The determinants of consciousness of human faces

Distrust before first sight? Examining knowledge- and appearance-based effects of trustworthiness on the visual consciousness of faces

The present EEG study with 32 healthy participants investigated whether affective knowledge about a person influences the visual awareness of their face, additionally considering the impact of facial appearance. Faces differing in perceived trustworthiness based on appearance were associated with negative or neutral social information and shown as target stimuli in an attentional blink task. As expected, participants showed enhanced awareness of faces associated with negative compared to neutral social information. On the neurophysiological level, this effect was connected to differences in the time range of the early posterior negativity (EPN)-a component associated with enhanced attention and facilitated processing of emotional stimuli. The findings indicate that the social-affective relevance of a face based on emotional knowledge is accessed during a phase of attentional enhancement for conscious perception and can affect prioritization for awareness. In contrast, no clear evidence for influences of facial trustworthiness during the attentional blink was found.

The importance of awareness in face processing: A critical review of interocular suppression studies

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.

A Cross-Cultural Replication on Humanness Attribution

Abstract. Previous research showed that targets achieving (vs. not) a goal were ascribed more humanness. We conceptually replicate previous studies by involving a population of English and Arabic speakers to test cross-cultural replicability of the effect and the contribution of sensorimotor systems in agency representation. Participants ( Ntot = 637) saw animations, where goal achievement and trajectory were manipulated. They evaluated agency, communion, humanness, and attitudes (respect and liking) toward presented targets. Goal achievement versus failure but not movement trajectory increased agency and communion ratings, which in turn affected humanness, respect, and liking (Study 1 and Study 2). Goal manipulation also directly affected humanness ratings (Study 2). Altogether, our findings suggest a superior role of success over trajectory manipulation in perceiving inanimate objects as having humanness.

Illusory faces are more likely to be perceived as male than female

Face pareidolia is the phenomenon of perceiving illusory faces in inanimate objects. Here we show that illusory faces engage social perception beyond the detection of a face: they have a perceived age, gender, and emotional expression. Additionally, we report a striking bias in gender perception, with many more illusory faces perceived as male than female. As illusory faces do not have a biological sex, this bias is significant in revealing an asymmetry in our face evaluation system given minimal information. Our result demonstrates that the visual features that are sufficient for face detection are not generally sufficient for the perception of female. Instead, the perception of a nonhuman face as female requires additional features beyond that required for face detection.

Despite our fluency in reading human faces, sometimes we mistakenly perceive illusory faces in objects, a phenomenon known as face pareidolia. Although illusory faces share some neural mechanisms with real faces, it is unknown to what degree pareidolia engages higher-level social perception beyond the detection of a face. In a series of large-scale behavioral experiments (n_total = 3,815 adults), we found that illusory faces in inanimate objects are readily perceived to have a specific emotional expression, age, and gender. Most strikingly, we observed a strong bias to perceive illusory faces as male rather than female. This male bias could not be explained by preexisting semantic or visual gender associations with the objects, or by visual features in the images. Rather, this robust bias in the perception of gender for illusory faces reveals a cognitive bias arising from a broadly tuned face evaluation system in which minimally viable face percepts are more likely to be perceived as male.

Regression to the Mean Does Not Explain Away Nonconscious Processing

In studies that use subliminal presentations, participants may become aware of stimuli that are intended to remain subliminal. A common solution to this problem is to analyze the results of the group of participants for whom the stimuli remained subliminal. A recent article (Shanks, 2017) argued that this method leads to a regression to the mean artifact, which may account for many of the observed effects. However, conceptual and statistical characteristics of the original publication lead to overestimation of the influence of the artifact. Using simulations, we demonstrate that this overestimation leads to the mistaken conclusion that regression to the mean accounts for nonconscious effects. We conclude by briefly outlining a new description of the influence of the artifact and how it should be statistically addressed.

From non-conscious processing to conscious events: a minimalist approach

The minimalist approach that we develop here is a framework that allows to appreciate how non-conscious processing and conscious contents shape human cognition, broadly defined. It is composed of three simple principles. First, cognitive processes are inherently non-conscious, while their inputs and (interim) outputs may be consciously experienced. Second, non-conscious processes and elements of the cognitive architecture prioritize information for conscious experiences. Third, conscious events are composed of series of conscious contents and non-conscious processes, with increased duration leading to more opportunity for processing. The narrowness of conscious experiences is conceptualized here as a solution to the problem of channeling the plethora of non-conscious processes into action and communication processes that are largely serial. The framework highlights the importance of prioritization for consciousness, and we provide an illustrative review of three main factors that shape prioritization-stimulus strength, motivational relevance and mental accessibility. We further discuss when and how this framework (i) is compatible with previous theories, (ii) enables new understandings of established findings and models, and (iii) generates new predictions and understandings.

Four dimensions characterize attributions from faces using a representative set of English trait words

People readily (but often inaccurately) attribute traits to others based on faces. While the details of attributions depend on the language available to describe social traits, psychological theories argue that two or three dimensions (such as valence and dominance) summarize social trait attributions from faces. However, prior work has used only a small number of trait words (12 to 18), limiting conclusions to date. In two large-scale, preregistered studies we ask participants to rate 100 faces (obtained from existing face stimuli sets), using a list of 100 English trait words that we derived using deep neural network analysis of words that have been used by other participants in prior studies to describe faces. In study 1 we find that these attributions are best described by four psychological dimensions, which we interpret as “warmth”, “competence”, “femininity”, and “youth”. In study 2 we partially reproduce these four dimensions using the same stimuli among additional participant raters from multiple regions around the world, in both aggregated and individual-level data. These results provide a comprehensive characterization of trait attributions from faces, although we note our conclusions are limited by the scope of our study (in particular we note only white faces and English trait words were included).

People form impressions about others from seeing their faces, and use many words to describe those impressions. Here, using ratings of 100 representatively sampled white adult faces on a large set of traits, the authors show that trait impressions from faces can be summarized by four psychological dimensions.

Dissociating conscious and unconscious influences on visual detection effects

The scope of unconscious processing is highly debated, with recent studies showing that even high-level functions such as perceptual integration and category-based attention occur unconsciously. For example, upright faces that are suppressed from awareness through interocular suppression break into awareness more quickly than inverted faces. Similarly, verbal object cues boost otherwise invisible objects into awareness. Here, we replicate these findings, but find that they reflect a general difference in detectability not specific to interocular suppression. To dissociate conscious and unconscious influences on visual detection effects, we use an additional discrimination task to rule out conscious processes as a cause for these differences. Results from this detection-discrimination dissociation paradigm reveal that, while face orientation is processed unconsciously, category-based attention requires awareness. These findings provide insights into the function of conscious perception and offer an experimental approach for mapping out the scope and limits of unconscious processing.

Did you see it? Robust individual differences in the speed with which meaningful visual stimuli break suppression

Perceptual conscious experiences result from non-conscious processes that precede them. We document a new characteristic of the cognitive system: the speed with which visual meaningful stimuli are prioritized to consciousness over competing noise in visual masking paradigms. In ten experiments (N = 399) we find that an individual's non-conscious visual prioritization speed (NVPS) is ubiquitous across a wide variety of stimuli, and generalizes across visual masks, suppression tasks, and time. We also find that variation in NVPS is unique, in that it cannot be explained by variation in general speed, perceptual decision thresholds, short-term visual memory, or three networks of attention (alerting, orienting and executive). Finally, we find that NVPS is correlated with subjective measures of sensitivity, as they are measured by the Highly Sensitive Person scale. We conclude by discussing the implications of variance in NVPS for understanding individual variance in behavior and the neural substrates of consciousness.

Social categorization and joint attention: Interacting effects of age, sex, and social status

In the present study, we examine how person categorization conveyed by the combination of multiple cues modulates joint attention. In three experiments, we tested the combinatory effect of age, sex, and social status on gaze-following behaviour and pro-social attitudes. In Experiments 1 and 2, young adults were required to perform an instructed saccade towards left or right targets while viewing a to-be-ignored distracting face (female or male) gazing left or right, that could belong to a young, middle-aged, or elderly adult of high or low social status. Social status was manipulated by semantic knowledge (Experiment 1) or through visual appearance (Experiment 2). Results showed a clear combinatory effect of person perception cues on joint attention (JA). Specifically, our results showed that age and sex cues interacted with social status information depending on the modality through which it was conveyed. In Experiment 3, we further investigated our results by testing whether the identities used in Experiments 1 and 2 triggered different pro-social behaviour. The results of Experiment 3 showed that the identities resulting as more distracting in Experiments 1 and 2 were also perceived as more in need and prompt helping behaviour. Taken together, our evidence shows a combinatorial effect of age, sex, and social status in modulating the gaze following behaviour, highlighting a complex and dynamic interplay between person categorization and joint attention.

Unsupervised inference approach to facial attractiveness

The perception of facial attractiveness is a complex phenomenon which depends on how the observer perceives not only individual facial features, but also their mutual influence and interplay. In the machine learning community, this problem is typically tackled as a problem of regression of the subject-averaged rating assigned to natural faces. However, it has been conjectured that this approach does not capture the complexity of the phenomenon. It has recently been shown that different human subjects can navigate the face-space and "sculpt" their preferred modification of a reference facial portrait. Here we present an unsupervised inference study of the set of sculpted facial vectors in such experiments. We first infer minimal, interpretable and accurate probabilistic models (through Maximum Entropy and artificial neural networks) of the preferred facial variations, that encode the inter-subject variance. The application of such generative models to the supervised classification of the gender of the subject that sculpted the face reveals that it may be predicted with astonishingly high accuracy. We observe that the classification accuracy improves by increasing the order of the non-linear effective interaction. This suggests that the cognitive mechanisms related to facial discrimination in the brain do not involve the positions of single facial landmarks only, but mainly the mutual influence of couples, and even triplets and quadruplets of landmarks. Furthermore, the high prediction accuracy of the subjects' gender suggests that much relevant information regarding the subjects may influence (and be elicited from) their facial preference criteria, in agreement with the multiple motive theory of attractiveness proposed in previous works.

Getting to the heart of it: Multi-method exploration of nonconscious prioritization processes

Understanding the determinants of consciousness is crucial for theories that see it as functionally adaptive, and for explaining how consciousness affects higher-level cognition. The invention of continuous flash suppression (CFS), a long-duration suppression technique, resulted in a proliferation of research into the process of prioritization for consciousness. We developed a new technique, repeated masked suppression (RMS), that facilitates the measurement of long suppression times, but relies on different visual principles. RMS enables a theoretical leap: It allows scientists to examine the central process of prioritization across different suppression methods. In five experiments (n = 282) we collected chronometric RMS and CFS data, finding that the previously reported face inversion effect and the face priority-dimension generalize beyond CFS. Our results validate the use of multi-method designs in the study of prioritization for consciousness. Furthermore, we show how RMS could be used online to reach diverse samples, previously beyond the reach of consciousness science.

An objective and reliable electrophysiological marker for implicit trustworthiness perception

Trustworthiness is assumed to be processed implicitly from faces, despite the fact that the overwhelming majority of research has only involved explicit trustworthiness judgements. To answer the question whether or not trustworthiness processing can be implicit, we apply an electroencephalography fast periodic visual stimulation (FPVS) paradigm, where electrophysiological cortical activity is triggered in synchrony with facial trustworthiness cues, without explicit judgements. Face images were presented at 6 Hz, with facial trustworthiness varying at 1 Hz. Significant responses at 1 Hz were observed, indicating that differences in the trustworthiness of the faces were reflected in the neural signature. These responses were significantly reduced for inverted faces, suggesting that the results are associated with higher order face processing. The neural responses were reliable, and correlated with explicit trustworthiness judgements, suggesting that the technique is capable of picking up on stable individual differences in trustworthiness processing. By demonstrating neural activity associated with implicit trustworthiness judgements, our results contribute to resolving a key theoretical debate. Moreover, our data show that FPVS is a valuable tool to examine face processing at the individual level, with potential application in pre-verbal and clinical populations who struggle with verbalization, understanding or memory.

Novel procedure for generating continuous flash suppression: Seurat meets Mondrian

Continuous flash suppression (CFS) entails presentation of a stationary target to one eye and an animated sequence of arrays of geometric figures, the mask, to the other eye. The prototypical CFS sequence comprises different sized rectangles of various colors, dubbed Mondrians. Presented as a rapid, changing sequence to one eye, Mondrians or other similarly constructed textured arrays can abolish awareness of the target viewed by the other eye for many seconds at a time, producing target suppression durations much longer than those associated with conventional binocular rivalry. We have devised an animation technique that replaces meaningless Mondrian figures with recognizable visual objects and scenes as inducers of CFS, allowing explicit manipulation of the visual semantic content of those masks. By converting each image of these CFS sequences into successively presented objects or scenes each comprised of many small, circular patches of color, we create pointillist CFS sequences closely matched in terms of their spatio-temporal power spectra. Randomly rearranging the positions of the pointillist patches scrambles the images so they are no longer recognizable. CFS sequences comprising a stream of different objects produces more robust interocular suppression than do sequences comprising a stream of different scenes, even when the two categories of CFS are matched in root mean square contrast and spatial frequency content. Factors promoting these differences in CFS potency could range from low-level, image-based features to high-level factors including attention and recognizability. At the same time, object- and scene-based CFS sequences, when themselves suppressed from awareness, do not differ in their durations of suppression, implying that semantic content of those images comprising CFS sequences are not registered during suppression. The pointillist technique itself offers a potentially useful means for examining the impact of high-level image meaning on aspects of visual perception other than interocular suppression.

The Role of Gender in the Preconscious Processing of Facial Trustworthiness and Dominance

The present study adopted the breaking continuous flash suppression paradigm (b-CFS) to investigate how Chinese participants process trustworthiness (Experiment 1) and dominance (Experiment 2) at the preconscious level. In addition, we tested whether the gender of a face and the gender of a participant can influence the preconscious processing of facial trustworthiness and dominance. Experiment 1 showed that the least and most trustworthy faces both took significantly less time to break into awareness than neutral faces. In Experiment 2, for female faces, neutral faces took significantly less time to break into awareness than the least and most dominant faces. In both experiments, female faces broke through suppression faster than male faces. In summary, for Chinese participants, the preconscious processing of trustworthiness was not different between male and female faces. However, the preconscious processing of dominance was different between male and female faces.

Subjectivity and complexity of facial attractiveness

The origin and meaning of facial beauty represent a longstanding puzzle. Despite the profuse literature devoted to facial attractiveness, its very nature, its determinants and the nature of inter-person differences remain controversial issues. Here we tackle such questions proposing a novel experimental approach in which human subjects, instead of rating natural faces, are allowed to efficiently explore the face-space and "sculpt" their favorite variation of a reference facial image. The results reveal that different subjects prefer distinguishable regions of the face-space, highlighting the essential subjectivity of the phenomenon. The different sculpted facial vectors exhibit strong correlations among pairs of facial distances, characterising the underlying universality and complexity of the cognitive processes, and the relative relevance and robustness of the different facial distances.

Effects of dominance and prestige based social status on competition for attentional resources

Social status can be attained through either dominance (coercion and intimidation) or prestige (skill and respect). Individuals high in either of these status pathways are known to more readily attract gaze and covert spatial attention compared to their low-status counterparts. However it is not known if social status biases allocation of attentional resources to competing stimuli. To address this issue, we used an attentional blink paradigm to explore non-spatial attentional biases in response to face stimuli varying in dominance and prestige. Results from a series of studies consistently indicated that participants were biased towards allocating attention to low- relative to high- dominance faces. We also observed no effects of manipulating prestige on attentional bias. We attribute our results to the workings of comparatively early processing stages, separate from those mediating spatial attention shifts, which are tuned to physical features associated with low dominance. These findings challenge our current understanding of the impact of social status on attentional competition.

Is Man the Measure of All Things? A Social Cognitive Account of Androcentrism

Androcentrism refers to the propensity to center society around men and men's needs, priorities, and values and to relegate women to the periphery. Androcentrism also positions men as the gender-neutral standard while marking women as gender-specific. Examples of androcentrism include the use of male terms (e.g., he), images, and research participants to represent everyone. Androcentrism has been shown to have serious consequences. For example, women's health has been adversely affected by over-generalized medical research based solely on male participants. Nonetheless, relatively little is known about androcentrism's proximate psychological causes. In the present review, we propose a social cognitive perspective arguing that both social power and categorization processes are integral to understanding androcentrism. We present and evaluate three possible pathways to androcentrism deriving from (a) men being more frequently instantiated than women, (b) masculinity being more "ideal" than femininity, and/or (c) masculinity being more common than femininity.