Exercise-induced inflammation alters the perception and visual exploration of emotional interactions.

Introduction: The study aimed to investigate whether an exercise-induced pro-inflammatory response alters the perception as well as visual exploration of emotional body language in social interactions. Methods: In a within-subject design, 19 male, healthy adults aged between 19 and 33 years performed a downhill run for 45 min at 70% of their VO2max on a treadmill to induce maximal myokine blood elevations, leading to a pro-inflammatory status. Two control conditions were selected: a control run with no decline and a rest condition without physical exercise. Blood samples were taken before (T0), directly after (T1), 3 h after (T3), and 24 h after (T24) each exercise for analyzing the inflammatory response. 3 h after exercise, participants observed point-light displays (PLDs) of human interactions portraying four emotions (happiness, affection, sadness, and anger). Participants categorized the emotional content, assessed the emotional intensity of the stimuli, and indicated their confidence in their ratings. Eye movements during the entire paradigm and self-reported current mood were also recorded. Results: The downhill exercise condition resulted in significant elevations of measured cytokines (IL6, CRP, MCP-1) and markers for muscle damage (Myoglobin) compared to the control running condition, indicating a pro-inflammatory state after the downhill run. Emotion recognition rates decreased significantly after the downhill run, whereas no such effect was observed after control running. Participants' sensitivity to emotion-specific cues also declined. However, the downhill run had no effect on the perceived emotional intensity or the subjective confidence in the given ratings. Visual scanning behavior was affected after the downhill run, with participants fixating more on sad stimuli, in contrast to the control conditions, where participants exhibited more fixations while observing happy stimuli. Conclusion: Our study demonstrates that inflammation, induced through a downhill running model, impairs perception and emotional recognition abilities. Specifically, inflammation leads to decreased recognition rates of emotional content of social interactions, attributable to diminished discrimination capabilities across all emotional categories. Additionally, we observed alterations in visual exploration behavior. This confirms that inflammation significantly affects an individual's responsiveness to social and affective stimuli.

Recognition of emotional body language from dyadic and monadic point-light displays in 5-year-old children and adults.

Most child studies on emotion perception used faces and speech as emotion stimuli, but little is known about children's perception of emotions conveyed by body movements, that is, emotional body language (EBL). This study aimed to investigate whether processing advantages for positive emotions in children and negative emotions in adults found in studies on emotional face and term perception also occur in EBL perception. We also aimed to uncover which specific movement features of EBL contribute to emotion perception from interactive dyads compared with noninteractive monads in children and adults. We asked 5-year-old children and adults to categorize happy and angry point-light displays (PLDs), presented as pairs (dyads) and single actors (monads), in a button-press task. By applying representational similarity analyses, we determined intra- and interpersonal movement features of the PLDs and their relation to the participants' emotional categorizations. Results showed significantly higher recognition of happy PLDs in 5-year-olds and of angry PLDs in adults in monads but not in dyads. In both age groups, emotion recognition depended significantly on kinematic and postural movement features such as limb contraction and vertical movement in monads and dyads, whereas in dyads recognition also relied on interpersonal proximity measures such as interpersonal distance. Thus, EBL processing in monads seems to undergo a similar developmental shift from a positivity bias to a negativity bias, as was previously found for emotional faces and terms. Despite these age-specific processing biases, children and adults seem to use similar movement features in EBL processing.

Decoding spatiotemporal features of emotional body language in social interactions.

How are emotions perceived through human body language in social interactions? This study used point-light displays of human interactions portraying emotional scenes (1) to examine quantitative intrapersonal kinematic and postural body configurations, (2) to calculate interaction-specific parameters of these interactions, and (3) to analyze how far both contribute to the perception of an emotion category (i.e. anger, sadness, happiness or affection) as well as to the perception of emotional valence. By using ANOVA and classification trees, we investigated emotion-specific differences in the calculated parameters. We further applied representational similarity analyses to determine how perceptual ratings relate to intra- and interpersonal features of the observed scene. Results showed that within an interaction, intrapersonal kinematic cues corresponded to emotion category ratings, whereas postural cues reflected valence ratings. Perception of emotion category was also driven by interpersonal orientation, proxemics, the time spent in the personal space of the counterpart, and the motion-energy balance between interacting people. Furthermore, motion-energy balance and orientation relate to valence ratings. Thus, features of emotional body language are connected with the emotional content of an observed scene and people make use of the observed emotionally expressive body language and interpersonal coordination to infer emotional content of interactions.

When the timing is right: The link between temporal coupling in dyadic interactions and emotion recognition.

Affective states can be understood as dynamic interpersonal processes developing over time and space. When we observe emotional interactions performed by other individuals, our visual system anticipates how the action will unfold. Thus, it has been proposed that the process of emotion perception is not only a simulative but also a predictive process - a phenomenon described as interpersonal predictive coding. The present study investigated whether the recognition of emotions from dyadic interactions depends on a fixed spatiotemporal coupling of the agents. We used an emotion recognition task to manipulate the actions of two interacting point-light figures by implementing different temporal offsets that delayed the onset of one of the agent's actions (+0 ms, +500 ms, +1000 ms or + 2000 ms). Participants had to determine both the subjective valence and the emotion category (happiness, anger, sadness, affection) of the interaction. Results showed that temporal decoupling had a critical effect on both emotion recognition and the subjective impression of valence intensity: Both measures decreased with increasing temporal offset. However, these effects were dependent on which emotion was displayed. Whereas affection and anger sequences were impacted by the temporal manipulation, happiness and sadness were not. To further investigate these effects, we conducted post-hoc exploratory analyses of interpersonal movement parameters. Our findings complement and extend previous evidence by showing that the complex, noncoincidental coordination of actions within dyadic interactions results in a meaningful movement pattern and might serve as a fundamental factor in both detecting and understanding complex actions during human interaction.

Effects of visual and visual-haptic perception of material rigidity on reaching and grasping in the course of development.

The development of material property perception for grasping objects is not well explored during early childhood. Therefore, we investigated infants', 3-year-old children's, and adults' unimanual grasping behavior and reaching kinematics for objects of different rigidity using a 3D motion capture system. In Experiment 1, 11-month-old infants and for purposes of comparison adults, and in Experiment 2, 3-year old children were encouraged to lift relatively heavy objects with one of two handles differing in rigidity after visual (Condition 1) and visual-haptic exploration (Condition 2). Experiment 1 revealed that 11-months-olds, after visual object exploration, showed no significant material preference, and thus did not consider the material to facilitate grasping. After visual-haptic object exploration and when grasping the contralateral handles, infants showed an unexpected preference for the soft handles, which were harder to use to lift the object. In contrast, adults generally grasped the rigid handle exploiting their knowledge about efficient and functional grasping in both conditions. Reaching kinematics were barely affected by rigidity, but rather by condition and age. Experiment 2 revealed that 3-year-olds no longer exhibit a preference for grasping soft handles, but still no adult-like preference for rigid handles in both conditions. This suggests that material rigidity plays a minor role in infants' grasping behavior when only visual material information is available. Also, 3-year-olds seem to be on an intermediate level in the development from (1) preferring the pleasant sensation of a soft fabric, to (2) preferring the efficient rigid handle.

End in view: Joint end-state comfort depends on gaze and extraversion.

This study investigated how humans adapt to a partner's movement in a joint pick-and-place task and examined the role of gaze behavior and personality traits in adapting to a partner. Two participants sitting side-by-side transported a cup from one end of a table to the other. The participant sitting on the left (the agent) moved the cup to an intermediate position from where the participant sitting on the right (the partner) transported it to a goal position with varying orientations. Hand, finger, cup movements and gaze behavior were recorded synchronously via motion tracking and portable eye tracking devices. Results showed interindividual differences in the extent of the agents' motor adaptation to the joint action goal, which were accompanied by differences in gaze patterns. The longer agents directed their gaze to a cue indicating the goal orientation, the more they adapted the rotation of the cup's handle when placing it at the intermediate position. Personality trait assessment showed that higher extraverted tendencies to strive for social potency went along with more adaptation to the joint goal. These results indicate that agents who consider their partner's end-state comfort use their gaze to gather more information about the joint action goal compared to agents who do not. Moreover, the disposition to enjoy leadership and make decisions in interpersonal situations seems to play a role in determining who adapts to a partner's task in joint action.

Does co-presence affect the way we perceive and respond to emotional interactions?

This study compared how two virtual display conditions of human body expressions influenced explicit and implicit dimensions of emotion perception and response behavior in women and men. Two avatars displayed emotional interactions (angry, sad, affectionate, happy) in a "pictorial" condition depicting the emotional interactive partners on a screen within a virtual environment and a "visual" condition allowing participants to share space with the avatars, thereby enhancing co-presence and agency. Subsequently to stimulus presentation, explicit valence perception and response tendency (i.e. the explicit tendency to avoid or approach the situation) were assessed on rating scales. Implicit responses, i.e. postural and autonomic responses towards the observed interactions were measured by means of postural displacement and changes in skin conductance. Results showed that self-reported presence differed between pictorial and visual conditions, however, it was not correlated with skin conductance responses. Valence perception was only marginally influenced by the virtual condition and not at all by explicit response behavior. There were gender-mediated effects on postural response tendencies as well as gender differences in explicit response behavior but not in valence perception. Exploratory analyses revealed a link between valence perception and preferred behavioral response in women but not in men. We conclude that the display condition seems to influence automatic motivational tendencies but not higher level cognitive evaluations. Moreover, intragroup differences in explicit and implicit response behavior highlight the importance of individual factors beyond gender.

Practice modality of motor sequences impacts the neural signature of motor imagery.

Motor imagery is conceptualized as an internal simulation that uses motor-related parts of the brain as its substrate. Many studies have investigated this sharing of common neural resources between the two modalities of motor imagery and motor execution. They have shown overlapping but not identical activation patterns that thereby result in a modality-specific neural signature. However, it is not clear how far this neural signature depends on whether the imagined action has previously been practiced physically or only imagined. The present study aims to disentangle whether the neural imprint of an imagined manual pointing sequence within cortical and subcortical motor areas is determined by the nature of this prior practice modality. Each participant practiced two sequences physically, practiced two other sequences mentally, and did a behavioural pre-test without any further practice on a third pair of sequences. After a two-week practice intervention, participants underwent fMRI scans while imagining all six sequences. Behavioural data demonstrated practice-related effects as well as very good compliance with instructions. Functional MRI data confirmed the previously known motor imagery network. Crucially, we found that mental and physical practice left a modality-specific footprint during mental motor imagery. In particular, activation within the right posterior cerebellum was stronger when the imagined sequence had previously been practiced physically. We conclude that cerebellar activity is shaped specifically by the nature of the prior practice modality.

Sensory features of mental images in the framework of human actions.

What determines the sensory impression of a self-generated motor image? Motor imagery is a process in which subjects imagine executing a body movement with a strong kinesthetic and/or visual component from a first-person perspective. Both sensory modalities can be combined flexibly to form a motor image. 90 participants of varying ages had to freely generate motor images from a large set of movements. They were asked to rate their kinesthetic as well as their visual impression, the perceived vividness, and their personal experience with the imagined movement. Data were subjected to correlational analyses, linear regressions, and representation similarity analyses. Results showed that both action characteristics and experience drove the sensory impression of motor images with a strong individual component. We conclude that imagining actions that impose varying demands can be considered as reexperiencing actions by using one's own sensorimotor representations that represent not only individual experience but also action demands.

Emotional expressivity of the observer mediates recognition of affective states from human body movements.

Research on human motion perception shows that people are highly adept at inferring emotional states from body movements. Yet, this process is mediated by a number of individual factors and experiences. Within this study, we tackle two questions. Firstly, we ask which part of the body transmits the key information that is used to infer affective states. Secondly, we address how the observer's own emotional expressivity influences the recognition process. We used two types of impoverished point-light displays depicting the same emotional interactions as either arm or trunk movements. Results showed that participants used different sources of information in an emotion-specific manner. Participants with richer self-reported emotional expressivity showed higher recognition accuracies overall but also benefited more from information delivered by arm gestures. We interpret our findings in terms of embodied simulation, suggesting that emotion perception constitutes a function of the expressing body and the individual observer.

Prediction of action outcome: Effects of available information about body structure.

Correctly perceiving the movements of opponents is essential in everyday life as well as in many sports. Several studies have shown a better prediction performance for detailed stimuli compared to point-light displays (PLDs). However, it remains unclear whether differences in prediction performance result from explicit information about articulation or from information about body shape. We therefore presented three different types of stimuli (PLDs, stick figures, and skinned avatars) with different amounts of available information of soccer players' run-ups. Stimulus presentation was faded out at ball contact. Participants had to react to the perceived shot direction with a full-body movement. Results showed no differences for time to virtual ball contact between presentation modes. However, prediction performance was significantly better for avatars and stick figures compared to PLDs, but did not differ between avatars and stick figures, suggesting that explicit information about the articulation of the major joints is mainly relevant for better prediction performance, and plays a larger role than detailed information about body shape. We also tracked eye movements and found that gaze behavior for avatars differed from those for PLDs and stick figures, with no significant differences between PLDs and stick figures. This effect was due to more and longer fixations on the head when avatars were presented.

Subjective vividness of motor imagery has a neural signature in human premotor and parietal cortex.

Motor imagery (MI) is the process in which subjects imagine executing a body movement with a strong kinesthetic component from a first-person perspective. The individual capacity to elicit such mental images is not universal but varies within and between subjects. Neuroimaging studies have shown that these inter-as well as intra-individual differences in imagery quality mediate the amplitude of neural activity during MI on a group level. However, these analyses were not sensitive to forms of representation that may not map onto a simple modulation of overall amplitude. Therefore, the present study asked how far the subjective impression of motor imagery vividness is reflected by a spatial neural code, and how patterns of neural activation in different motor regions relate to specific imagery impressions. During fMRI scanning, 20 volunteers imagined three different types of right-hand actions. After each imagery trial, subjects were asked to evaluate the perceived vividness of their imagery. A correlation analysis compared the rating differences and neural dissimilarity values of the rating groups separately for each region of interest. Results showed a significant positive correlation in the left vPMC and right IPL, indicating that these regions particularly reflect perceived imagery vividness in that similar rated trials evoke more similar neural patterns. A decoding analysis revealed that the vividness of the motor image related systematically to the action specificity of neural activation patterns in left vPMC and right SPL. Imagined actions accompanied by higher vividness ratings were significantly more distinguishable within these areas. Altogether, results showed that spatial patterns of neural activity within the human motor cortices reflect the individual vividness of imagined actions. Hence, the findings reveal a link between the subjective impression of motor imagery vividness and objective physiological markers.

Specificity of Postural Control: Comparing Expert and Intermediate Dancers.

The expert-novice approach is inappropriate for studying postural control in sport and dance when novices are completely unable to perform relevant postural tasks and experts cannot demonstrate specific skills on everyday postural tasks. We tested expertise-specific differences on 6 static everyday and 5 dynamic dance-like postural tasks of varying difficulty in 13 professional and 12 intermediate nonprofessional dancers. Results showed a clear expert advantage on sway area for dance-like postural tasks, but not for static everyday tasks. This effect was also found for the control parameter of root mean square (RMS) velocity and partly for RMS amplitude of the difference signal between CoP and CoG line location. Results indicate that the expert advantage is task-specific and deliver new insights into the specificity of experts' postural performance.

Neural Underpinnings of the Perception of Emotional States Derived From Biological Human Motion: A Review of Neuroimaging Research.

Research on the perception of biological human motion shows that people are able to infer emotional states by observing body movements. This article reviews the methodology applied in fMRI research on the neural representation of such emotion perception. Specifically, we ask how different stimulus qualities of bodily expressions, individual emotional valence, and task instructions may affect the neural representation of an emotional scene. The review demonstrates the involvement of a variety of brain areas, thereby indicating how well the human brain is adjusted to navigate in multiple social situations. All stimulus categories (i.e., full-light body displays, point-light displays, and avatars) can induce an emotional percept and are associated with increased activation in an extensive neural network. This network seems to be organized around areas belonging to the so-called action observation network (PMC, IFG, and IPL) and the mentalizing network (TPJ, TP, dmPFC, and lOFC) as well as areas processing body form and motion (e.g., EBA, FBA, and pSTS). Furthermore, emotion-processing brain sites such as the amygdala and the hypothalamus seem to play an important role during the observation of emotional body expressions. Whereas most brain regions clearly display an increased response to emotional body movements in general, some structures respond selectively to negative valence. Moreover, neural activation seems to depend on task characteristics, indicating that certain structures are activated even when attention is shifted away from emotional body movements.

Task-Specificity of Muscular Responses During Motor Imagery: Peripheral Physiological Effects and the Legacy of Edmund Jacobson.

Motor imagery has become a key issue in cognitive neuroscience and particularly in fMRI research. However, peripheral physiological effects of motor imagery were already being studied a century ago with some research hypotheses even tracing back to Washburn (1916). This review focuses on research by Edmund Jacobson in the early 1930s. Jacobsen demonstrated that peripheral physiological effects rely on task-specific instructions: Bending the right arm elicits muscular responses in the right biceps, but not in the muscles of other limbs. This review discusses how Jacobsen examined this issue in a series of studies. This scientific spadework is worth recalling here because of its methodological innovations and its forward-looking discussion that even today, continues to be relevant for prospective research on this topic.

How the Experimental Setting Influences Representativeness: A Review of Gaze Behavior in Football Penalty Takers.

This article reviews research on the gaze behavior of penalty takers in football. It focuses on how artificial versus representative experimental conditions affect gaze behavior in this far-aiming task. Findings reveal that-irrespective of the representativeness of the experimental conditions-different instructions regarding the aiming strategy and different threat conditions lead to different gaze patterns. Results also reveal that the goal size and the distance to the goal did not affect the gaze behavior. Moreover, it is particularly run-up conditions that lead to differences. These can be either artificial or more natural. During a natural run-up, penalty takers direct their gaze mainly toward the ball. When there is no run-up, they do not direct their gaze toward the ball. Hence, in order to deliver generalizable results with which to interpret gaze strategies, it seems important to use a run-up with a minimum length that is comparable to that in a real-life situation.

Gaze Behavior in a Natural Environment with a Task-Relevant Distractor: How the Presence of a Goalkeeper Distracts the Penalty Taker.

Gaze behavior in natural scenes has been shown to be influenced not only by top-down factors such as task demands and action goals but also by bottom-up factors such as stimulus salience and scene context. Whereas gaze behavior in the context of static pictures emphasizes spatial accuracy, gazing in natural scenes seems to rely more on where to direct the gaze involving both anticipative components and an evaluation of ongoing actions. Not much is known about gaze behavior in far-aiming tasks in which multiple task-relevant targets and distractors compete for the allocation of visual attention via gaze. In the present study, we examined gaze behavior in the far-aiming task of taking a soccer penalty. This task contains a proximal target, the ball; a distal target, an empty location within the goal; and a salient distractor, the goalkeeper. Our aim was to investigate where participants direct their gaze in a natural environment with multiple potential fixation targets that differ in task relevance and salience. Results showed that the early phase of the run-up seems to be driven by both the salience of the stimulus setting and the need to perform a spatial calibration of the environment. The late run-up, in contrast, seems to be controlled by attentional demands of the task with penalty takers having habitualized a visual routine that is not disrupted by external influences (e.g., the goalkeeper). In addition, when trying to shoot a ball as accurately as possible, penalty takers directed their gaze toward the ball in order to achieve optimal foot-ball contact. These results indicate that whether gaze is driven by salience of the stimulus setting or by attentional demands depends on the phase of the actual task.

Perceived Intensity of Emotional Point-Light Displays is Reduced in Subjects with ASD.

One major characteristic of autism spectrum disorder (ASD) is problems with social interaction and communication. The present study explored ASD-related alterations in perceiving emotions expressed via body movements. 16 participants with ASD and 16 healthy controls observed video scenes of human interactions conveyed by point-light displays. They rated the valence of the depicted emotions in terms of their intensity and judged their confidence in their ratings. Results showed that healthy participants rated emotional interactions displaying positive emotionality as being more intense and were more confident about their ratings than ASD subjects. Results support the idea that patients with ASD have an altered perception of emotions. This extends research on subjective features (intensity, confidence) of emotion perception to the domain of emotional body movements and kinematics.

Motion database of disguised and non-disguised team handball penalty throws by novice and expert performers.

This article describes the motion database for a large sample (n = 2400) of 7-m penalty throws in team handball that includes 1600 disguised throws. Throws were performed by both novice (n = 5) and expert (n = 5) penalty takers. The article reports the methods and materials used to capture the motion data. The database itself is accessible for download via JLU Web Server and provides all raw files in a three-dimensional motion data format (.c3d). Additional information is given on the marker placement of the penalty taker, goalkeeper, and ball together with details on the skill level and/or playing history of the expert group. The database was first used by Helm et al. (2017) [1] to investigate the kinematic patterns of disguised movements. Results of this analysis are reported and discussed in their article "Kinematic patterns underlying disguised movements: Spatial and temporal dissimilarity compared to genuine movement patterns" (doi:10.1016/j.humov.2017.05.010) [1].

Impact of task difficulty on gaze behavior in a sequential object manipulation task.

Task difficulty affects both gaze behavior and hand movements. Therefore, the present study aimed to investigate how task difficulty modulates gaze behaviour with respect to the balance between visually monitoring the ongoing action and prospectively collecting visual information about the future course of the ongoing action. For this, we examined sequences of reach and transport movements of water glasses that differed in task difficulty using glasses filled to different levels. Participants had to grasp water glasses with different filling levels (100, 94, 88, 82, and 76%) and transport them to a target. Subsequently, they had to grasp the next water glass and transport it to a target on the opposite side. Results showed significant differences in both gaze and movement kinematics for higher filling levels. However, there were no relevant differences between the 88, 82, and 76% filling levels. Results revealed a significant influence of task difficulty on the interaction between gaze and kinematics during transport and a strong influence of task difficulty on gaze during the release phase between different grasp-to-place movements. In summary, we found a movement and gaze pattern revealing an influence of task difficulty that was especially evident for the later phases of transport and release.