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)

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)

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)

A series of five experiments investigated the extent of subliminal processing of negation. Participants were presented with a subliminal instruction to either pick or not pick an accompanying noun, followed by a choice of two nouns. By employing subjective measures to determine individual thresholds of subliminal priming, the results of these studies indicated that participants were able to identify the correct noun of the pair – even when the correct noun was specified by negation. Furthermore, using a (...) grey-scale contrast method of masking, Experiment 5 confirmed that these priming effects were evidenced in the absence of partial awareness, and without the effect being attributed to the retrieval of stimulus–response links established during conscious rehearsal. (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)

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)

Prefrontal cortex is dysregulated in women with restricting anorexia nervosa . It is not known whether appetitive non-conscious stimuli bias cognitive responses in those with RAN. Thirteen women with RAN and 20 healthy controls completed a dorsolateral PFC working memory task and an anterior cingulate cortex conflict task, while masked subliminal food, aversive and neutral images were presented. During the DLPFC task, accuracy was higher in the RAN compared to the HC group, but superior performance was compromised when (...) class='Hi'>subliminal food stimuli were presented: errors positively correlated with self-reported trait anxiety in the RAN group. These effects were not observed in the ACC task. Appetitive activation is intact and anxiogenic in women with RAN, and non-consciously interacts with working memory processes associated with the DLPFC. This interaction mechanism may underlie cognitive inhibition of appetitive processes that are anxiety inducing, in people with AN. (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)

According to the spreading hypothesis of object-based attention, a subliminal cue that can successfully capture attention to a location within an object should also cause attention to spread throughout the whole cued object and lead to the same-object advantage. Instead, we propose that a subliminal cue favors shifts of attention between objects and strengthens the between-object link, which is coded primarily within the dorsal pathway that governs the visual guidance of action. By adopting the two-rectangle method and using (...) an effective subliminal cue to compare with the classic suprathreshold cue, we found a different result pattern with suprathreshold cues than with subliminal cues. The suprathreshold cue replicated the conventional location and object effects, whereas a subliminal cue led to a different-object advantage with a facilitatory location effect and a same-object advantage with an inhibitory location effect. These results support our consciousness-dependent shifting hypothesis but not the spreading hypothesis. (shrink)

In a task requiring speeded bidirectional responses to arrow symbols , “free choice” responses to interspersed bidirectional stimuli are influenced by masked directional primes . By varying stimulus–response compatibility, we tested whether this priming effect is mediated by the conscious instructional set, or instead by pre-existing directional associations to the symbols. In two experiments, one group of participants was instructed to respond with the hand consistent with the implied direction of the arrow symbols, while another group was instructed to make (...) the spatially opposite responses. Both groups showed priming of “free choice” responses. However, such priming was always biased according to the instructional set rather than pre-existing associations. Subliminal priming of “free choice” responses therefore depends on conscious task goals. (shrink)

In two experiments, we tested whether fearful facial expressions capture attention in an awareness-independent fashion. In Experiment 1, participants searched for a visible neutral face presented at one of two positions. Prior to the target, a backward-masked and, thus, invisible emotional or neutral face was presented as a cue, either at target position or away from the target position. If negative emotional faces capture attention in a stimulus-driven way, we would have expected a cueing effect: better performance where fearful or (...) disgusted facial cues were presented at target position than away from the target. However, no evidence of capture of attention was found, neither in behavior, nor in event-related lateralizations. In Experiment 2, we went one step further and used fearful faces as visible targets, too. Thereby, we sought to boost awareness-independent capture of attention by fearful faces. However, still, we found no significant attention-capture effect. Our results show that fearful facial expressions do not capture attention in an awareness-independent way. Results are discussed in light of existing theories. (shrink)

ABSTRACTAnother individual’s gaze automatically shifts an observer’s attention to a location. This reflexive response occurs even when the gaze is presented subliminally over a short period. Another’s gaze also increases the preference level for items in the gaze direction; however, it was previously unclear if this effect occurs when the gaze is presented subliminally. This study showed that the preference levels for nonsense figures looked at by a subliminal gaze were significantly greater than those for items that were subliminally (...) looked away from. Targets that were looked at by a subliminal gaze were detected faster ; however, the participants were unable to detect the gaze direction. These results indicate that another individual’s gaze automatically increases the preference levels for items in the gaze direction without conscious awareness. (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.

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.

In his analysis of subliminal perception research, Erdelyi documented two important phenomena: subchance perception and temporal variability in stimulus availability and accessibility. This Commentary addresses three issues raised by Erdelyi's review: the importance of distinguishing “micro” from “macro” temporal shifts; the need to analyze perception without awareness data at the level of the individual as well as the group; and parallels between the dissociations associated with neuroclinical phenomena and those observed in patients with certain forms of personality pathology. Continued (...) integration of laboratory findings with in vivo observations of clinical syndromes will yield a more cohesive and heuristic approach to the study of implicit mental states. (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)

Concerns about threats to human autonomy feature prominently in the field of AI ethics. One aspect of this concern relates to the use of AI systems for problematically manipulative influence. In response to this, the European Union’s draft AI Act (AIA) includes a prohibition on AI systems deploying subliminal techniques that alter people’s behavior in ways that are reasonably likely to cause harm (Article 5(1)(a)). Critics have argued that the term ‘subliminal techniques’ is too narrow to capture the (...) target cases of AI-based manipulation. We propose a definition of ‘subliminal techniques’ that (a) is grounded on a plausible interpretation of the legal text; (b) addresses all or most of the underlying ethical concerns motivating the prohibition; (c) is defensible from a scientific and philosophical perspective; and (d) does not over-reach in ways that impose excessive administrative and regulatory burdens. The definition is meant to provide guidance for design teams seeking to pursue responsible and ethically aligned AI innovation. (shrink)

Los estudios recientes sobre Hobbes han puesto una gran atención en el uso de las imágenes. Permanece, sin embargo, una objeción seria y factible: se podría argumentar que Hobbes no relaciona su producción de imágenes, ni a su política, ni a su teoría de la percepción y que, por tanto, no tenemos razón para creer que sus imágenes son una aplicación de esta doctrina. El propósito de este trabajo es mostrar que Hobbes de hecho sí vincula — de un modo (...) implícito — la construcción de imágenes y su teoría psicológica al orden político. Primero, el artículo reconstruye la teoría hobbesiana de la percepción y sus implicaciones. Segundo, se muestra que el Leviathan establece encubiertamente el vínculo entre la teoría de las imágenes y las imágenes políticas, incluyendo, por consiguiente, las creadas por el propio Hobbes. Tercero, se muestra que el Leviatán de Hobbes rara vez descubre su rol como dispositivo para ver, para hacer que el lector vea imágenes que él considera necesarias. Finalmente, se discuten las consecuencias de este descubrimiento para nuestra comprensión de Hobbes y de la visualidad y las imágenes en el pensamiento político. (shrink)

An important approach to understand how the brain gives rise to consciousness is to probe the depth of unconscious processing, thus to define the key features that cause conscious awareness. Here, we investigate the possibility for subliminal stimuli to shape the context for unconscious processing. Context effects have generally been assumed to require consciousness. In the present experiment, unconscious context processing was investigated by looking at the impact of the context on the response activation elicited by a subliminal (...) prime. We compared the effects of the same subliminal prime on target processing when the prime was embedded in different unconscious contexts. Results showed that the same prime can evoke opposite responses depending on the unconscious context in which it is presented. Taken together, the results of this study show that context effects can be unconscious. (shrink)