Emotional processing without conscious awareness plays an important role in human social interaction. Several behavioral studies reported that subliminal presentation of photographs of emotional facial expressions induces unconscious emotional processing. However, it was difficult to elicit strong and robust effects using this method. We hypothesized that dynamic presentations of facial expressions would enhance subliminal emotional effects and tested this hypothesis with two experiments. Fearful or happy facial expressions were presented dynamically or statically in either the left or the right visual (...) field for 20 (Experiment 1) and 30 (Experiment 2) ms. Nonsense target ideographs were then presented, and participants reported their preference for them. The results consistently showed that dynamic presentations of emotional facial expressions induced more evident emotional biases toward subsequent targets than did static ones. These results indicate that dynamic presentations of emotional facial expressions induce more evident unconscious emotional processing. (shrink)

Research on perception without awareness has provoked strong emotional responses from individuals within and outside the scientific community, due in part to the perceived potential for abuse of subliminal techniques. In this paper, four basic issues regarding the use of subliminal techniques for propaganda purposes are discussed: whether exposure to subliminal stimuli can produce significant, predictable changes in affect, cognition and behavior; whether these effects are robust and powerful enough to make the use of subliminal techniques for propaganda purposes feasible; (...) whether the effects of subliminal stimulation are stable over time; and whether subliminal influences can be resisted by unwilling subjects. Research suggests that exposure to simple drive-or affect-related subliminal stimuli can produce ecologically significant, temporally stable changes in attitudes and behavior, and therefore may have potential for use as propaganda tools. Implications of these findings for our understanding of the mechanisms underlying subliminal perception are discussed. Technical problems which would need to be addressed before subliminal propaganda techniques could be employed are also discussed. Ethical issues raised by the use of covert attitude and behavior manipulation techniques are addressed. (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)

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)

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)

Electroencephalogram has been widely utilized in emotion recognition. Psychologists have found that emotions can be divided into conscious emotion and unconscious emotion. In this article, we explore to classify subliminal emotions with EEG signals elicited by subliminal face stimulation, that is to select appropriate features to classify subliminal emotions. First, multi-scale sample entropy, wavelet packet energy, and wavelet packet entropy of EEG signals are extracted. Then, these features are fed into the decision tree and improved random forest, respectively. The (...) classification accuracy with Ei and WpEn is higher than MSpEn, which shows that Ei and WpEn can be used as effective features to classify subliminal emotions. We compared the classification results of different features combined with the decision tree algorithm and the improved random forest algorithm. The experimental results indicate that the improved random forest algorithm attains the best classification accuracy for subliminal emotions. Finally, subliminal emotions and physiological proof of subliminal affective priming effect are discussed. (shrink)

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 as larger (...) than 55, the novel masked prime 37 paradoxically facilitated the “larger” response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory. (shrink)

Rapid advances in the field of neuroimaging techniques including magnetoencephalography (MEG), electroencephalography (EEG), functional MRI (fMRI), diffusion tensor imaging (DTI), voxel based morphomentry (VBM), and optical imaging, have allowed neuroscientists to investigate neural processes in ways that have not been possible until recently. Combining these techniques with advanced analysis procedures during different conditions such as hypnosis, psychiatric and neurological conditions, subliminal stimulation, and psychotropic drugs began transforming the study of neuroscience, ushering a new paradigm that may allow neuroscientists to (...) tackle the hard problem of consciousness. (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.

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)

Awareness is a personal experience, which is only accessible to the rest of world through interpretation. We set out to identify a neural correlate of visual awareness, using brief subliminal and supraliminal verbal stimuli while measuring cerebral blood flow distribution with H215O PET. Awareness of visual verbal stimuli differentially activated medial parietal association cortex (precuneus), which is a polymodal sensory cortex, and dorsolateral prefrontal cortex, which is thought to be primarily executive. Our results suggest participation of these higher order perceptual (...) and executive cortical structures in visual verbal awareness. (shrink)

The "relational mind" approach to the inner content of consciousness is developed in terms of various control structures and processing strategies and their possible neurobiological identifications in brain sites. This leads naturally to a division of consciousness into a passive and an active part. A global control structure for the "single strand" aspect of consciousness is proposed as the thalamo-nucleus reticularis thalami-cortex coupled system, which is related to experimental data on the electrical stimulation of awareness. Local control, in terms (...) of excitatory transfer from pre-processing sites to posterior working memory regions, is supported by data on subliminal perception timing and disambiguation of poorly defined percepts. The inner content of consciousness is understood as arising from the resulting relational features between inputs and stored pre-processing and episodic memories. Strong analogies are drawn between emergent properties of the model and suggested properties of "raw feels", supporting the thesis that working memories are the initial sites for the emergence of phenomenal awareness, and the frontal lobes for its further adumbration in terms of higher cognitive processing, including the creation of self. (shrink)

The present paper is a kind of selective summary of my book The Genesis of Yogācāra-Vijñānavāda. [1.–2.] It deals with questions of origin and early development of three basic concepts of this school, viz., the ‘idealist’ thesis that the whole world is mind only or manifestation only, the assumption of a subliminal layer of the mind, and the analysis of phenomena in terms of the “Three Natures”. [3.] It has been asserted that these three basic concepts are logically inseparable and (...) therefore must have been introduced conjointly. [4.] Still, from Vasubandhu onward treatises have been written in which only one of the three concepts is advocated or demonstrated to be indispensable, without any reference to the other two being made. Likewise, in most of the earlier Yogācāra treatises, the three concepts occur in different sections or contexts, or are even entirely absent, as vijñaptimātra in the Yogācārabhūmi and ālayavijñāna in the Mahāyānasūtrālaṁkāra and Madhyāntavibhāga. [5.] It is therefore probable that the three concepts were introduced separately and for different reasons. [5.1.] As regards the concept of the “Three Natures”, I very hypothetically suggest that it was stimulated by the Tattvārthapaṭala of the Bodhisatvabhūmi. [5.2.1.] In the case of ālayavijñāna, I still think that my hypothesis that the concept originated from a problem emerging in connection with the “attainment of cessation” holds good and has not been conclusively refuted, but I admit that Prof. Yamabe?s hypothesis is a serious alternative. [5.2.2.] An important point is that in the Yogācārabhūmi we come across two fundamentally different concepts of ālayavijñāna, the starting point for the change being, probably, the fifth chapter of the Saṁdhinirmocanasūtra. [5.3.] As for ‘idealism’, we may have to distinguish two strands, which, however, tend to merge. [5.3.1.] The earlier one uses the concept cittamātra and emerges as early as in the Pratyutpanna-buddha-saṁmukhāvasthita-samādhi-sūtra in connection with an interpretation of visions of the Buddha Amitāyus. [5.3.2.] The later strand introduces the concept vijñaptimātra and seems to have originated in the eighth chapter of the Saṁdhinirmocanasūtra in connection with a reflection on the images perceived in insight meditation. [5.3.3.] In texts like the Mahāyānasūtrālaṁkāra, concepts from other Mahāyānasūtra strands become prominent in this connection, and it is only in the Mahāyānasaṁgraha that the use of vijñaptimātra is finally established. (shrink)

The contribution of action-perception systems of the brain to lexical semantics remains controversial. Here, we used high-definition transcranial direct current stimulation (HD-tDCS) in healthy adults to examine the role of primary (left hand motor area; HMA) and higher-order (left anterior inferior parietal lobe; aIPL) action areas in action-related word processing (action verbs and manipulable nouns) compared to non-action-related control words (non-action verbs and non-manipulable nouns). We investigated stimulation-related effects at three levels of semantic processing: subliminal, implicit, and explicit. (...) Broadly, we found that stimulation of HMA and aIPL resulted in relative facilitation of action-related language processing compared to non-action. HMA stimulation facilitated action verb processing in subliminal and implicit task contexts, suggesting that HMA helps represent action verbs even in semantically shallow tasks. HMA stimulation also facilitated manipulable noun comprehension in an explicit semantic task, suggesting that HMA contributes to manipulable noun comprehension when semantic demands are high. aIPL stimulation facilitated both manipulable noun and action verb processing during an implicit task. We suggest that both HMA and aIPL play a functional role in action semantics. HMA plays a general role in the semantics of actions and manipulable objects, while aIPL is important only when visuo-motor coordination is required for the action. (shrink)

Attentional scanning was studied in anxious and non-anxious participants, using a modified change detection paradigm. Participants detected changes in pairs of emotional scenes separated by two task irrelevant slides, which contained an emotionally valenced scene and a visual mask. In agreement with attentional control theory, change detection latencies were slower overall for anxious participants. Change detection in anxious, but not non-anxious, participants was influenced by the emotional valence and exposure duration of distractor scenes. When negative distractor scenes were presented at (...) subliminal exposure durations, anxious participants detected changes more rapidly than when supraliminal negative scenes or subliminal positive scenes were presented. We propose that for anxious participants, subliminal presentation of emotionally negative distractor scenes stimulated attention into a dynamic state in the absence of attentional engagement. Presentation of the same scenes at longer exposure times was accompanied by conscious awareness, attentional engagement, and slower change detection. (shrink)

Our approach is based on a tri-partite method of integrating psychodynamic hypotheses, cognitive subliminal processes, and psychophysiological alpha power measures. We present ten social phobic subjects with three individually selected groups of words representing unconscious conflict, conscious symptom experience, and Osgood Semantic negative valence words used as a control word group. The unconscious conflict and conscious symptom words, presented subliminally and supraliminally, act as primes preceding the conscious symptom and control words presented as supraliminal targets. With alpha power as a (...) marker of inhibitory brain activity, we show that unconscious conflict primes, only when presented subliminally, have a unique inhibitory effect on conscious symptom targets. This effect is absent when the unconscious conflict primes are presented supraliminally, or when the target is the control words. Unconscious conflict prime effects were found to correlate with a measure of repressiveness in a similar previous study (Shevrin et al., 1992, 1996). Conscious symptom primes have no inhibitory effect when presented subliminally. Inhibitory effects with conscious symptom primes are present, but only when the primes are supraliminal, and they did not correlate with repressiveness in a previous study (Shevrin et al., 1992, 1996). We conclude that while the inhibition following supraliminal conscious symptom primes is due to conscious threat bias, the inhibition following subliminal unconscious conflict primes provides a neurological blueprint for dynamic repression: it is only activated subliminally by an individual's unconscious conflict and has an inhibitory effect specific only to the conscious symptom. These novel findings constitute neuroscientific evidence for the psychoanalytic concepts of unconscious conflict and repression, while extending neuroscience theory and methods into the realm of personal, psychological meaning. (shrink)

The present study used masked repetition priming to examine whether face representations can be accessed without attention. Two experiments using a face recognition task presented masked repetition and control primes in spatially unattended locations prior to target onset. Experiment 1 used the same images as primes and as targets and Experiment 2 used different images of the same individual as primes and targets. Repetition priming was observed across both experiments regardless of whether spatial attention was cued to the location of (...) the prime. Priming occurred for both famous and non-famous targets in Experiment 1 but was only reliable for famous targets in Experiment 2, suggesting that priming in Experiment 1 indexed access to view-specific representations whereas priming in Experiment 2 indexed access to view-invariant, abstract representations. Overall, the results indicate that subliminal access to abstract face representations does not rely on attention. (shrink)

Graham Bird; XIV*—Subliminal Perception, Proceedings of the Aristotelian Society, Volume 73, Issue 1, 1 June 1973, Pages 217–232, https://doi.org/10.1093/aristo.

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)

Open peer commentary on the article “The Uroboros of Consciousness: Between the Naturalisation of Phenomenology and the Phenomenologisation of Nature” by Sebastjan Vörös. Upshot: I present a concrete example of how phenomenology might “seriously” contribute to our understanding of certain aspects of the human mind, by drawing on recent research in psychopathology.