When the Whites of the Eyes are Red: A Uniquely Human Cue

Redness of the human eye is produced primarily by vasodilation of blood vessels of the conjunctiva, a membrane positioned over the sclera, the eye’s tough, white outer layer. Reddened eyes are a uniquely human cue because other primates lack the background of white sclera necessary to make the reddened conjunctiva visible. This study evaluates red eyes as a social and biological cue by contrasting the perception of eyes with normal ‘whites’ with copies of those eyes whose sclera were reddened by digital editing. Individuals with reddened sclera were perceived as sadder, less healthy, and less attractive than individuals with normal (white) sclera. Scleral whiteness joins such cues as smooth skin, long, lustrous hair, symmetry, averageness and sexually dimorphic traits as signs of health, beauty and reproductive fitness.     

Red, Yellow, and Super-White Sclera

The sclera, the eye’s tough outer layer, is, among primates, white only in humans, providing the ground necessary for the display of colors that vary in health and disease. The current study evaluates scleral color as a cue of socially significant information about health, attractiveness, and age by contrasting the perception of eyes with normal whites with copies of those eyes whose whites were reddened, yellowed, or further whitened by digital editing. Individuals with red and yellow sclera were rated to be less healthy, less attractive, and older than individuals with untinted control sclera. Individuals with whitened, “super-white” sclera were rated as younger, although not more healthy or attractive, than controls. In humans, clear, white sclera may join such traits as smooth skin and long, lustrous hair as signs of health, beauty, and reproductive fitness. The evolution of a white sclera may have contributed to the emergence of humans as a social species.     

On the time course of vocal emotion recognition

How quickly do listeners recognize emotions from a speaker''s voice, and does the time course for recognition vary by emotion type? To address these questions, we adapted the auditory gating paradigm to estimate how much vocal information is needed for listeners to categorize five basic emotions (anger, disgust, fear, sadness, happiness) and neutral utterances produced by male and female speakers of English. Semantically-anomalous pseudo-utterances (e.g., The rivix jolled the silling) conveying each emotion were divided into seven gate intervals according to the number of syllables that listeners heard from sentence onset. Participants (n = 48) judged the emotional meaning of stimuli presented at each gate duration interval, in a successive, blocked presentation format. Analyses looked at how recognition of each emotion evolves as an utterance unfolds and estimated the “identification point” for each emotion. Results showed that anger, sadness, fear, and neutral expressions are recognized more accurately at short gate intervals than happiness, and particularly disgust; however, as speech unfolds, recognition of happiness improves significantly towards the end of the utterance (and fear is recognized more accurately than other emotions). When the gate associated with the emotion identification point of each stimulus was calculated, data indicated that fear (M = 517 ms), sadness (M = 576 ms), and neutral (M = 510 ms) expressions were identified from shorter acoustic events than the other emotions. These data reveal differences in the underlying time course for conscious recognition of basic emotions from vocal expressions, which should be accounted for in studies of emotional speech processing.     

Discrete Neural Correlates for the Recognition of Negative Emotions: Insights from Frontotemporal Dementia

Patients with frontotemporal dementia have pervasive changes in emotion recognition and social cognition, yet the neural changes underlying these emotion processing deficits remain unclear. The multimodal system model of emotion proposes that basic emotions are dependent on distinct brain regions, which undergo significant pathological changes in frontotemporal dementia. As such, this syndrome may provide important insight into the impact of neural network degeneration upon the innate ability to recognise emotions. This study used voxel-based morphometry to identify discrete neural correlates involved in the recognition of basic emotions (anger, disgust, fear, sadness, surprise and happiness) in frontotemporal dementia. Forty frontotemporal dementia patients (18 behavioural-variant, 11 semantic dementia, 11 progressive nonfluent aphasia) and 27 healthy controls were tested on two facial emotion recognition tasks: The Ekman 60 and Ekman Caricatures. Although each frontotemporal dementia group showed impaired recognition of negative emotions, distinct associations between emotion-specific task performance and changes in grey matter intensity emerged. Fear recognition was associated with the right amygdala; disgust recognition with the left insula; anger recognition with the left middle and superior temporal gyrus; and sadness recognition with the left subcallosal cingulate, indicating that discrete neural substrates are necessary for emotion recognition in frontotemporal dementia. The erosion of emotion-specific neural networks in neurodegenerative disorders may produce distinct profiles of performance that are relevant to understanding the neurobiological basis of emotion processing.     

Discrete emotion effects on lexical decision response times

Our knowledge about affective processes, especially concerning effects on cognitive demands like word processing, is increasing steadily. Several studies consistently document valence and arousal effects, and although there is some debate on possible interactions and different notions of valence, broad agreement on a two dimensional model of affective space has been achieved. Alternative models like the discrete emotion theory have received little interest in word recognition research so far. Using backward elimination and multiple regression analyses, we show that five discrete emotions (i.e., happiness, disgust, fear, anger and sadness) explain as much variance as two published dimensional models assuming continuous or categorical valence, with the variables happiness, disgust and fear significantly contributing to this account. Moreover, these effects even persist in an experiment with discrete emotion conditions when the stimuli are controlled for emotional valence and arousal levels. We interpret this result as evidence for discrete emotion effects in visual word recognition that cannot be explained by the two dimensional affective space account.     

Emotion recognition in children and adolescents with attention-deficit/hyperactivity disorder (ADHD)

Children with attention-deficit/hyperactivity disorder (ADHD) are impaired in social adaptation and display deficits in social competence. Deficient emotion recognition has been discussed to underlie these social problems. However, comorbid conduct problems have not been considered in the majority of studies conducted so far, and the influence of medication on emotion recognition has rarely been studied. Here, emotion recognition performance was assessed in children with ADHD without medication compared with children with ADHD under stimulant medication and a matched control group. In order to rule out confounding by externalizing symptoms, children with comorbid conduct problems were excluded. Video clips with neutral faces developing a basic emotion (happiness, sadness, disgust, fear and anger) were presented in order to assess emotion recognition. Results indicated between-group differences neither concerning the number of correctly identified emotions nor concerning reaction times and their standard deviations. Thus, we suggest that ADHD per se is not associated with deficits in emotion recognition.     

Neurophysiological correlates of induced discrete emotions in humans: an individual analysis

The present study addressed EEG pattering during experimentally manipulated emotion. Film clips previously shown to induce happiness,joy, anger, disgust, fear/anxiety, sadness, as well as neutral control films, were presented to 30 university students while a 62-channel EEG was recorded, and a self-reported effect was described. Analyses revealed both emotion-specific and emotion-unspecific EEG pattering for the emotions under study. Induced positive and negative emotions were accompanied by hemispheric activation asymmetries in theta-2, alpha-2, and beta-1 EEG frequency bands. Emotions of joy and disgust induced lateralized a theta-2 power increase in anterior-temporal and frontal regions of the left hemisphere reflecting involvement of cognitive mechanisms in the emotional processing. Negative emotions of disgust and fear/anxiety were characterized by alpha-2 and beta-1 desynchronization of the right temporal-parietal cortex, suggesting its involvement in modulation of the emotion-related arousal.     

On the Validity of the Autobiographical Emotional Memory Task for Emotion Induction

The Autobiographical Emotional Memory Task (AEMT), which involves recalling and writing about intense emotional experiences, is a widely used method to experimentally induce emotions. The validity of this method depends upon the extent to which it can induce specific desired emotions (intended emotions), while not inducing any other (incidental) emotions at different levels across one (or more) conditions. A review of recent studies that used this method indicated that most studies exclusively monitor post-writing ratings of the intended emotions, without assessing the possibility that the method may have differentially induced other incidental emotions as well. We investigated the extent of this issue by collecting both pre- and post-writing ratings of incidental emotions in addition to the intended emotions. Using methods largely adapted from previous studies, participants were assigned to write about a profound experience of anger or fear (Experiment 1) or happiness or sadness (Experiment 2). In line with previous research, results indicated that intended emotions (anger and fear) were successfully induced in the respective conditions in Experiment 1. However, disgust and sadness were also induced while writing about an angry experience compared to a fearful experience. Similarly, although happiness and sadness were induced in the appropriate conditions, Experiment 2 indicated that writing about a sad experience also induced disgust, fear, and anger, compared to writing about a happy experience. Possible resolutions to avoid the limitations of the AEMT to induce specific discrete emotions are discussed.     

Recognition profile of emotions in natural and virtual faces

Background

Computer-generated virtual faces become increasingly realistic including the simulation of emotional expressions. These faces can be used as well-controlled, realistic and dynamic stimuli in emotion research. However, the validity of virtual facial expressions in comparison to natural emotion displays still needs to be shown for the different emotions and different age groups.

Methodology/Principal Findings

Thirty-two healthy volunteers between the age of 20 and 60 rated pictures of natural human faces and faces of virtual characters (avatars) with respect to the expressed emotions: happiness, sadness, anger, fear, disgust, and neutral. Results indicate that virtual emotions were recognized comparable to natural ones. Recognition differences in virtual and natural faces depended on specific emotions: whereas disgust was difficult to convey with the current avatar technology, virtual sadness and fear achieved better recognition results than natural faces. Furthermore, emotion recognition rates decreased for virtual but not natural faces in participants over the age of 40. This specific age effect suggests that media exposure has an influence on emotion recognition.

Conclusions/Significance

Virtual and natural facial displays of emotion may be equally effective. Improved technology (e.g. better modelling of the naso-labial area) may lead to even better results as compared to trained actors. Due to the ease with which virtual human faces can be animated and manipulated, validated artificial emotional expressions will be of major relevance in future research and therapeutic applications.     

Identifying Emotions on the Basis of Neural Activation

We attempt to determine the discriminability and organization of neural activation corresponding to the experience of specific emotions. Method actors were asked to self-induce nine emotional states (anger, disgust, envy, fear, happiness, lust, pride, sadness, and shame) while in an fMRI scanner. Using a Gaussian Naïve Bayes pooled variance classifier, we demonstrate the ability to identify specific emotions experienced by an individual at well over chance accuracy on the basis of: 1) neural activation of the same individual in other trials, 2) neural activation of other individuals who experienced similar trials, and 3) neural activation of the same individual to a qualitatively different type of emotion induction. Factor analysis identified valence, arousal, sociality, and lust as dimensions underlying the activation patterns. These results suggest a structure for neural representations of emotion and inform theories of emotional processing.     

Physiological Responses Induced by Emotion-Eliciting Films

Emotion-eliciting films are commonly used to evoke subjective emotional responses in experimental settings. The main aim of the present study was to investigate whether a set of film clips with discrete emotions were capable to elicit measurable objective physiological responses. The convergence between subjective and objective measures was evaluated. Finally, the effect of gender on emotional responses was investigated. A sample of 123 subjects participated in the study. Individuals were asked to view a set of emotional film clips capable to induce seven emotions: anger, fear, sadness, disgust, amusement, tenderness and neutral state. Skin conductance level (SCL), heart rate (HR) and subjective emotional responses were measured for each film clip. In comparison with neutral films, SCL was significantly increased after viewing fear films, and HR was also significantly incremented for anger and fear films. Physiological variations were associated with arousal measures indicating a convergence between subjective and objective reactions. Women appeared to display significantly greater SCL and HR responses for films inducing sadness. The findings suggest that physiological activation would be more easily induced by emotion-eliciting films that tap into emotions with higher subjective arousal such as anger and fear.     

Neuroticism modifies psychophysiological responses to fearful films

Background

Neuroticism is a personality component frequently found in anxious and depressive psychiatric disorders. The influence of neuroticism on negative emotions could be due to its action on stimuli related to fear and sadness, but this remains debated. Our goal was thus to better understand the impact of neuroticism through verbal and physiological assessment in response to stimuli inducing fear and sadness as compared to another negative emotion (disgust).

Methods

Fifteen low neurotic and 18 high neurotic subjects were assessed on an emotional attending task by using film excerpts inducing fear, disgust, and sadness. We recorded skin conductance response (SCR) and corrugator muscle activity (frowning) as indices of emotional expression.

Results

SCR was larger in high neurotic subjects than in low neurotics for fear relative to sadness and disgust. Moreover, corrugator activity and SCR were larger in high than in low neurotic subjects when fear was induced.

Conclusion

After decades of evidence that individuals higher in neuroticism experience more intense emotional reactions to even minor stressors, our results indicate that they show greater SCR and expressive reactivity specifically to stimuli evoking fear rather than to those inducing sadness or disgust. Fear processing seems mainly under the influence of neuroticism. This modulation of autonomic activity by neurotics in response to threat/fear may explain their increased vulnerability to anxious psychopathologies such as PTSD (post traumatic stress disorder).     

Neuroanatomical Correlates of Recognizing Face Expressions in Mild Stages of Alzheimer’s Disease

Early Alzheimer’s disease can involve social disinvestment, possibly as a consequence of impairment of nonverbal communication skills. This study explores whether patients with Alzheimer’s disease at the mild cognitive impairment or mild dementia stage have impaired recognition of emotions in facial expressions, and describes neuroanatomical correlates of emotion processing impairment. As part of the ongoing PACO study (personality, Alzheimer’s disease and behaviour), 39 patients with Alzheimer’s disease at the mild cognitive impairment or mild dementia stage and 39 matched controls completed tests involving discrimination of four basic emotions—happiness, fear, anger, and disgust—on photographs of faces. In patients, automatic volumetry of 83 brain regions was performed on structural magnetic resonance images using MAPER (multi-atlas propagation with enhanced registration). From the literature, we identified for each of the four basic emotions one brain region thought to be primarily associated with the function of recognizing that emotion. We hypothesized that the volume of each of these regions would be correlated with subjects’ performance in recognizing the associated emotion. Patients showed deficits of basic emotion recognition, and these impairments were correlated with the volumes of the expected regions of interest. Unexpectedly, most of these correlations were negative: better emotional facial recognition was associated with lower brain volume. In particular, recognition of fear was negatively correlated with the volume of amygdala, disgust with pallidum, and happiness with fusiform gyrus. Recognition impairment in mild stages of Alzheimer’s disease for a given emotion was thus associated with less visible atrophy of functionally responsible brain structures within the patient group. Possible explanations for this counterintuitive result include neuroinflammation, regional β-amyloid deposition, or transient overcompensation during early stages of Alzheimer’s disease.     

Basic emotions evoked by eugenol odor differ according to the dental experience. A neurovegetative analysis.

Subjective individual experiences seem to indicate that odors may form strong connections with memories, especially those charged with emotional significance. In the dental field, this could be the case with the odorant eugenol, responsible for the typical clinging odor impregnating the dental office. The odor of eugenol could evoke memories of unpleasant dental experiences and, therefore, negative feelings such as anxiety and fear, since eugenates (cements containing eugenol) are used in potentially painful restorative dentistry. This hypothesis was tested by evaluating the emotional impact of the odor of eugenol through autonomic nervous system (ANS) analysis. The simultaneous variations of six ANS parameters (two electrodermal, two thermovascular and two cardiorespiratory), induced by the inhalation of this odorant, were recorded on volunteer subjects. Vanillin (a pleasant odorant) and propionic acid (an unpleasant one) served as controls. After the experiment, subjects were asked to rate the pleasantness versus unpleasantness of each odorant on an 11-point hedonic scale. The patterns of autonomic responses, obtained for each odorant and each subject, were transcribed into one of the six basic emotions defined by Ekman et al. (happiness, surprise, sadness, fear, anger and disgust). Results were compared between two groups of subjects divided according to their dental experience (fearful and non-fearful dental care subjects) and showed significant differences only for eugenol. This odorant was rated as pleasant by non-fearful dental subjects but unpleasant by fearful dental subjects. The evoked autonomic responses were mainly associated with positive basic emotions (happiness and surprise) in non-fearful dental subjects and with negative basic emotions (fear, anger, disgust) in fearful dental subjects. These results suggest that eugenol can be responsible for different emotional states depending on the subjects' dental experience, which seems to confirm the potential role of odors as elicitors of emotional memories. This study also supports the possible influence of the ambient odor impregnating the dental office, strengthening a negative conditioning toward dental care in some anxious patients.     

Neural structures associated with recognition of facial expressions of basic emotions.

People with Huntington''s disease and people suffering from obsessive compulsive disorder show severe deficits in recognizing facial expressions of disgust, whereas people with lesions restricted to the amygdala are especially impaired in recognizing facial expressions of fear. This double dissociation implies that recognition of certain basic emotions may be associated with distinct and non-overlapping neural substrates. Some authors, however, emphasize the general importance of the ventral parts of the frontal cortex in emotion recognition, regardless of the emotion being recognized. In this study, we used functional magnetic resonance imaging to locate neural structures that are critical for recognition of facial expressions of basic emotions by investigating cerebral activation of six healthy adults performing a gender discrimination task on images of faces expressing disgust, fear and anger. Activation in response to these faces was compared with that for faces showing neutral expressions. Disgusted facial expressions activated the right putamen and the left insula cortex, whereas enhanced activity in the posterior part of the right gyrus cinguli and the medial temporal gyrus of the left hemisphere was observed during processing of angry faces. Fearful expressions activated the right fusiform gyrus and the left dorsolateral frontal cortex. For all three emotions investigated, we also found activation of the inferior part of the left frontal cortex (Brodmann area 47). These results support the hypotheses derived from neuropsychological findings, that (i) recognition of disgust, fear and anger is based on separate neural systems, and that (ii) the output of these systems converges on frontal regions for further information processing.     

What is emotion?

There is no consensus in the literature on a definition of emotion. The term is taken for granted in itself and, most often, emotion is defined with reference to a list: anger, disgust, fear, joy, sadness, and surprise. This article expands on a thesis that motivational states can be compared to each other by means of a common currency (Philos. Trans. Roy. Soc. Lond. 270 (1975) 265-293). I have previously argued that this common currency is pleasure. Such a conclusion is based not on introspective intuition, as with early pre-scientific psychology (), but on experimental methods. As a follow-up to a definition of consciousness (Neurosci. Biobehav. Rev. 20 (1996) 33-40) as a four-dimensional experience (quality, intensity, hedonicity, and duration), I propose here that emotion is any mental experience with high intensity and high hedonic content (pleasure/displeasure).     

Optimal Geometrical Set for Automated Marker Placement to Virtualized Real-Time Facial Emotions

In recent years, real-time face recognition has been a major topic of interest in developing intelligent human-machine interaction systems. Over the past several decades, researchers have proposed different algorithms for facial expression recognition, but there has been little focus on detection in real-time scenarios. The present work proposes a new algorithmic method of automated marker placement used to classify six facial expressions: happiness, sadness, anger, fear, disgust, and surprise. Emotional facial expressions were captured using a webcam, while the proposed algorithm placed a set of eight virtual markers on each subject’s face. Facial feature extraction methods, including marker distance (distance between each marker to the center of the face) and change in marker distance (change in distance between the original and new marker positions), were used to extract three statistical features (mean, variance, and root mean square) from the real-time video sequence. The initial position of each marker was subjected to the optical flow algorithm for marker tracking with each emotional facial expression. Finally, the extracted statistical features were mapped into corresponding emotional facial expressions using two simple non-linear classifiers, K-nearest neighbor and probabilistic neural network. The results indicate that the proposed automated marker placement algorithm effectively placed eight virtual markers on each subject’s face and gave a maximum mean emotion classification rate of 96.94% using the probabilistic neural network.     

The Emotional Lives of Companion Animals: Attachment and Subjective Claims by Owners of Cats and Dogs

There is a growing body of scientific evidence supporting the existence of emotions in nonhuman animals. Companion-animal owners show a strong connection and attachment to their animals and readily assign emotions to them. In this paper we present information on how the attachment level of companion-animal owners correlates with their attribution of emotions to their companion cat or dog and their attribution of mirrored emotions. The results of an online questionnaire, completed by 1,023 Dutch-speaking cat and/or dog owners (mainly in the Netherlands and Belgium), suggest that owners attribute several emotions to their pets. Respondents attributed all posited basic (anger, joy [happiness], fear, surprise, disgust, and sadness) and complex (shame, jealousy, disappointment, and compassion) emotions to their companion animals, with a general trend toward basic emotions (with the exception of sadness) being more commonly attributed than complex emotions. All pet owners showed strong attachment to their companion animal(s), with the degree of attachment (of both cat and dog owners) varying significantly with education level and gender. Owners who ascribed human characteristics to their dog or cat also scored higher on the Pet Bonding Scale (PBS). Finally, owners who found it pleasant to pet their dog or cat had a higher average PBS score than those who did not like to do so. The relationship between owners’ attributions of mirrored emotions and the degree of attachment to dogs was significant for all emotions, whilst for cats this relationship was significant only for joy, sadness, surprise, shame, disappointment, and compassion.     

A Bayesian Model of Category-Specific Emotional Brain Responses

Understanding emotion is critical for a science of healthy and disordered brain function, but the neurophysiological basis of emotional experience is still poorly understood. We analyzed human brain activity patterns from 148 studies of emotion categories (2159 total participants) using a novel hierarchical Bayesian model. The model allowed us to classify which of five categories—fear, anger, disgust, sadness, or happiness—is engaged by a study with 66% accuracy (43-86% across categories). Analyses of the activity patterns encoded in the model revealed that each emotion category is associated with unique, prototypical patterns of activity across multiple brain systems including the cortex, thalamus, amygdala, and other structures. The results indicate that emotion categories are not contained within any one region or system, but are represented as configurations across multiple brain networks. The model provides a precise summary of the prototypical patterns for each emotion category, and demonstrates that a sufficient characterization of emotion categories relies on (a) differential patterns of involvement in neocortical systems that differ between humans and other species, and (b) distinctive patterns of cortical-subcortical interactions. Thus, these findings are incompatible with several contemporary theories of emotion, including those that emphasize emotion-dedicated brain systems and those that propose emotion is localized primarily in subcortical activity. They are consistent with componential and constructionist views, which propose that emotions are differentiated by a combination of perceptual, mnemonic, prospective, and motivational elements. Such brain-based models of emotion provide a foundation for new translational and clinical approaches.     

Impaired Recognition of Facially Expressed Emotions in Different Groups of Patients with Sleep Disorders

IntroductionRecently it has been shown that acute sleep loss has a direct impact on emotional processing in healthy individuals. Here we studied the effect of chronically disturbed sleep on emotional processing by investigating two samples of patients with sleep disorders.Methods25 patients with psychophysiologic insomnia (23 women and 2 men, mean age: 51.6 SD; 10.9 years), 19 patients with sleep apnea syndrome (4 women and 15 men, mean age: 51.9; SD 11.1) and a control sample of 24 subjects with normal sleep (15women and 9 men, mean age 45.3; SD 8.8) completed a Facial Expressed Emotion Labelling (FEEL) task, requiring participants to categorize and rate the intensity of six emotional expression categories: anger, anxiety, fear, happiness, disgust and sadness. Differences in FEEL score and its subscales among the three samples were analysed using ANOVA with gender as a covariate.ResultsBoth patients with psychophysiologic insomnia and patients with sleep apnea showed significantly lower performance in the FEEL test as compared to the control group. Differences were seen in the scales happiness and sadness. Patient groups did not differ from each other.ConclusionBy demonstrating that previously known effects of acute sleep deprivation on emotional processing can be extended to persons experiencing chronically disturbed sleep, our data contribute to a deeper understanding of the relationship between sleep loss and emotions.