Subliminal perception (SP) is today considered a well-supported theory stating that perception can occur without conscious awareness and have a significant impact on later behaviour and thought. In this article, we first present and discuss different approaches to the study of SP. In doing this, we claim that most approaches are based on a dichotomic measure of awareness. Drawing upon recent advances and discussions in the study of introspection and phenomenological psychology, we argue for both the possibility and (...) necessity of using an elaborated measure of subjective states. In the second part of the article, we present findings where these considerations are implemented in an empirical study. The results and implications are discussed in detail, both with reference to SP, and in relation to the more general problem of using elaborate introspective reports as data in relation to studies of cognition. (shrink)
Unconscious processes, by whatever name they may be known , are invariably operationalized by the dissociation paradigm, any situation involving the dissociation between two indicators , one of availability and the other, of accessibility , such that, ε>α. Subliminal perception has been traditionally defined by a special case of the dissociation paradigm in which availability exceeds accessibility when accessibility is null . Construct validity issues bedevil all dissociation paradigms since it is not clear what might constitute appropriate indicators that, (...) moreover, are pure and exhaustive. Semantic and theoretic drifts in the recent literature—e.g., the confusion of different versions of the dissociation paradigm, the equation of conscious–unconscious with direct–indirect tests, and the foisting of the criterion of qualitative differences—have tended to undermine emerging theoretic parsimony. On the other hand, a crucial factor has been left out of theory development: time. Both ε and α can rise and fall over time, often asynchronously, and so dissociations may wax and wane and, even, reverse over time. Some laboratory evidence suggests that accessibility measures , as they approach chance, may actually dip below chance . If so, d′=0 , could be an averaging artifact of positive and negative d′s. Conscious accessibility is not either–or but more or less, and variable over time. (shrink)
We addressed the questions whether stimuli presented below the threshold of verbal awareness are nevertheless perceived and whether there are perceptual differences between the two cerebral hemispheres. Pictures of line drawn objects and animals were subliminally presented to each visual half-field for subsequent identification in a form as fragmented as possible. The performance of 40 healthy subjects was compared to that of 63 controls. Whereas identification performance after blank presentation in the experimental group did not differ from that of controls, (...) identification in a significantly more fragmented form was achieved after the presentation of the complete picture. This effect, however, occurred only after subliminal stimulation in the left visual field, i.e., of the right hemisphere. Our results show that pictures presented below the threshold of verbal awareness can be perceived, and that only the right hemisphere can perceive them and make use of the perception. It remains an open question whether this kind of hemispheric specialization represents a right hemisphere dominance for subliminal perception or reflects an inability of the left hemisphere to access and behaviorally use unaware percepts via fragmented picture identification, for which a right hemisphere advantage is known. (shrink)
Amidst the many brain events evoked by a visual stimulus, which are specifically associated with conscious perception, and which merely reflect non-conscious processing? Several recent neuroimaging studies have contrasted conscious and non-conscious visual processing, but their results appear inconsistent. Some support a correlation of conscious perception with early occipital events, others with late parieto-frontal activity. Here we attempt to make sense of those dissenting results. On the basis of a minimal neuro-computational model, the global neuronal workspace hypothesis, we (...) propose a taxonomy which distinguishes between vigilance and access to conscious report, as well as between subliminal, preconscious and conscious processing. We suggest that these distinctions map onto different neural mechanisms, and that conscious perception is systematically associated with a sudden surge of parieto-frontal activity causing top-down amplification. (shrink)
Previous studies making use of indirect processing measures have shown that perceptual grouping can occur outside the focus of attention. However, no previous study has examined the possibility of subliminal processing of perceptual grouping. The present work steps forward in the study of perceptual organization, reporting direct evidence of subliminal processing of Gestalt patterns. In two masked priming experiments, Gestalt patterns grouped by proximity or similarity that induced either a horizontal or vertical global orientation of the stimuli were presented as (...) masked primes and followed by visible targets that could be congruent or incongruent with the orientation of the primes. The results showed a reliable priming effect in the complete absence of prime awareness for both proximity and similarity grouping principles. These findings suggest that a phenomenal report of the Gestalt pattern is not mandatory to observe an effect on the response based on the global properties of Gestalt stimuli. (shrink)
Research has shown repeatedly that attention influences implicit learning effects. In a similar vein, interoceptive awareness might be involved in unaware fear conditioning: The fact that the CS is repeatedly presented in the context of aversive bodily experiences might facilitate the development of conditioned responding. We investigated the role of interoceptive attention in a subliminal conditioning paradigm. Conditioning was embedded in a spatial cueing task with subliminally presented cues that were followed by a masking stimulus. Response times to the targets (...) that were either validly or invalidly predicted by the cues served as index of conditioning. Interoceptive attention was manipulated between-subjects. Half the participants completed a heartbeat detection task before conditioning. This task tunes attention to one’s own bodily signals. We found that conditioned responding was facilitated in this latter group of participants. These results are in line with the hypothesis that a rise interoceptive attention enhances unaware conditioned responding. (shrink)
Eighty-four undergraduate male subjects were tachistoscopically exposed either to an experimental message designed to arouse anxiety , or to a neutral control message , at 4 ms or 200 ms durations. Electrodermal responses were recorded before, during and after exposure to the critical messages. Three measures of awareness of 4 ms stimuli were used; recall, recognition and discrimination. No evidence of stimulus awareness was found on any of these measures. Only subjects exposed to the experimental message at 4 ms durations (...) showed a significant increase in EDR from pre-exposure to message exposure period. These results support Silverman's hypothesis that drive-related stimuli must be presented subliminally in order to produce significant effects on behavior, and are consistent with Bornstein's hypothesis that stimulus awareness inhibits responding to drive- and affect-related stimuli. (shrink)
“Source monitoring” theory is applied to the turn-of-the-century argument that, whenever binocularly fused patterns are self-consciously apperceived, both eyes' monocular sensations are consciously perceived. According to monitoring theory's refinement of the argument, binocularly apperceived patterns are accompanied by selfconsciousness that one is perceiving patterns , whereas monocular sensations are accompanied by no self-consciousness of their source. In the current test of this refined argument, 32 subjects were monocularly presented with 6 letters of the alphabet, while binocularly fusing 6 different letters, (...) and were subsequently required to discriminate these 12 letters from 6 other letters that they had visually imaged. Consistent with monitoring theory, the results of experimental testing suggest that binocularly fused letters are neurally monitored as “peripheral,” self-consciously experienced as “perceived,” and subsequently remembered as not “imaged.” The results further suggest that, during such binocular apperception, monocular data are not totally unconscious-like computer data-but are consciously experienced as “sourceless” sensations that are memorially confused with visually imaged sensations. (shrink)
When the stored representation of the meaning of a stimulus is accessed through the processing of a sensory input it is maintained in an activated state for a certain amount of time that allows for further processing. This semantic activation is generally accompanied by conscious identification, which can be demonstrated by the ability of a person to perform discriminations on the basis of the meaning of the stimulus. The idea that a sensory input can give rise to semantic activation without (...) concomitant conscious identification was the central thesis of the controversial research in subliminal perception. Recently, new claims for the existence of such phenomena have arisen from studies in dichotic listening, parafoveal vision, and visual pattern masking. Because of the fundamental role played by these types of experiments in cognitive psychology, the new assertions have raised widespread interest. (shrink)
In a recent article, [Sergent, C. & Dehaene, S. . Is consciousness a gradual phenomenon? Evidence for an all-or-none bifurcation during the attentional blink, Psychological Science, 15, 720–729] claim to give experimental support to the thesis that there is a clear transition between conscious and unconscious perception. This idea is opposed to theoretical arguments that we should think of conscious perception as a continuum of clarity, with e.g., fringe conscious states [Mangan, B. . Sensation’s ghost—the non-sensory “fringe” of (...) consciousness, Psyche, 7, 18]. In the experimental study described in this article, we find support for this opposite notion that we should have a parsimonious account of conscious perception. Our reported finding relates to the hypothesis that there is more than one perceptual threshold [Merikle, P.M., Smilek, D. & Eastwood, J.D. . Perception without awareness: perspectives from cognitive psychology, Cognition, 79, 115–134], but goes further to argue that there are different “levels” of conscious perception. (shrink)
Erdelyi does us all a great service by his customarily incisive discussion of the various ways in which our field tends to neglect, confuse, and misunderstand numerous critical issues in attempting to differentiate conscious from unconscious perception and memory. Although no single commentary could hope to comprehensively assess these issues, I will address Erdelyi’s three main points: How the dissociation paradigm can be used to validly infer unconscious perception; The implications of below-chance effects; and The role of time. (...) I suggest that significant progress on construct validity issues is possible; below-chance effects are part of a more general bidirectional phenomenon, very likely unconscious, and do not threaten absolute subliminality; and practice/learning effects pose potential difficulties for time-based dissociation paradigms. (shrink)
This article reports four subliminal perception experiments using the relationship between confidence and accuracy to assess awareness. Subjects discriminated among stimuli and indicated their confidence in each discrimination response. Subjects were classified as being aware of the stimuli if their confidence judgments predicted accuracy and as being unaware if they did not. In the first experiment, confidence predicted accuracy even at stimulus durations so brief that subjects claimed to be performing at chance. This finding indicates that subjects's claims that (...) they are ''just guessing'' should not be accepted as sufficient evidence that they are completely unaware of the stimuli. Experiments 2-4 tested directly for subliminal perception by comparing the minimum exposure duration needed for better than chance discrimination performance against the minimum needed for confidence to predict accuracy. The latter durations were slightly but significantly longer, suggesting that under certain circumstances people can make perceptual discriminations even though the information that was used to make those discriminations is not consciously available. (shrink)
In their comment on Sandberg, Timmermans, Overgaard, and Cleeremans , Dienes and Seth argue that increased sensitivity of the Perceptual Awareness Scale is a consequence of the scale being less exclusive rather than more exhaustive. According to Dienes and Seth, this is because PAS may measure some conscious content, though not necessarily relevant conscious content, “If one saw a square but was only aware of seeing a flash of something, then one has not consciously seen a square.” In this reply, (...) we claim that there is a difference between conscious visual experience, which may be partial, and the resulting conscious content, which is conceptual. Whereas PAS measures the first, confidence judgments and post-decision wagering measure the second. (shrink)
Reingold and MerikleÕs (1988, 1990) critique of the classic dissociation paradigm identiﬁed several issues as inherent problems that severely undermine the utility of this paradigm. Erdelyi (2004) extending his prior analysis (Erdelyi, 1985, 1986) points out several additional factors that may complicate the interpretation of empirically obtained dissociations. The goal of the present manuscript is to further discuss some of these commonly neglected interpretive diﬃculties. Ó 2003 Elsevier Inc. All rights reserved.
We argue that the effects of evaluative learning may occur (a) without conscious perception of the affective stimuli, (b) without awareness of the stimulus contingencies, and (c) without any awareness that learning has occurred at all. Whether the three experiments reported in our target article provide conclusive evidence for either or any of these assertions is discussed in the commentaries of De Houwer and Field. We respond with the argument that when considered alongside other studies carried out over the (...) past few decades, our experiments provide compelling evidence for a theory that posits a dissociation between evaluative learning and contingency awareness. (shrink)
Dienes and Seth (2010) conclude that confidence ratings and post-decision wagering are two comparable and recommendable measures of conscious experience. In a recently submitted paper, we have however found that both methods are problematic and seem less suited to measure consciousness than a direct introspective measure. Here, we discuss the methodology and conclusions put forward by Dienes and Seth, and why we think the two experiments end up with so different recommendations.