Multilevel analysis of facial expressions of emotion and script: self-report (arousal and valence) and psychophysiological correlates

Angry and fearful compared to happy or neutral faces as conditional stimuli in human fear conditioning: A systematic review and meta-analysis

Some previous research has shown stronger acquisition and impaired extinction of fear conditioned to angry or fearful compared to happy or neutral face conditional stimuli (CS) - a difference attributed to biological 'preparedness'. A systematic review and meta-analysis of fear conditioning studies comparing face CSs of differing expressions identified thirty studies, eighteen of which were eligible for meta-analysis. Skin conductance responses were larger to angry or fearful faces compared to happy or neutral faces during habituation, acquisition and extinction. Significant differences in differential conditioning between angry, fearful, neutral, and happy face CSs were also found, but differences were more prominent between angry and neutral faces compared to angry/fearful and happy faces. This is likely due to lower arousal elicited by neutral compared to happy faces, which may be more salient as CSs. The findings suggest there are small to moderate differences in differential conditioning when angry or fearful compared to happy or neutral faces are used as CSs. These findings have implications for fear conditioning study design and the preparedness theory.

Autonomic Nervous System Activity During Positive Emotions: A Meta-Analytic Review

Autonomic nervous system (ANS) activity is a fundamental component of emotional responding. It is not clear, however, whether positive emotional states are associated with differential ANS reactivity. To address this issue, we conducted a meta-analytic review of 120 articles (686 effect sizes, total N = 6,546), measuring ANS activity during 11 elicited positive emotions, namely amusement, attachment love, awe, contentment, craving, excitement, gratitude, joy, nurturant love, pride, and sexual desire. We identified a widely dispersed collection of studies. Univariate results indicated that positive emotions produce no or weak and highly variable increases in ANS reactivity. However, the limitations of work to date – which we discuss – mean that our conclusions should be treated as empirically grounded hypotheses that future research should validate.

Source memory and social exchange in young children

Reciprocal interactions require memories of social exchanges; however, little is known about how we remember social partner actions, especially during childhood when we start forming peer-to-peer relationships. This study examined if the expectation-violation effect, which has been observed in adults' source memory, exists among 5-6-year-old children. Forty participants played a coin collection game where they either received or lost coins after being shown an individual with a smiling or angry expression. This set-up generated congruent (smiling-giver and angry-taker) versus incongruent (smiling-taker and angry-giver) conditions. In the subsequent tasks, the children were asked to recall which actions accompanied each individual. The children considered the person with incongruent conditions as being stranger than the person with congruent conditions, suggesting that the former violated the children's emotion-based expectations. However, no heightened source memory was found for the incongruent condition. Instead, children seem to better recognise the action of angry individuals than smiling individuals, suggesting that angry facial expressions are more salient for children's source memory in a social exchange.

Use of fluorescent-labelled nanoplastics (NPs) to demonstrate NP absorption is inconclusive without adequate controls

Whether nanoplastics (NPs) are able to be absorbed across epithelial membranes and accumulate within internal tissues of organisms is an important determinant of their potential toxicity. Evidence of absorption and accumulation requires detection of NPs within internal tissues, and investigations with fluorescently labelled NPs have attempted to provide this information. We hypothesize that studies that do not control for the fluorescent dye leachate and/or cellular autofluorescence are inconclusive and can be misinterpreted. Our goal was to analyse previous investigations critically and conduct further research to determine if fluorescent-labelled polystyrene NPs (nanoPS) can provide conclusive evidence of absorption and internal accumulation of NPs. We exposed zebrafish embryos and larvae to NPs (500 and 1000 nm) labelled with a green or an orange fluorescent dye, to solutions resulting from nanoPS dialysis, and to Nile-Red (a fluorescent dye used as a positive control). Previous studies have claimed that NPs cross epithelia without accounting for dye leachates and/or cellular autofluorescence. Our results demonstrate that commercial fluorescent-labelled nanoPS can leach their fluorophores, and the fluorophore alone can accumulate within internal tissues of zebrafish larvae. We further observed green autofluorescence in fish larvae not exposed to any particles. Previous claims of NP absorption based on observations of fluorescence in zebrafish tissues should thus be considered inconclusive. Although the addition of purification steps and inclusion of controls for leaching of dyes are methodological improvements, the use of fluorescent nanoPS should not be considered to provide absolute conclusive evidence of particle absorption.

Subjective emotional arousal: an explorative study on the role of gender, age, intensity, emotion regulation difficulties, depression and anxiety symptoms, and meta-emotion

Subjective emotional arousal in typically developing adults was investigated in an explorative study. 177 participants (20-70 years) rated facial expressions and words for self-experienced arousal and perceived intensity, and completed the Difficulties in Emotion Regulation scale and the Hospital Anxiety and Depression scale (HADS-D). Exclusion criteria were psychiatric or neurological diseases, or clinically relevant scores in the HADS-D. Arousal regarding faces and words was significantly predicted by emotional clarity. Separate analyses showed following significant results: arousal regarding faces and arousal regarding words constantly predicted each other; negative faces were predicted by age and intensity; neutral faces by gender and impulse control; positive faces by gender and intensity; negative words by emotional clarity; and neutral words by gender. Males showed higher arousal scores than females regarding neutral faces and neutral words; for the other arousal scores, no explicit group differences were shown. Cluster analysis yielded three distinguished emotional characteristics groups: "emotional difficulties disposition group" (mainly females; highest emotion regulation difficulties, depression and anxiety scores; by trend highest arousal), "low emotional awareness group" (exclusively males; lowest awareness regarding currently experienced emotions; by trend intermediate arousal), and a "low emotional difficulties group" (exclusively females; lowest values throughout). No age effect was shown. Results suggest that arousal elicited by facial expressions and words are specialized parts of a greater emotional processing system and that typically developing adults show some kind of stable, modality-unspecific dispositional baseline of emotional arousal. Emotional awareness and clarity, and impulse control probably are trait aspects of emotion regulation that influence emotional arousal in typically developing adults and can be regarded as aspects of meta-emotion. Different emotional personality styles were shown between as well as within gender groups.

Empathy in Facial Mimicry of Fear and Disgust: Simultaneous EMG-fMRI Recordings During Observation of Static and Dynamic Facial Expressions

Real-life faces are dynamic by nature, particularly when expressing emotion. Increasing evidence suggests that the perception of dynamic displays enhances facial mimicry and induces activation in widespread brain structures considered to be part of the mirror neuron system, a neuronal network linked to empathy. The present study is the first to investigate the relations among facial muscle responses, brain activity, and empathy traits while participants observed static and dynamic (videos) facial expressions of fear and disgust. During display presentation, blood-oxygen level-dependent (BOLD) signal as well as muscle reactions of the corrugator supercilii and levator labii were recorded simultaneously from 46 healthy individuals (21 females). It was shown that both fear and disgust faces caused activity in the corrugator supercilii muscle, while perception of disgust produced facial activity additionally in the levator labii muscle, supporting a specific pattern of facial mimicry for these emotions. Moreover, individuals with higher, compared to individuals with lower, empathy traits showed greater activity in the corrugator supercilii and levator labii muscles; however, these responses were not differentiable between static and dynamic mode. Conversely, neuroimaging data revealed motion and emotional-related brain structures in response to dynamic rather than static stimuli among high empathy individuals. In line with this, there was a correlation between electromyography (EMG) responses and brain activity suggesting that the Mirror Neuron System, the anterior insula and the amygdala might constitute the neural correlates of automatic facial mimicry for fear and disgust. These results revealed that the dynamic property of (emotional) stimuli facilitates the emotional-related processing of facial expressions, especially among whose with high trait empathy.

Positive emotions have a unique capacity to capture attention

Most of the previous research in the area of cognitive psychology or cognitive neuroscience focused on studying negative emotions and argued that the negative emotional stimuli capture attention involuntarily as compared to neutral stimuli. However, in the last decades, researchers started paying attention in studying positive emotions also as positive emotions have evolutionary significance and are essential for many aspects of our life. The theme of this chapter is to present an overview of research in the area of positive emotions, and make a case that positively-valenced stimulus is prioritized over others. Primarily, when attentional resources are not constrained, many studies have shown that similar to negative stimuli, positive stimuli also capture attention automatically irrespective of whether they are relevant or irrelevant to the primary task. It suggests a fundamental prioritization of these stimuli by the cognitive/motivational system. However, when attentional resources are constrained, only positive or high rewarding stimuli win the competition for attentional resources compared to negative or stimuli associated with high punishment. Positive or high rewarding stimuli also receive priority in temporal selection, when attention is constrained. Theoretical implications of these results have been discussed. Possible cognitive and neural mechanisms have been proposed underlying these effects.

Valence, arousal or both? Shared emotional deficits associated with Attention Deficit and Hyperactivity Disorder and Oppositional/Defiant-Conduct Disorder symptoms in school-aged youth

We examined emotional responses in Attention Deficit Hyperactivity and Oppositional Defiant/Conduct Disorder to affective pictures. Eighty seven children (42 female, M_age = 11.2), with clinical or subclinical symptoms and controls viewed joy, fear, sadness or neutral pictures while heart rate, skin conductance, corrugator and zygomaticus responses were recorded. The moderating role of Callous-Unemotional and anxiety traits was evaluated. Lower resting heart rate and decreased skin conductance across picture types was associated with ADHD symptoms. Decreased heart rate reactivity to fear and sad stimuli was associated with ADHD and ODD/CD. Corrugator and zygomaticus responses were not associated with ADHD or ODD/CD. Findings are mostly consistent with a fearlessness account of disruptive behavior, and seem to also pertain to ADHD, with intact valence systems. Findings are discussed in light of the significance of identifying common pathogenic mechanisms across traditional diagnostic categories, consistent with trans-diagnostic approaches to the study of psychopathology.

Emotional Empathy and Facial Mimicry for Static and Dynamic Facial Expressions of Fear and Disgust

Facial mimicry is the tendency to imitate the emotional facial expressions of others. Increasing evidence suggests that the perception of dynamic displays leads to enhanced facial mimicry, especially for happiness and anger. However, little is known about the impact of dynamic stimuli on facial mimicry for fear and disgust. To investigate this issue, facial EMG responses were recorded in the corrugator supercilii, levator labii, and lateral frontalis muscles, while participants viewed static (photos) and dynamic (videos) facial emotional expressions. Moreover, we tested whether emotional empathy modulated facial mimicry for emotional facial expressions. In accordance with our predictions, the highly empathic group responded with larger activity in the corrugator supercilii and levator labii muscles. Moreover, dynamic compared to static facial expressions of fear revealed enhanced mimicry in the high-empathic group in the frontalis and corrugator supercilii muscles. In the low-empathic group the facial reactions were not differentiated between fear and disgust for both dynamic and static facial expressions. We conclude that highly empathic subjects are more sensitive in their facial reactions to the facial expressions of fear and disgust compared to low empathetic counterparts. Our data confirms that personal characteristics, i.e., empathy traits as well as modality of the presented stimuli, modulate the strength of facial mimicry. In addition, measures of EMG activity of the levator labii and frontalis muscles may be a useful index of empathic responses of fear and disgust.

Not knowing what I feel: Emotional empathy in autism spectrum disorders

While there is a general consensus in the literature that individuals with autism spectrum disorder have difficulty with cognitive empathy, much less is known about emotional empathy processing in these individuals. Most research has employed subjective self-report measures, which can often be misinterpreted or under-reported/over-reported. More objective measures such as psychophysiological recordings of arousal offer a more objective response. Furthermore, combining physiological responses with self-report ratings allows us to explore the relationship between these two responses to emotionally charged stimuli. A total of 25 individuals with autism spectrum disorder were compared with 25 matched controls on their physiological (arousal) and psychological (self-report) responses to emotionally distressing video scenes. These responses were also then compared with self-report cognitive and emotional trait empathy. Results indicate that while individuals with autism spectrum disorder appear to respond similarly to controls physiologically, their interpretation of this response is dampened emotionally. Furthermore, this dampening of self-report emotional response is associated with a general reduction in trait empathy.

Tuning to the Positive: Age-Related Differences in Subjective Perception of Facial Emotion

Facial expressions aid social transactions and serve as socialization tools, with smiles signaling approval and reward, and angry faces signaling disapproval and punishment. The present study examined whether the subjective experience of positive vs. negative facial expressions differs between children and adults. Specifically, we examined age-related differences in biases toward happy and angry facial expressions. Young children (5–7 years) and young adults (18–29 years) rated the intensity of happy and angry expressions as well as levels of experienced arousal. Results showed that young children—but not young adults—rated happy facial expressions as both more intense and arousing than angry faces. This finding, which we replicated in two independent samples, was not due to differences in the ability to identify facial expressions, and suggests that children are more tuned to information in positive expressions. Together these studies provide evidence that children see unambiguous adult emotional expressions through rose-colored glasses, and suggest that what is emotionally relevant can shift with development.