Single point motion kinematics convey emotional signals in children and adults.

This study investigates whether humans recognize different emotions conveyed only by the kinematics of a single moving geometrical shape and how this competence unfolds during development, from childhood to adulthood. To this aim, animations in which a shape moved according to happy, fearful, or neutral cartoons were shown, in a forced-choice paradigm, to 7- and 10-year-old children and adults. Accuracy and response times were recorded, and the movement of the mouse while the participants selected a response was tracked. Results showed that 10-year-old children and adults recognize happiness and fear when conveyed solely by different kinematics, with an advantage for fearful stimuli. Fearful stimuli were also accurately identified at 7-year-olds, together with neutral stimuli, while, at this age, the accuracy for happiness was not significantly different than chance. Overall, results demonstrates that emotions can be identified by a single point motion alone during both childhood and adulthood. Moreover, motion contributes in various measures to the comprehension of emotions, with fear recognized earlier in development and more readily even later on, when all emotions are accurately labeled.

Newborns' perception of approach and withdrawal from biological movement: A closeness story.

Since birth, infants discriminate the biological motion (BM) revealed by point-light displays (PLDs). To date, no studies have explored whether newborns differentiate BM that approaches rather than withdraws from them. Yet, approach and withdrawal are two fundamental motivations in the socio-emotional world, key to developing empathy and prosocial behavior. Through a looking-behavior paradigm, we demonstrated that a few hours after birth, a human figure approaching attracted more visual attention than a human figure receding, showing that newborns are attuned to PLDs of others moving toward rather than walking away from them. Further, a withdrawing body appears to be less attractive than withdrawing scrambled points. Altogether, these observations support the existence of an early predisposition toward social closeness that might have its roots in an evolutionary perspective.

Neural signatures to prosocial and antisocial interactions in young infants.

Preverbal infants appear to be more attracted by prosocial characters and events, as typically assessed using preferential looking times and manual choice. However, infants' neural correlates of observed prosocial and antisocial interactions are still scarce. Here, we familiarized 5-month-old (N = 24) infants with a prosocial and antisocial scene (i.e., a character either helping or hindering) and infants' Event-Related Potentials (ERP) were recorded in response to the presentation of short video clips of the prosocial and antisocial interaction. On a neural level, results revealed that infants could discriminate between helping and hindering events at an early stage of processing, as shown by a larger N290 response to the former compared to the latter. Further, while the Nc - typically indexing attentional processes - was larger for antisocial over prosocial events, the LPP, indexing cognitive evaluation of the stimuli, was larger for prosocial over antisocial actions. Finally, infants' higher scores on the effortful control temperamental subscale were related to infants' increased N290 neural sensitivity to antisocial scenes. Together, these findings provide new evidence of the time course of infants' ERP responses during the observation of helping and hindering interactions, which involves both attentional and socially relevant processes.

Ostracism modulates children's recognition of emotional facial expressions.

Ostracism has been shown to induce considerable physiological, behavioral and cognitive changes in adults. Previous research demonstrated its effects on children's cognitive and behavioral abilities, but less is known about its impact on their capacity to recognize subtle variations in social cues. The present study aimed at investigating whether social manipulations of inclusion and ostracism modulate emotion recognition abilities in children, and whether this modulation varies across childhood. To do so, 5- and 10-year-old children participated in a computer-based ball tossing game called Cyberball during which they were either included or ostracized. Then, they completed a facial emotion recognition task in which they were required to identify neutral facial expressions, or varying levels of intensity of angry and fearful facial expressions. Results indicated lower misidentification rates for children who were previously ostracized as compared to children who were previously included, both at 5 and 10 years of age. Moreover, when looking at children's accuracy and sensitivity to facial expressions, 5-year-olds' decoding abilities were affected by the social manipulation, while no difference between included and ostracized participants was observed for 10-year-olds. In particular, included and ostracized 10-year-old children as well as ostracized 5-year-olds showed higher accuracy and sensitivity for expressions of fear as compared to anger, while no such difference was observed for included 5-year-olds. Overall, the current study presents evidence that Cyberball-induced inclusion and ostracism modulate children's recognition of emotional faces.

Encoding interactive scripts at 10 months of age.

Understanding action-reaction associations that give origin to interactive scripts (e.g., give-and-take interactions) is essential for appreciating social exchanges. However, studies on infants' action understanding have mainly investigated the case of actions performed by individual agents. Moreover, although extensive literature has explored infants' comprehension of action-effect relationships in object functioning, no study has addressed whether it also plays a role when observing social interactions, an issue we addressed here. In a first study, 10-month-old infants observed short videos of dyadic exchanges. We investigated whether they were able to link specific human gestures directed toward another person to specific vocal reactions in the receiver. We used a double-habituation paradigm in which infants were sequentially habituated to two specific action-reaction associations. In the test phase, infants watched one of the two habituated (Familiar) videos, a video with a reversed action-reaction association (Violation), and a Novel video. Results showed that the infants looked longer at both the Novel and Violation test trials than at the Familiar test trials. In a control study, we show that these results could not be accounted for by associative learning; indeed, learning of the action-reaction association did not occur when the vocalization was not produced by the receiver but only contingent on the agent's action. Thus, we show that 10-month-old infants can encode specific social action-effect relationships during the observation of dyadic interactions and that the interactivity of the social context may be critical to shaping young infants' understanding of others' behaviors.

Learning and generalization of repetition-based rules in autism.

Rule Learning (RL) allows us to extract and generalize high-order rules from a sequence of elements. Despite the critical role of RL in the acquisition of linguistic and social abilities, no study has investigated RL processes in Autism Spectrum Disorder (ASD). Here, we investigated RL in high-functioning autistic adolescents with ASD, examining whether their ability to extract and generalize rules from a sequence of visual elements is affected by the social vs. non-social nature of the stimulus and by visual working memory (WM). Using a forced-choice paradigm, ASD adolescents and typically developing (TD) peers were tested for their ability to detect and generalize high-order, repetition-based rules from visual sequences of simple non-social stimuli (shapes), complex non-social stimuli (inverted faces), and social stimuli (upright face). Both ASD and TD adolescents were able to generalize the rule they had learned to new stimuli, and their ability was modulated by the social nature of the stimuli and the complexity of the rule. Moreover, an association between RL and WM was found in the ASD, but not TD group, suggesting that ASD might have used additional or alternative strategies that relied on visual WM resources.

Preverbal infants tune manual choices on subliminal affective information.

Human behaviour is often shaped by unconscious emotional cues. From early on, infants are able to process emotional signals even if presented subliminally; however, whether subliminal emotional expressions are capable to affect infants' behaviour remains unknown. The current study aimed to fill this gap, recording 8-10-month-old infants' looking time and manual choice toward two objects previously associated to subliminal emotional faces. Results demonstrated that infants' manual choice, but not looking time, was guided by the previously presented subliminal emotional signal, as infants preferred to choose the object associated to the happy face. Overall, our findings show that preverbal infants tune their behaviour based on affective information, which drives them towards or away from previous encounters, even outside conscious awareness.

Sequential learning of emotional faces is statistical at 12 months of age.

Infants are capable of extracting statistical regularities from continuous streams of elements, which helps them structuring their surrounding environment. The current study examines 12-month-olds' capacity to extract statistical information from a sequence of emotional faces. Using a familiarization procedure, infants were presented with videos of two actresses expressing the same facial emotion, and subsequently turning toward or away from each other. Videos displayed different emotions (i.e., anger, happiness, fear, sadness, surprise, amusement, disgust, and exasperation) and were organized sequentially, so that the transitional probabilities between videos were highly predictable in some cases, and less predictable in others. At test, infants discriminated highly predictable from low predictable transitional probabilities, suggesting that they extracted statistical regularities from the sequence of emotional faces. However, when examining the looking toward and the looking away conditions separately, infants showed evidence of statistical learning in the looking toward condition only. Together, these findings suggest that 12-month-old infants rely on statistical learning to segment a continuous sequence of emotional faces, although this ability can be modulated by the nature of the stimuli. The contribution of statistical learning to structure infants' social environment is discussed.

Decoding functional brain networks through graph measures in infancy: The case of emotional faces.

Graph measures represent an optimal way to investigate neural networks' organization, yet their application is still limited in developmental samples. To uncover the organization of 7-month-old infants' functional brain networks during an emotional perception task, we combined a decoding technique (i.e., Principal Component Regression) to graph metrics computation. Nodes' Within Module Degree Z Score (WMDZ) was computed as a measure of modular organization, and we decoded networks' functional organizations across EEG alpha and theta bands in response to static and dynamic facial expressions of emotions. We found that infants' brain topological activity differentiates between static and dynamic emotional faces due to the involvement of visual streams and sensorimotor areas, as often observed in adults. Moreover, network invariances point toward an already present rudimental network structure tuned to face processing already at 7-months of age. Overall, our results affirm the fruitfulness of the application of graph measures in developmental samples, due to their flexibility and the wealth of information they provide over infants' networks functional organization.

Newborns' early attuning to hand-to-mouth coordinated actions.

Already inside the womb, fetuses frequently bring their hands to the mouth, anticipating hand-to-mouth contact by opening the mouth. Here, we explored whether 2-day-old newborns discriminate between hand actions directed towards different targets of the face-that is, a thumb that reaches the mouth and a thumb that reaches the chin. Newborns looked longer towards the thumb-to-mouth compared to the thumb-to-chin action only in the presence, and not absence, of anticipatory mouth opening movements, preceding the thumb arrival. Overall, our results show that newborns are sensitive to hand-to-face coordinated actions, being capable to discriminate between body-related actions directed towards different targets of the face, but only when a salient visual cue that anticipates the target of the action is present. The role of newborns' sensorimotor experience with hand-to-mouth gestures in driving this capacity is discussed.

Sensorimotor Activity and Network Connectivity to Dynamic and Static Emotional Faces in 7-Month-Old Infants.

The present study investigated whether, as in adults, 7-month-old infants' sensorimotor brain areas are recruited in response to the observation of emotional facial expressions. Activity of the sensorimotor cortex, as indexed by µ rhythm suppression, was recorded using electroencephalography (EEG) while infants observed neutral, angry, and happy facial expressions either in a static (N = 19) or dynamic (N = 19) condition. Graph theory analysis was used to investigate to which extent neural activity was functionally localized in specific cortical areas. Happy facial expressions elicited greater sensorimotor activation compared to angry faces in the dynamic experimental condition, while no difference was found between the three expressions in the static condition. Results also revealed that happy but not angry nor neutral expressions elicited a significant right-lateralized activation in the dynamic condition. Furthermore, dynamic emotional faces generated more efficient processing as they elicited higher global efficiency and lower networks' diameter compared to static faces. Overall, current results suggest that, contrarily to neutral and angry faces, happy expressions elicit sensorimotor activity at 7 months and dynamic emotional faces are more efficiently processed by functional brain networks. Finally, current data provide evidence of the existence of a right-lateralized activity for the processing of happy facial expressions.

Past and present experiences with maternal touch affect infants' attention toward emotional faces.

Maternal touch is considered crucial in regulating infants' internal states when facing unknown or distressing situations. Here, we explored the effects of maternal touch on 7-month-old infants' preferences towards emotions. Infants' looking times were measured through a two-trial preferential looking paradigm, while infants observed dynamic videos of happy and angry facial expressions. During the observation, half of the infants received an affective touch (i.e., stroke), while the other half received a non-affective stimulation (i.e., fingertip squeeze) from their mother. Further, we assessed the frequency of maternal touch in the mother-infant dyad through The Parent-Infant Caregiving Touch Scale (PICTS). Our results have shown that infants' attention to angry and happy facial expressions varied as a function of both present and past experiences with maternal touch. Specifically, in the affective touch condition, as the frequency of previous maternal affective tactile care increased (PICTS), the avoidance of angry faces decreased. Conversely, in the non-affective touch condition, as the frequency of previous maternal affective tactile care increased (PICTS), the avoidance of angry faces increased as well. Thus, past experience with maternal affective touch is a crucial predictor of the regulatory effects that actual maternal touch exerts on infants' visual exploration of emotional stimuli.

Do infants represent human actions cross-modally? An ERP visual-auditory priming study.

Recent findings indicate that 7-months-old infants perceive and represent the sounds inherent to moving human bodies. However, it is not known whether infants integrate auditory and visual information in representations of specific human actions. To address this issue, we used ERPs to investigate infants' neural sensitivity to the correspondence between sounds and images of human actions. In a cross-modal priming paradigm, 7-months-olds were presented with the sounds generated by two types of human body movement, walking and handclapping, after watching the kinematics of those actions in either a congruent or incongruent manner. ERPs recorded from frontal, central and parietal electrodes in response to action sounds indicate that 7-months-old infants perceptually link the visual and auditory cues of human actions. However, at this age these percepts do not seem to be integrated in cognitive multimodal representations of human actions.

Neural time course of pain observation in infancy.

Perception of pain in others is of great evolutionary significance for the development of human empathy. However, infants' sensitivity to others' painful experiences has not been investigated so far. Here, we explored the neural time course of infants' processing of others' pain by measuring event-related brain potentials (ERPs) while 6-month-old infants observed a painful tactile stimulation directed towards the eye and a neutral tactile stimulation on the eyebrow. We analyzed both the Negative Central (Nc) and the later Late Positive Potential (LPP) ERP components, indexing respectively attention allocation and cognitive evaluation of perceptual stimuli. Results showed that observing painful touch elicits a mid-latency Nc (300-500 ms) over the right fronto-central site, which is greater in amplitude as compared to neutral touch. A divergent activity was also visible in the centro-parietal early (550-750 ms) and late (800-1000 ms) LPP, showing increased amplitudes in response to neutral compared to painful touch. The cognitive evaluation of painful stimuli, reflected by the LPP, might thus not be fully developed at 6 months of age, as adults typically show a larger LPP in response to painful as compared to neutral stimuli. Overall, infants show early attentional attuning to others' pain. This early sensitivity to others' painful tactile experiences might form a prerequisite for the development of human empathy.

Social context influences infants' ability to extract statistical information from a sequence of gestures.

Infants' social environment is rich of complex sequences of events and actions. This study investigates whether 12-month-old infants are able to learn statistical regularities from a sequence of human gestures and whether this ability is affected by a social vs non-social context. Using a visual familiarization task, infants were familiarized to a continuous sequence of eight videos in which two women imitated each other performing arm gestures. The sequence of videos in which the two women performed imitative gestures was organized into 4 different gesture units. Videos within a gesture unit had a highly predictable transitional probability, while such transition was less predictable between gesture units. The social context was manipulated varying the mutual gaze of the actors and their body orientation. At test, infants were able to discriminate between the high- and low-predictable gesture units in the social, but not in the non-social condition. Results demonstrate that infants are capable to detect statistical regularities from a sequence of human gestures performed by two different individuals. Moreover, our findings indicate that salient social cues can modulate infants' ability to extract statistical information from a sequence of gestures.

Emotional facial expressions affect visual rule learning in 7- to 8-month-old infants.

Rule learning (RL) is an implicit learning mechanism that allows infants to detect and generalize rule-like repetition-based patterns (such as ABB and ABA) from a sequence of elements. Increasing evidence shows that RL operates both in the auditory and the visual domain and is modulated by the perceptual expertise with the to-be-learned stimuli. Yet, whether infants' ability to detect a high-order rule from a sequence of stimuli is affected by affective information remains a largely unexplored issue. Using a visual habituation paradigm, we investigated whether the presence of emotional expressions with a positive and a negative value (i.e., happiness and anger) modulates 7- to 8-month-old infants' ability to learn a rule-like pattern from a sequence of faces of different identities. Results demonstrate that emotional facial expressions (either positive and negative) modulate infants' visual RL mechanism, even though positive and negative facial expressions affect infants' RL in a different manner: while anger disrupts infants' ability to learn the rule-like pattern from a face sequence, in the presence of a happy face infants show a familiarity preference, thus maintaining their learning ability. These findings show that emotional expressions exert an influence on infants' RL abilities, contributing to the investigation on how emotion and cognition interact in face processing during infancy.

Mirror-touch experiences in the infant brain.

Several adult studies have proved the existence of a shared neural circuit in the somatosensory cortices that responds to both the body being touched and the sight of the body being touched. Despite the fundamental role of touch in infancy, the existence of similar visuo-tactile mirroring processes, supporting both felt and seen touch, still needs an in-depth empirical investigation. To this aim, we explored 8-month-olds mu desynchronization over somatosensory sites in response to felt and observed touch in a live experimental setting. EEG desynchronization (6-8 Hz mu frequency range) was measured during three experimental conditions: i) infants were stroked on their right hand by a parent (Touch condition); ii) infants observed a right hand being stroked (Observation Touch condition); iii) infants observed a right hand moving over the left hand without making contact (Action Control condition). Mu desynchronization of somatosensory sites contralateral to the hand being stroked emerged in response to both Touch and Observation Touch conditions, but not in the Action control condition. Further, greater mu desynchronization was found in the Touch and Observation Touch conditions as compared to the Action control condition. Our results highlight the early involvement of a shared somatosensory system, likely supporting infants' understanding of others' tactile sensations.

Motor learning in unilateral cerebral palsy and the influence of corticospinal tract reorganization.

Cerebral Palsy (CP) is a complex neurological disorder, characterized by congenital motor disability associated with behaviour, perception and cognition disorders. The sensorimotor impairments represent the main hallmark of the disease, significantly impacting the quality of life. So far, few studies have investigated motor learning abilities in CP and their association with the plastic reorganization of the motor system remains largely unknown. The present proof-of-principle study explored explicit motor sequence learning in children with unilateral CP and different patterns of motor system reorganization (bilateral, ipsilateral, contralateral). Children with unilateral CP, and a group of age-matched typically developing (TD) children, underwent a sequential finger tapping task, performed with the affected hand by children with CP and with the non-dominant hand by TD children. The pattern of corticospinal tract projections in hemiparetic patients was assessed by single-pulse Transcranial Magnetic Stimulation (TMS). Results showed the presence of finger dexterity impairments in children with unilateral CP presenting with a bilateral or an ipsilateral control of the affected (trained) hand, as compared to TD children. Conversely, motor sequence learning was impaired in unilateral CP with ipsilateral or contralateral corticospinal reorganization, but not in the case of a bilateral control of the paretic hand. These preliminary findings, although referred to small clinical samples, suggest that unilateral control of the paretic upper-limb, from the ipsilateral or the contralateral motor cortex, may not be sufficient to develop typical motor learning with the affected hand, which seems to require a bilateral representation in the motor cortex. This evidence has potential implications for fine motor skills rehabilitation in CP.

Binding actions and emotions in the infant's brain.

The first year represents an exceptional time of development during which important social skills emerge, like action and emotion understanding. However, to date, no study explored the neural underpinnings of infants' ability to bind emotion- to action-related information. To assess this issue, we measured EEG activity while 6-month-old infants observed the same action performed by an actress displaying three different emotional expressions (happiness, anger and neutral). Results have shown that actions embedded in an emotional context (happiness and anger) elicited larger early negativity at parieto-occipital sites compared to a neutral context. This finding suggests that already at 6 months of age, infants use information coming from facial expressions to detect the saliency and relevance of others' actions.

Subliminal affective priming changes the 'feeling' towards neutral objects in infancy.

In everyday life, our preferences are governed by influences that we are frequently not aware of. Studies investigating visual subliminal priming have shown that emotions are particularly able to modulate the affective judgments both at a behavioural and neural level. In this study, we investigated whether emotional unconscious learning is a core feature of human development, by testing infants as young as 3 months of age on a subliminal affective priming task, in which infants were primed with subliminal happy and angry faces (Experiment 1) or subliminal neutral and scrambled faces (Experiment 2), followed by two neutral objects. We found that arousal to the neutral objects - as indexed through skin conductance - changed when they were primed with faces displaying emotional valence, and particularly anger, but not when the face had a neutral expression. This change in physiological state only partially corresponded to a change in explicit behaviour - as indexed through looking times - suggesting that emotional unconscious learning likely influences explicit behaviour at later stages of development, when subcortical-to-cortical connections have strengthened.