In vision research metacontrast masking is a widely used technique to reduce the visibility of a stimulus. Typically, studies attempt to reveal general principles that apply to a large majority of participants and tend to omit possible individual differences. The neural plasticity of the visual system, however, entails the potential capability for individual differences in the way observers perform perceptual tasks. We report a case of perceptual learning in a metacontrast masking task that leads to the (...) enhancement of two types of adult human observers despite identical learning conditions. In a priming task both types of observers exhibited the same priming effects, which were insensitive to learning. Findings suggest that visual processing of target stimuli in the metacontrast masking task is based on neural levels with sufficient plasticity to enable the development of two types of observers, which do not contribute to processing of target stimuli in the priming task. (shrink)

In metacontrast masking target visibility is modulated by the time until a masking stimulus appears. The effect of this temporal delay differs across participants in such a way that individual human observers’ performance shows distinguishable types of masking functions which remain largely unchanged for months. Here we examined whether individual differences in masking functions depend on different response criteria in addition to differences in discrimination sensitivity. To this end we reanalyzed previously published data and conducted (...) a new experiment for further data analyses. Our analyses demonstrate that a distinction of masking functions based on the type of masking stimulus is superior to a distinction based on the target–mask congruency. Individually different masking functions are based on individual differences in discrimination sensitivities and in response criteria. Results suggest that individual differences in metacontrast masking result from individually different criterion contents. (shrink)

Relative blindsight is said to occur when different levels of subjective awareness are obtained at equality of objective performance. Using metacontrast masking, Lau and Passingham reported relative blindsight in normal observers at the shorter of two stimulus-onset asynchronies between target and mask. Experiment 1 replicated the critical asymmetry in subjective awareness at equality of objective performance. We argue that this asymmetry cannot be regarded as evidence for relative blindsight because the observers’ responses were based on different attributes of (...) the stimuli at the two SOAs. With an invariant criterion content , there was no asymmetry in subjective awareness across the two SOAs even though objective performance was the same. Experiment 3 examined the effect of criterion level on estimates of relative blindsight. Collectively, the present results question whether metacontrast masking is a suitable paradigm for establishing relative blindsight. Implications for theories of consciousness are discussed. (shrink)

In this issue of Consciousness and Cognition, Bachmann comments on our study , which revealed two groups of observers with qualitative individual differences in metacontrast masking that are enhanced by perceptual learning. We are pleased that our study receives this attention and even more about Bachmann’s extremely positive comments. In this invited reply we argue that observers seem to be similar only at the beginning of the experiment but they have no choice as to which group to join. (...) Findings strongly recommend to look at the data of individual subjects. (shrink)

There are conflicting views concerning the electrophysiological correlates of visual consciousness. Whereas one view considers a relatively late positive deflection as a primary correlate of consciousness, another model links consciousness with earlier negativity . The present experiment utilized metacontrast masking in investigating the electrophysiological correlates of visual consciousness. The participants were presented with target-mask sequences in three stimulus onset asynchronies. The target stimuli were followed by either a metacontrast mask or a similar-looking, but ineffective pseudomask. The results (...) showed that the first deflection that correlated with target visibility was VAN which was followed by LP. We argue that the VAN is the primary correlate target visibility, while the LP reflects later, postperceptual processing stages. (shrink)

While the majority of perceptual phenomena based research on consciousness is implicitly nomothetic, some idiographic perspective can be sometimes highly valuable for it. It may turn out that after having had a closer look at individual differences in the expression of psychometric functions a need to revise some nomothetic laws considered as the general ones arises as well. A study of individual differences in metacontrast masking published in this issue superbly illustrates this. A myriad of urgent research objectives (...) emerges out of this study, most of them important both for clearing up the still messy theoretical picture on visual masking and for the beginning of asking whether perceptual awareness mechanisms are so universal at all. In this commentary the problems pertinent to this issue are discussed. (shrink)

We propose a new masking technique for masking word stimuli. Drawing on the phenomena of metacontrast and paracontrast, we alternately presented two prime displays of the same word with the background color in one display matching the font color in the other display and vice versa. The sequence of twenty alterations was sandwich-masked by structure masks. Using this masking technique, we conducted evaluative priming experiments with positive and negative target and prime words. Significant priming effects were (...) found – for primes and targets drawn from the same as well as from different word sets. Priming effects were independent of prime discrimination performance in direct tests and they were still significant after the sample was restricted to those participants who showed random responding in the direct test. (shrink)

abstract Postdiction effects are phenomena in which a stimulus influences the appearance of events taking place before it. In metacontrast masking, for instance, a masking stimulus can ren- der a target stimulus shown before the mask invisible. This and other postdiction effects have been considered incompatible with a simple explanation according to which (i) our perceptual experiences are delayed for only the time it takes for a distal stimulus to reach our sensory receptors and for our neural (...) mechanisms to process it, and (ii) the order in which the processing of stimuli is completed corresponds with the apparent temporal order of stimuli. As a result, the theories that account for more than a single postdiction effect reject at least one of these theses. This paper presents a new framework for the tim- ing of experiences—the non-linear latency difference view—in which the three most dis- cussed postdiction effects—apparent motion, the flash-lag effect, and metacontrast masking—can be accounted for while simultaneously holding theses (i) and (ii). This view is grounded in the local reentrant processes, which are known to have a crucial role in perception. Accordingly, the non-linear latency difference view is both more parsimonious and more empirically plausible than the competing theories, all of which remain largely silent about the neural implementation of the mechanisms they postulate. (shrink)

Zusammenfassung Der vorliegende Beitrag analysiert die Bedeutung der Idee der umma in der „Muslimischen Jugend in Deutschland e. V.“ und der sie umgebenden pop-islamischen Szene entlang der Frage sozialer Grenzziehungsprozesse. Es soll gezeigt werden, dass soziale Grenzen nicht nur durch Zuschreibungs- und Exklusionsprozesse von außen konstruiert, sondern auch entlang von gemeinschaftsbildenden Identifikationsprozessen junger Musliminnen und Muslime hergestellt werden. Indem individuelle und kollektive Bedeutungen der Umma im Kontext des Untersuchungsfeldes erfasst werden, werden Prozesse der Vergemeinschaftung ebenso in den Blick genommen wie (...) damit verbundene soziale Distinktionen, Exklusionen und Abwertungen. Dabei zeigt sich, dass soziale Grenzziehungsprozesse der pop-islamischen Szene sowohl gegenüber der deutschen Mehrheitsgesellschaft als auch gegenüber verschiedenen islamischen Strömungen je situations- und kontextabhängig ausgehandelt werden und sich als gleichzeitige Suche nach Partizipation und Abgrenzung bzw. Inklusion und Exklusion beschreiben lassen. (shrink)

Using a metacontrast masking paradigm, prior studies have shown that a target’s color information and form information, can be processed without awareness and that unconscious color processing occurs at early, wavelength-dependent levels in the cortical information processing hierarchy. Here we used a combination of paracontrast and metacontrast masking techniques to explore unconscious color and form priming effects produced by blue, green, and neutral stimuli. We found that color priming in normal observers is significantly reduced when an (...) additional paracontrast mask precedes the target at optimal masking SOAs. However, no reduction of form-priming effects was obtained at similar optimal paracontrast SOAs. We conclude that unconscious color priming depends on an early, wavelength- or stimulus-dependent response of color neurons located at early cortical levels whereas unconscious form priming occurs at later levels. (shrink)

Dennett and Kinsbourne ([1992]) argue that metacontrast backward visual masking provides a clear illustration that ‘there is really only a verbal difference’ between two versions of the Cartesian Theater model of the mind. This alleged lack of a distinction is both the crucial premise of their main argument against the Cartesian Theater and a motivator for accepting their own Multiple Drafts model. I argue that metacontrast reveals a difference between the two versions of the Cartesian Theater that (...) meets criteria found in (Dennett and Kinsbourne [1992]) for determining such a difference. This difference undermines the soundness of their argument against the Cartesian Theater, and exerts pressure on Dennett and Kinsbourne to offer a more detailed articulation of their model. 1. Introduction2. Brief Explanation of Metacontrast Backward Visual Masking3. The Stalinesque and Orwellian Models of Metacontrast 3.1. Criteria for determining a difference4. A Difference That Makes a Difference 4.1. Skeptical hypothesis objection5. Other Objections and Replies 5.1. Straw person objection5.2. Corroborative issues objection6. Conclusion. (shrink)

Subliminal primes are assumed to produce weaker and short-lived effects on subsequent behavior compared to clearly visible primes. However, this difference in priming effect may be due to differences in signal strength, rather than level of awareness. In the present study we manipulated prime discriminability by using metacontrast masks and pseudomasks, while keeping the prime strength equal. This manipulation resulted in large differences in discriminability of the primes. However, both immediate response priming and long-term response priming was equal for (...) the poorly discriminable and well discriminable primes, and equal for groups that differed markedly in terms of how well they could discriminate the primes. Our findings imply that discriminability of information is independent of both the immediate and long-term effects that information can have on behavior. (shrink)

Subliminal primes are assumed to produce weaker and short-lived effects on subsequent behavior compared to clearly visible primes. However, this difference in priming effect may be due to differences in signal strength, rather than level of awareness. In the present study we manipulated prime discriminability by using metacontrast masks and pseudomasks, while keeping the prime strength equal. This manipulation resulted in large differences in discriminability of the primes. However, both immediate response priming and long-term response priming was equal for (...) the poorly discriminable and well discriminable primes, and equal for groups that differed markedly in terms of how well they could discriminate the primes. Our findings imply that discriminability of information is independent of both the immediate and long-term effects that information can have on behavior. (shrink)

Our visual systems account for stimulus context in brightness perception, but whether such adjustments occur for stimuli that we are unaware of has not been established. We therefore assessed whether stimulus context influences brightness processing by measuring unconscious priming with metacontrast masking. When a middle-gray disk was presented on a darker background, such that it could be consciously perceived as brighter via simultaneous brightness contrast , reaction times were significantly faster to a bright annulus than to a dark (...) annulus. We further show that context-dependent brightness priming does not correlate with visibility using an objective measure of awareness and that context-dependent, but not context-independent brightness priming, occurs equally strongly for stimuli below or above the subjective threshold for awareness . These results suggest that SBC occurs at early levels of visual input and is not influenced by conscious perception. (shrink)

In the contemporary discussions concerning unconscious perception it is not uncommon to postulate that content and phenomenal character are ‘orthogonal’, i.e., there is no type of content which is essentially conscious, but instead, every representational content can be either conscious or not. Furthermore, this is not merely treated as a thesis justified by theoretical investigations, but as supported by empirical considerations concerning the actual functioning of the human cognition. In this paper, I address unconscious color perception and argue for a (...) negative thesis—that the main experimental paradigms used in studying unconscious color perception do not provide support for the position that conscious and unconscious color representations have the same type of content. More specifically, I claim that there is no significant support for the claim that unconscious vision categorically represents surface colors. (shrink)

A modified flanker task was used to assess the effects of spatial attention during conscious and nonconscious processing. In line with prior findings, we demonstrated that increasing spatial separation between flankers and probes diminished the differences between reaction times to the incongruent and congruent probe–flanker pairs. This trend occurred even when the identity of flankers was suppressed from awareness by a metacontrast mask, indicating that spatial attention can be allocated to information processed at the nonconscious, in addition to the (...) conscious, levels, that effects of spatial attention at these two levels can be equivalent, and that attention deployed at the nonconscious level of processing can be characterized by a spatial gradient that is nearly identical to that found at the conscious level of processing. (shrink)

A recent fMRI study by Webb et al. (Cortical networks involved in visual awareness independent of visual attention, Proc Natl Acad Sci U S A 2016;113:13923–28) proposes a new method for finding the neural correlates of awareness by matching atten- tion across awareness conditions. The experimental design, however, seems at odds with known features of attention. We highlight logical and methodological points that are critical when trying to disentangle attention and awareness.

If successive, brief visual images are exposed for recognition or for psychophysical ratings, various effects and phenomena of fast dynamics of conscious perception such as mutual masking, metacontrast, proactive enhancement of contrast, proactive speed-up of the latency of subjective visual experience, the Fröhlich Effect, the Tandem Effect, attentional facilitation by visuospatial precuing, and some others have been found. The theory proposed to deal with these phenomena proceeds from the assumption that two types of brain processes are necessary in (...) order to consciously recognize visual stimuli: fast, specific processes of encoding that allocate and reactivate the stimulus representation which is based on the activity of selected cortical neurons and relatively slower processes of facilitation of the activity of this specific representation that are mediated by the excitatory modulation of the EPSPs of those selected cortical neurons by the ascending input from nonspecific thalamus. Theperceptual retouchconstruct is proposed in order to characterize and analyze the interaction of and . The neurophysiological characteristics of this bifunctional system of afference help to put forward several predictions that are found to be consistent with the empirical regularities of the above-described perceptual-attentional phenomena. These data form a body of converging evidence that is consistent with the predictions of the perceptual retouch approach. (shrink)

Any theoretician constructing a serious model of consciousness should carefully assess the details of empirical data generated in the neurosciences and psychology. A failure to account for those details may cast doubt on the adequacy of that model. This paper presents a case in point. Dennett and Kinsbourne's (Dennett, D., & Kinsbourne, M. (1992). Time and the observer: The where and when of consciousness in the brain. Behavioral and Brain Sciences, 15, 183-243) assault on the materialist version of the Cartesian (...) Theater model of the mind relies significantly on the superiority of their Multiple Drafts model of consciousness as an explanation of the phenomenon of metacontrast. However, their description of metacontrast is, in important ways, inadequate. The result is that their explanation of how the Multiple Drafts model handles this phenomenon fails to account for the actual data. In this paper I offer a more complete description of metacontrast, show how Dennett and Kinsbourne's explanation fails, and argue that there are good theoretical reasons for choosing the so-called Stalinesque model over the so-called Orwellian model. (shrink)

The author takes the contemporary theatre performance of Mátohy [The Spooks] and maps out the use of original folk theatre masks in a new theatrical context. He describes and characterizes the changes that occur as a consequence of transposing folk masks from their traditional environment to the contemporary stage.

During emerging public health crises, both policymakers and members of the public are looking to scientific experts to provide guidance. Even in cases where there are significant uncertainties, there is pressure for experts to “speak with one voice” to avoid confusion, allow officials to make evidence-based decisions rapidly, and encourage public support for such decisions. This can lead experts to engage in masking of information about the state of the science or regarding assumptions involved in policy recommendations. Although experts (...) might have good reasons for masking disagreements, uncertainties, or assumptions when offering policy advice, we argue that this strategy can result in epistemic harms. Using the case of the COVID-19 pandemic, we show that public health authorities masked two types of information necessary for laypersons to evaluate public health recommendations: (1) experts’ disagreements about the scientific evidence and (2) the role of values in making inferences from the science to policy positions. We contend that this resulted in epistemic harms against laypeople that provide a pro tanto case against masking information. We further argue that when the science is in flux and policies need to be implemented despite significant uncertainties, there is an all-things-considered case against masking the types of information discussed. (shrink)

Our visual system can process information at both conscious and unconscious levels. Understanding the factors that control whether a stimulus reaches our awareness, and the fate of those stimuli that remain at an unconscious level, are the major challenges of brain science in the new millennium. Since its publication in 1984, Visual Masking has established itself as a classic text in the field of cognitive psychology. In the years since, there have been considerable advances in the cognitive neurosciences, and (...) a growth of interest in the topic of consciousness, and the time is ripe for a new edition of this text. Where most current approaches to the study of visual consciousness adopt a 'steady-state' view, the approach presented in this book explores its dynamic properties. This new edition uses the technique of visual masking to explore temporal aspects of conscious and unconscious processes down to a resolution in the millisecond range. The 'time slices' through conscious and unconscious vision revealed by the visual masking technique can shed light on both normal and abnormal operations in the brain. The main focus of this book is on the microgenesis of visual form and pattern perception - microgenesis referring to the processes occurring in the visual system from the time of stimulus presentation on the retinae to the time, a few hundred milliseconds later, of its registration at conscious or unconscious perceptual and behavioural levels. The book takes a highly integrative approach by presenting microgenesis within a broad context encompassing visuo-temporal phenomena, attention, and consciousness. (shrink)

This new edition uses the technique of visual masking to explore temporal aspects of conscious and unconscious processes down to a resolution in the...

There are many reasons why scientific experts may mask disagreement and endorse a position publicly as “jointly accepted.” In this paper I consider the inner workings of a group of scientists charged with deciding not only a technically difficult issue, but also a matter of social and political importance: the maximum acceptable dose of radiation. I focus on how, in this real world situation, concerns with credibility, authority, and expertise shaped the process by which this group negotiated the competing virtues (...) of reaching consensus versus reporting accurately the nature and degree of disagreement among them. (shrink)

Masks, interferers, finks, reverse finks, and mimickers are troublesome for powers metaphysics insofar as the latter concedes that there are powers with essential stimuli/activation conditions. In this article, I aim at offering a novel approach for solving this problem. In Section 1, I shall present the problem; and in Section 2, I shall briefly show how it also arises within non‐reductive views of powers. Subsequently, in Section 3, I shall examine the failure of the ceteris paribus solution. The pars construens (...) will begin in Section 4, where I shall distinguish between the activation conditions, the background conditions, and the possession conditions of a power. Within each category, I shall draw further distinctions. In Section 5, I shall demonstrate how such distinctions may ground a solution to our problem. Finally, in Section 6, I shall anticipate and reply to four objections. (shrink)

There are many reasons why scientific experts may mask disagreement and endorse a position publicly as “jointly accepted.” In this paper I consider the inner workings of a group of scientists charged with deciding not only a technically difficult issue, but also a matter of social and political importance: the maximum acceptable dose of radiation. I focus on how, in this real world situation, concerns with credibility, authority, and expertise shaped the process by which this group negotiated the competing virtues (...) of reaching consensus versus reporting accurately the nature and degree of disagreement among them. (shrink)

An object's disposition to A in circumstances C is masked if circumstances C obtain without the object Aing. This paper explores an analogous sense in which abilities can be masked, and it uses the results of this exploration to motivate an analysis of agents' abilities in terms of dispositions. This analysis is then shown to provide the resources to defend a version of the Principle of Alternate Possibilities against Frankfurt-style counterexamples. Although this principle is often taken to be congenial to (...) incompatibilism concerning free action and determinism, the paper concludes by using the dispositional analysis of abilities to argue for compatibilism, and to show why the 'master argument' for incompatibilism is unsound. (shrink)