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Detecting faces and identifying their emotional expressions are essential for social interaction. The importance of expressions has prompted suggestions that some emotionally-relevant facial features may be processed unconsciously, and it has been further suggested that this unconscious processing yields preferential access to awareness. Evidence for such preferential access has predominantly come from reaction times in the Breaking Continuous Flash Suppression (b-CFS) paradigm, which measures how long it takes different stimuli to overcome interocular suppression. For instance, it has been claimed that fearful expressions break through suppression faster than neutral expressions. However, in the b-CFS procedure, observers can decide how much information they receive before committing to a report, so although their responses may reflect differential detection sensitivity, they may also be influenced by differences in decision criteria, stimulus identification, and response production processes. Here, we employ a procedure that directly measures sensitivity for both face detection and identification of facial expressions, using predefined exposure durations. We apply diverse psychophysical approaches – forced-choice localisation, presence/absence detection, and staircase-based threshold measurement; across six experiments, we find that emotional expressions do not alter detection sensitivity to faces as they break through CFS. Our findings constrain the possible mechanisms underlying previous findings: faster reporting of emotional expressions’ breakthrough into awareness is unlikely to be due to the presence of emotion affecting perceptual sensitivity; the source of such effects is likely to reside in one of the many other processes that influence response times.

The theory of universal emotions suggests that certain emotions such as fear, anger, disgust, sadness, surprise and happiness can be encountered cross-culturally. These emotions are expressed using specific facial movements that enable human communication. More recently, theoretical and empirical models have been used to propose that universal emotions could be expressed via discretely different facial movements in different cultures due to the non-convergent social evolution that takes place in different geographical areas. This has prompted the consideration that own-culture emotional faces have distinct evolutionary important sociobiological value and can be processed automatically, and without conscious awareness. In this paper, we tested this hypothesis using backward masking. We showed, in two different experiments per country of origin, to participants in Britain, Chile, New Zealand and Singapore, backward masked own and other-culture emotional faces. We assessed detection and recognition performance, and self-reports for emotionality and familiarity. We presented thorough cross-cultural experimental evidence that when using Bayesian assessment of non-parametric receiver operating characteristics and hit-versus-miss detection and recognition response analyses, masked faces showing own cultural dialects of emotion were rated higher for emotionality and familiarity compared to other-culture emotional faces and that this effect involved conscious awareness.

Mental imagery is the process through which we retrieve and recombine information from our memory to elicit the subjective impression of “seeing with the mind’s eye”. In the social domain, we imagine other individuals while recalling our encounters with them or modelling alternative social interactions in future. Many studies using imaging and neurophysiological techniques have shown several similarities in brain activity between visual imagery and visual perception, and have identified frontoparietal, occipital and temporal neural components of visual imagery. However, the neural connectivity between these regions during visual imagery of socially relevant stimuli has not been studied. Here we used electroencephalography to investigate neural connectivity and its dynamics between frontal, parietal, occipital and temporal electrodes during visual imagery of faces. We found that voluntary visual imagery of faces is associated with long-range phase synchronisation in the gamma frequency range between frontoparietal electrode pairs and between occipitoparietal electrode pairs. In contrast, no effect of imagery was observed in the connectivity between occipitotemporal electrode pairs. Gamma range synchronisation between occipitoparietal electrode pairs predicted subjective ratings of the contour definition of imagined faces. Furthermore, we found that visual imagery of faces is associated with an increase of short-range frontal synchronisation in the theta frequency range, which temporally preceded the long-range increase in the gamma synchronisation. We speculate that the local frontal synchrony in the theta frequency range might be associated with an effortful top-down mnemonic reactivation of faces. In contrast, the long-range connectivity in the gamma frequency range along the fronto-parieto-occipital axis might be related to the endogenous binding and subjective clarity of facial visual features.

The theory of universal emotions suggests that certain emotions such as fear, anger, disgust, sadness, surprise and happiness can be encountered cross-culturally. These emotions are expressed using specific facial movements that enable human communication. More recently, theoretical and empirical models have been used to propose that universal emotions could be expressed via discretely different facial movements in different cultures due to the non-convergent social evolution that takes place in different geographical areas. This has prompted the consideration that own-culture emotional faces have distinct evolutionary important sociobiological value and can be processed automatically, and without conscious awareness. In this paper, we tested this hypothesis using backward masking. We showed, in two different experiments per country of origin, to participants in Britain, Chile, New Zealand and Singapore, backward masked own and other-culture emotional faces. We assessed detection and recognition performance, and self-reports for emotionality and familiarity. We presented thorough cross-cultural experimental evidence that when using Bayesian assessment of non-parametric receiver operating characteristics and hit-versus-miss detection and recognition response analyses, masked faces showing own cultural dialects of emotion were rated higher for emotionality and familiarity compared to other-culture emotional faces and that this effect involved conscious awareness.

Human faces convey essential information for understanding others’ mental states and intentions. The importance of faces in social interaction has prompted suggestions that some relevant facial features such as configural information, emotional expression, and gaze direction may promote preferential access to awareness. This evidence has predominantly come from interocular suppression studies, with the most common method being the Breaking Continuous Flash Suppression (bCFS) procedure, which measures the time it takes different stimuli to overcome interocular suppression. However, the procedures employed in such studies suffer from multiple methodological limitations. For example, they are unable to disentangle detection from identification processes, their results may be confounded by participants’ response bias and decision criteria, they typically use small stimulus sets, and some of their results attributed to detecting high-level facial features (e.g., emotional expression) may be confounded by differences in low-level visual features (e.g., contrast, spatial frequency). In this article, we review the evidence from the bCFS procedure on whether relevant facial features promote access to awareness, discuss the main limitations of this very popular method, and propose strategies to address these issues.

Human vision is sensitive enough to detect a single photon, but the minimal exposure required to extractmeaningfrom stimulation – arguably the visual system’s function – remains unknown. This requirement cannot be characterised in terms of stimulus energy, because the system is differentially sensitive to attributes that are distinguished by stimulus configuration rather than physical amplitude. Observers can extract large amounts of information from brief displays; but for given display durations, certain types of information are discerned more readily than others, suggesting that visual pathways prioritise certain stimulus properties. Determining theminimalexposure durations required for processing various aspects of a visual stimulus can thus shed light on the system’s priorities. Technical limitations have so far prevented measurement of such minima; here, we used a novel technique enabling arbitrarily brief displays with microsecond-level precision to establish the minimal durations required for processing human faces, a stimulus category whose perception is associated with several well-characterised behavioural and neural markers. We found that neural and psychophysical measures converged to reveal a sequence of distinct minimal exposures required for object-level detection (1-2 ms), face-specific processing (3-4 ms), and emotion-specific processing (4-5 ms). Our findings resolve debates about factors that may facilitate processing: Face orientation affected minimal exposure, but emotional expression did not. Awareness emerged with detection; we found no evidence of subliminal perception. These findings critically inform theories of visual processing and awareness by elucidating the information to which the visual system is attuned.

Hypnotic suggestions can produce a broad range of perceptual experiences, including hallucinations. Visual hypnotic hallucinations differ in many ways from regular mental images. For example, they are usually experienced as automatic, vivid, and real images, typically compromising the sense of reality. While both hypnotic hallucination and mental imagery are believed to mainly rely on the activation of the visual cortex via top-down mechanisms, it is unknown how they differ in the neural processes they engage. Here we used an adaptation paradigm to test and compare top-down processing between hypnotic hallucination, mental imagery, and visual perception in very highly hypnotisable individuals whose ability to hallucinate was assessed. By measuring the N170/VPP event-related complex and using multivariate decoding analysis, we found that hypnotic hallucination of faces involves greater top-down activation of sensory processing through lateralised neural mechanisms in the right hemisphere compared to mental imagery. Our findings suggest that the neural signatures that distinguish hypnotically hallucinated faces from imagined faces lie in the right brain hemisphere.

The dialects theory of cross-cultural communication suggests that due to culture-specific characteristics in the expression of emotion, we can recognise own-culture emotional expressions more accurately than other-culture emotional expressions. This effect is suggested to occur due to the nonconvergent social evolution that takes place in different geographical regions. Based on the evolutionary value of own-culture social signals, previous research has suggested that own-culture emotional expressions can be appraised without conscious awareness. The current study tested this hypothesis. We developed, validated, and made open access what is to our knowledge the first labelled, multicultural facial stimuli set, including freely expressed and Facial Action Coding System instructed emotional expressions. We assessed emotional recognition and cultural familiarity responses during brief backward-masked presentations in British participants. We found that emotional recognition and cultural familiarity were higher for own-culture faces. A Bayesian analysis of face-detection and emotional-recognition performance revealed that faces were not processed subliminally. Further analysis of awareness, using hits (correct detection/recognition) and misses (incorrect detection/recognition), showed that face-detection hits were a necessary condition for reporting higher familiarity for own-culture faces. These findings suggest that the own-culture emotional recognition advantage is preserved under conditions of backwards masking and that the appraisal of cultural familiarity involves conscious awareness.

Hypnotic suggestions can produce a broad range of perceptual experiences, including hallucinations. Visual hypnotic hallucinations differ in many ways from regular mental images. For example, they are usually experienced as automatic, vivid, and real images, typically compromising the sense of reality. While both hypnotic hallucination and mental imagery are believed to mainly rely on the activation of the visual cortex via top-down mechanisms, it is unknown how they differ in the neural processes they engage. Here we used an adaptation paradigm to test and compare top-down processing between hypnotic hallucination, mental imagery, and visual perception in very highly hypnotisable individuals whose ability to hallucinate was assessed. By measuring the N170/VPP event-related complex and using multivariate decoding analysis, we found that hypnotic hallucination of faces involves greater top-down activation of sensory processing through lateralised mechanisms in the right hemisphere compared to mental imagery. Our findings suggest that the neural signatures that distinguish hypnotically hallucinated faces from imagined faces lie in the right brain hemisphere.

Mental imagery is the process through which we retrieve and recombine information from our memory to elicit the subjective impression of "seeing with the mind's eye". In the social domain, we imagine other individuals while recalling our encounters with them or modelling alternative social interactions in future. Many studies using imaging and neurophysiological techniques have shown several similarities in brain activity between visual imagery and visual perception, and have identified frontoparietal, occipital and temporal neural components of visual imagery. However, the neural connectivity between these regions during visual imagery of socially relevant stimuli has not been studied. Here we used electroencephalography to investigate neural connectivity and its dynamics between frontal, parietal, occipital and temporal electrodes during visual imagery of faces. We found that voluntary visual imagery of faces is associated with long-range phase synchronisation in the gamma frequency range between frontoparietal electrode pairs and between occipitoparietal electrode pairs. In contrast, no effect of imagery was observed in the connectivity between occipitotemporal electrode pairs. Gamma range synchronisation between occipitoparietal electrode pairs predicted subjective ratings of the contour definition of imagined faces. Furthermore, we found that visual imagery of faces is associated with an increase of short-range frontal synchronisation in the theta frequency range, which temporally preceded the long-range increase in the gamma synchronisation. We speculate that the local frontal synchrony in the theta frequency range might be associated with an effortful top-down mnemonic reactivation of faces. In contrast, the long-range connectivity in the gamma frequency range along the fronto-parieto-occipital axis might be related to the endogenous binding and subjective clarity of facial visual features.

Faces convey information essential for social interaction. Their importance has prompted suggestions that some facial features may be processed unconsciously. Although some studies have provided empirical support for this idea, it remains unclear whether these findings were due to perceptual processing or to post-perceptual decisional factors. Evidence for unconscious processing of facial features has predominantly come from the Breaking Continuous Flash Suppression (b-CFS) paradigm, which measures the time it takes different stimuli to overcome interocular suppression. For example, previous studies have found that upright faces are reported faster than inverted faces, and direct-gaze faces are reported faster than averted-gaze faces. However, this procedure suffers from important problems: Observers can decide how much information they receive before committing to a report, so their detection responses may be influenced by differences in decision criteria and by stimulus identification. Here, we developed a new procedure that uses predefined exposure durations, enabling independent measurement of perceptual sensitivity and decision criteria. We found higher detection sensitivity to both upright and direct-gaze (compared to inverted and averted-gaze) faces, with no effects on decisional factors. For identification, we found both greater sensitivity and more liberal criteria for upright faces. Our findings demonstrate that face orientation and gaze direction influence perceptual sensitivity, indicating that these facial features may be processed unconsciously.

Mental imagery is the process through which we retrieve and recombine information from our memory to elicit the subjective impression of “seeing with the mind’s eye”. In the social domain, we imagine other individuals while recalling our encounters with them or modelling alternative social interactions in future. Many studies using imaging and neurophysiological techniques have shown several similarities in brain activity between visual imagery and visual perception, and have identified frontoparietal, occipital and temporal neural components of visual imagery. However, the neural connectivity between these regions during visual imagery of socially relevant stimuli have not been studied. Here we used electroencephalography to investigate neural connectivity and its dynamics between frontal, parietal, occipital and temporal electrodes during visual imagery of faces. We found that voluntary visual imagery of faces is associated with long-range phase synchronisation in the gamma frequency range between frontoparietal electrode pairs and between occipitoparietal electrode pairs. In contrast, no effect of imagery was observed in the connectivity between occipitotemporal electrode pairs. Gamma range synchronisation between occipitoparietal electrode pairs predicted subjective ratings of the contour definition of imagined faces. Furthermore, we found that visual imagery of faces is associated with an increase of short-range frontal synchronisation in the theta frequency range, which temporally preceded the long-range increase in the gamma synchronisation. We speculate that the local frontal synchrony in the theta frequency range might be associated with an effortful top-down mnemonic reactivation of faces. In contrast, the long-range connectivity in the gamma frequency range along the fronto-parieto-occipital axis might be related to the endogenous binding and subjective clarity of facial visual features.

Andy Wickens, profesor titular de psicologia y neurociencia en la University of Central Lancashire, Reino Unido, nos entrega este motivador y detallado libro que pretende, con gran exito, exponer el devenir historico del estudio del cerebro, tanto en lo que respecta a su comprension filosofica como fisiologica. Y, ademas, respecto a como esta ultima se empotra sobre la primera, dejando entrever el bosquejo de los supuestos epistemologicos que asientan nuestra actual comprension en neurologia, psiquiatria y psicologia. Los primeros dos capitulos se hacen cargo de exponer de que manera las personas de la edad de piedra y de civilizaciones que brillaron en las postrimerias de la prehistoria, se explicaban el origen y la mecanica subyacente de la conducta y de la actividad mental. Que rol le atribuian al cerebro y mediante que metodos llegaban a sus conclusiones, ya fuesen estos mas cercanos a la especulacion o la experiencia empirica. Y, posteriormente, el largo y sinuoso camino hacia las experiencias de Galeno y su legado, ya en el siglo II d. C. Del tercer capitulo al sexto, se presentan eventos relevantes ocurridos entre la tardia Edad Antigua hasta el Siglo de las Luces, periodo en el cual tal vez ocurrieron la mayor parte de las transformaciones filosoficas en la comprension del sistema nervioso: por una parte, los aportes en neuroanatomia de Mondino de Luzzi, Leonardo Da Vinci, Andreas Vesalius y el asentamiento de la teoria celular. Por otra parte, la filosofia metafisica de Rene Descartes, las contribuciones a la fisiologia de Thomas Willis y Albrecht von Haller y, asi, dando un paso mas firme hacia el quehacer cientifico, la incorporacion del descubrimiento de la electricidad en los animales, el uso del galvanometro y el descubrimiento de los potenciales de accion. Finalmente, el ascenso y la caida de la frenologia, disciplina que, si bien incurrio en numerosos errores metodologicos, instauro la idea de que las funciones mentales podian tener una localizacion cerebral.

Sr. Editor: El avance de las neurociencias en materia de cognicion social ha sido notable, especialmente a lo largo de la ultima decada. En este campo, el estudio de la empatia ha logrado un espacio ciertamente privilegiado gracias al uso cada vez mas detallado de tecnicas como electroencefalografia (EEG) y potenciales asociados a eventos (ERPs), resonancia magnetica funcional (fMRI), tecnicas de seguimiento de ojos (eye-tracking), magnetoencefalografia (MEG) y electromiografia (EMG). Los estudios realizados con esta ultima, curiosamente, suelen no recibir la atencion que reciben tecnicas mas populares como fMRI y EEG. Sin embargo, su uso ha sido crucial para desentranar aspectos de la empatia en el contexto de la comunicacion no verbal y la construccion de vinculos afectivos, entre los cuales encontramos el fenomeno de la mimica facial. Este fenomeno ha sido descrito como la tendencia involuntaria a imitar la expresion facial de otro individuo, especialmente cuando esta involucra una carga emocional. La mimica facial ha sido estudiada principalmente utilizando EMG, especificamente midiendo la actividad del musculo cigomatico mayor (MCM) y del musculo corrugador superciliar (MCS), en la mayoria de los casos, como marcadores para expresion facial de alegria y expresion facial de enojo, respectivamente (1). Esta sincronia facial es considerada como un importante contribuyente en la respuesta empatica y el contagio emocional (2), encontrandose presente incluso al percibir estimulos faciales de manera subliminal. Leer mas...

To study voluntary action a dissociation must be established between the somatic event (e.g, motor action) and what the agent voluntarily does (e.g, handing a tool to a friend). We propose that cognitive neuroscience studies of hypnotic suggestion can accomplish this dissociation between action and will (more specifically, between action and intention, or action and volition). Thus, hypnotic suggestion may afford an empirical testing ground to study voluntary action, distinguishing voluntariness from action.