (go/no-go) attention task, in contrast, are exogenously governed by the stimulus protocol, and we found no statistically significant correlation with the Necker cube data. Our results indicate that both perceptual instability and higher-level attentional tasks are linked to endogenous brain dynamics on a global coordinating level beyond sensory modalities.

Does walking in nature restore directed attention?

Event Abstract Back to Event Does walking in nature restore directed attention? Rachel Richardson1* and Alison Bowling1 1 Southern Cross University, Psychology, School of Health and Human Sciences, Australia Aims: Mental fatigue is commonly understood and experienced as mental exhaustion, irritability and foggy thinking. Research indicates mental fatigue is indicative of depleted directed attention resources. Thus, restoration of directed attention is thought to alleviate mental fatigue. This research sought to determine if walking in nature compared to walking on a treadmill provided enhanced performance on tasks of directed attention. Method: Twenty-two participants completed a 30-min walk on a treadmill and a walk in the local Botanic Garden on separate days. Two directed attention tasks (Rapid Visual Information Processing (RVIP) and Necker Cube reversal task) were conducted both before and after each walk as well as a Perceived Arousal Scale and a Positive and Negative Affect Schedule. Results: Total hits and sensitivity to a target on a RVIP task improved significantly in both locations F(1, 20) = 11.892, p = .003, F(1, 20) = 12.364, p = .002 respectively. However, there was no significant difference between the nature walk and the treadmill walk. Significant order effects were found for sensitivity to targets pre/post walks, F(1, 19) = 10.309, p = .005 and F(1, 19) = 8.578, p = .009 respectively. Necker cube baseline scores indicated a significant reduction in reversals after 30 minutes of walking in both locations. Arousal was higher overall in the nature walk compared to the treadmill walk, F(1, 20) = 11.626, p = .003. Conclusions: No evidence was obtained to suggest that walking in nature leads to improved directed attention compared to walking on a treadmill. Results indicate that improvements were due to significant learning affects. The significantly higher overall score on the arousal scale in the natural environment suggests that participants were more alert in this environment. Keywords: Mental Fatigue, nature, directed attention, Attention Restoration Theory Conference: 12th Annual Psychology Research Conference, 2015, Coffs Harbour, Australia, 25 Sep - 26 Sep, 2015. Presentation Type: Research Topic: Psychology Citation: Richardson R and Bowling A (2015). Does walking in nature restore directed attention?. Front. Psychol. Conference Abstract: 12th Annual Psychology Research Conference, 2015. doi: 10.3389/conf.fpsyg.2015.66.00018 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Sep 2015; Published Online: 23 Sep 2015. * Correspondence: Ms. Rachel Richardson, Southern Cross University, Psychology, School of Health and Human Sciences, Coffs Harbour, NSW, 2450, Australia, r.richardson.15@student.scu.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Rachel Richardson Alison Bowling Google Rachel Richardson Alison Bowling Google Scholar Rachel Richardson Alison Bowling PubMed Rachel Richardson Alison Bowling Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

THE PERCEPTION OF AMBIGUOUS IMAGES AS A QUANTUM INFORMATION PROCESS

A simulation of the dynamic perception of the Necker cube in terms of a two level quantum system – e.g. a qubit realized by a Josephson junction or by an electron of spin ½ controlled by magnetic fields – indicates that the neuro-physiological transformation leading, through a symmetry reduction, to perceptual reversal is controlled by the principles of quantum mechanics. A value of the order of 0,32 mJ.s is estimated for the elementary neuro-physiological action simulating the Planck constant at a mesoscopic level. In this interdisciplinary study key concepts are utilized: symmetry, symmetry reduction, self-organization, superposition principle and ambiguity.

The Influence of the Environment on Directed Attention, Blood Pressure and Heart Rate—An Experimental Study Using a Relaxation Intervention

Attention is a basic cognitive function necessary in most daily activities. Beneficial effects on cognitive abilities after exposure to nature have been reported. To explore if relaxation indoors and in nature differently affect directed attention and physiological measures, 51 participants (39 women) were measured on directed attention with the Necker Cube Pattern Control Test before and after a guided progressive relaxation session indoors and outdoors in nature. Additionally, systolic and diastolic blood pressure and heart rate were measured before and after the relaxation. Participants’ environmental preference was explored. The main result showed an environmental effect on directed attention in favour of the natural environment. No similar environmental effect on physiological measures was seen. The results indicate that relaxation in natural environments had a positive effect on directed attention and hence could be an important component for preventive and rehabilitative interventions for stress-related symptoms.

Temporal dynamics of different cases of bi-stable figure-ground perception.

Segmentation of a visual scene in "figure" and "ground" is essential for perception of the three-dimensional layout of a scene. In cases of bi-stable perception, two distinct figure-ground interpretations alternate over time. We were interested in the temporal dynamics of these alternations, in particular when the same image is presented repeatedly, with short blank periods in-between. Surprisingly, we found that the intermittent presentation of Rubin's classical "face-or-vase" figure, which is frequently taken as a standard case of bi-stable figure-ground perception, often evoked perceptual switches during the short presentations and stabilization was not prominent. Interestingly, bi-stable perception of Kanizsa's anomalous transparency figure did strongly stabilize across blanks. We also found stabilization for the Necker cube, which we used for comparison. The degree of stabilization (and the lack of it) varied across stimuli and across individuals. Our results indicate, against common expectation, that the stabilization phenomenon cannot be generally evoked by intermittent presentation. We argue that top-down feedback factors such as familiarity, semantics, expectation, and perceptual bias contribute to the complex processes underlying the temporal dynamics of bi-stable figure-ground perception.

Contextual disambiguation of rotating Necker cubes

Contextual disambiguation of rotating Necker cubes

Left ventricular ejection fraction by real-time three-dimensional echocardiography : The Necker cube for the naive realism of two-dimensional methods.

Despite a staggering technical progress in echocardiography, in daily clinical practice assessment of left ventricular (LV) ejection fraction (EF) is still often done in a rather inaccurate two-dimensional (2D) manner. Real-time three-dimensional echocardiography (RT3DE) provides a more representative realistic view of LV volumes, thereby being the Necker cube for the naive realism of 2D methods. The Necker cube (Fig. 1a) is an optical illusion first published by the Swiss crystallographer Louis Albert Necker in 1832 [1]. It provides a counter-attack against naive realism, which states that the way we observe the world is the way the world actually is. The Necker cube contradicts this claim, because we see one or the other of two cubes (Fig. 1b), but really, there is no cube there at all, but only a 2D drawing of 12 lines. We see something which is not really there, thus apparently disproving naive realism. This criticism of naive realism supports representative realism. This view argues that we experience reality indirectly by perceptions that represent the real world. For example, if we see a yellow flower, we do not actually see the flower itself but a representation of it. In this way, differences of perception which occur due to changes in the position of the viewer, light conditions, and so on can be easily explained: it is not the object that is changing, only our perception of it. Fig. 1 a The Necker cube. b Like a 2D echocardiographic image, the Necker cube may give the suggestion of a realistic representation of a 3D structure, but really there is only a 2D picture that can be interpreted in different ways Let us go back to echocardiography. Visual estimation of wall motion (‘eyeballing’) is highly subjective, imprecise and poorly reproducible. Nevertheless, some sense of naive realism seems to provide an unrealistic confidence in the accuracy of our eyes. Calculating LV volumes and EF from 2D images by using algorithms such as the biplane method of disks (modified Simpson’s rule) are considered more accurate and better reproducible. However, because of the geometric assumptions of this 2D method, measurements may be inaccurate if the shape of the left ventricle is abnormal or when the acquisition of the 2D images is suboptimal. In other words, like the yellow flower, 2D echocardiographic images are not necessarily a realistic representation of the true left ventricle, but only a perception that is influenced by subjective interpretation and variability in measurements of only a very small 2D portion of the true 3D volume.

Can visual cognitive neuroscience learn anything from the philosophy of language? Ambiguity and the topology of neural network models of multistable perception

The Necker cube and the productive class of related stimuli involving multiple depth interpretations driven by corner-like line junctions are often taken to be ambiguous. This idea is normally taken to be as little in need of defense as the claim that the Necker cube gives rise to multiple distinct percepts. In the philosophy of language, it is taken to be a substantive question whether a stimulus that affords multiple interpretations is a case of ambiguity. If we take into account what have been identified as hallmark features of ambiguity and look at the empirical record, it appears that the Necker cube and related stimuli are not ambiguous. I argue that this raises problems for extant models of multistable perception in cognitive neuroscience insofar as they are purported to apply to these stimuli. Helpfully, similar considerations also yield reasons to suggest that the relevant models are well motivated for other instances of multistable perception. However, a different breed of model seems to be required for the Necker cube and related stimuli. I end with a sketch how one may go about designing such a model relying on oscillatory patters in neural firing. I suggest that distinctions normally confined to the philosophy of language are important for the study of perception, a perspective with a growing number of adherents.

Critical slowing down and noise-induced intermittency in bistable perception: bifurcation analysis.

Stochastic dynamics and critical slowing down were studied experimentally and numerically near the onset of dynamical bistability in visual perception under the influence of noise. Exploring the Necker cube as the essential example of an ambiguous figure, and using its wire contrast as a control parameter, we measured dynamical hysteresis in two coexisting percepts as a function of both the velocity of the parameter change and the background luminance. The bifurcation analysis allowed us to estimate the level of cognitive noise inherent to brain neural cells activity, which induced intermittent switches between different perception states. The results of numerical simulations with a simple energy model are in good qualitative agreement with psychological experiments.

Cue-recruitment for extrinsic signals after training with low information stimuli.

Cue-recruitment occurs when a previously ineffective signal comes to affect the perceptual appearance of a target object, in a manner similar to the trusted cues with which the signal was put into correlation during training [1], [2]. Jain, Fuller and Backus [3] reported that extrinsic signals, those not carried by the target object itself, were not recruited even after extensive training. However, recent studies have shown that training using weakened trusted cues can facilitate recruitment of intrinsic signals [4]–[7]. The current study was designed to examine whether extrinsic signals can be recruited by putting them in correlation with weakened trusted cues. Specifically, we tested whether an extrinsic visual signal, the rotary motion direction of an annulus of random dots, and an extrinsic auditory signal, direction of an auditory pitch glide, can be recruited as cues for the rotation direction of a Necker cube. We found learning, albeit weak, for visual but not for auditory signals. These results extend the generality of the cue-recruitment phenomenon to an extrinsic signal and provide further evidence that the visual system learns to use new signals most quickly when other, long-trusted cues are unavailable or unreliable.

Eye movement-related brain activity during perceptual and cognitive processing.

Eye movement-related brain activity during perceptual and cognitive processing.

Neural processes in pseudo perceptual rivalry: An ERP and time–frequency approach

Necker cube is one of the ambiguous figures that is physically a static image but can be alternately perceived in two different perspectives. A great deal of debate exists regarding ambiguous figures that induce spontaneous switching between rival percepts. To investigate the time course of neural processes underlying such perceptual rivalry, we recorded electroencephalograms associated with participants’ perceptions of a Necker cube under ambiguous and unambiguous conditions, using a modified discontinuous-presentation method. Each condition consisted of two stimuli presented consecutively, starting with an unambiguous stimulus in both conditions. The second stimulus was either ambiguous (ambiguous condition) or unambiguous (control condition). We compared endogenous reversal activity of ambiguous stimuli with exogenous reversals. As a result, we found that the right-occipital beta-band activity (16–26Hz) increased 100–150ms and 350–450ms after the onset of the ambiguous stimulus only when the perception of the ambiguous stimulus differed from that of the first stimulus. These results indicate that activity in the right-occipital total beta band reflects endogenous switching between rivaling percepts.