Neuroadaptive Bayesian optimisation to study individual differences in infants' engagement with social cues

Infants' motivation to engage with the social world depends on the interplay between individual brain's characteristics and previous exposure to social cues such as the parent's smile or eye contact. Different hypotheses about why specific combinations of emotional expressions and gaze direction engage children have been tested with group-level approaches rather than focusing on individual differences in the social brain development. Here, a novel Artificial Intelligence-enhanced brain-imaging approach, Neuroadaptive Bayesian Optimisation (NBO), was applied to infant electro-encephalography (EEG) to understand how selected neural signals encode social cues in individual infants. EEG data from 42 6- to 9-month-old infants looking at images of their parent's face were analysed in real-time and used by a Bayesian Optimisation algorithm to identify which combination of the parent's gaze/head direction and emotional expression produces the strongest brain activation in the child. This individualised approach supported the theory that the infant's brain is maximally engaged by communicative cues with a negative valence (angry faces with direct gaze). Infants attending preferentially to faces with direct gaze had increased positive affectivity and decreased negative affectivity. This work confirmed that infants' attentional preferences for social cues are heterogeneous and shows the NBO's potential to study diversity in neurodevelopmental trajectories.

Electrophysiological correlates of semantic pain processing in the affective priming

Introduction

Pain plays a fundamental role in the well-being of the individual, and its semantic content may have specific properties compared to other negative domains (i.e., fear and anger) which allows the cognitive system to detect it with priority. Considering the influence of the affective context in which stimuli (targets) are evaluated, it is possible that their valence could be differentially processed if preceded by negative stimuli (primes) associated with pain than negative stimuli not associated with pain. Thus, the present study aims to investigate the electrophysiological correlates of the implicit processing of words with pain content by using an affective priming paradigm.

Methods

Event-related potentials (ERPs) were recorded while participants were presented with positive and negative word targets (not associated with pain) that were preceded by positive, negative (not associated with pain), and pain word primes. Participants were asked to judge the valence of the target word.

Results

Results showed faster reaction times (RTs) in congruent conditions, especially when the negative target was preceded by a pain prime rather than a positive one. ERPs analyses showed no effect of pain at an early-stage processing (N400), but a larger waveform when the pain prime preceded the positive prime on the LPP.

Discussion

These results reaffirm the importance that valence has in establishing the priority with which stimuli are encoded in the environment and highlight the role that pain has in the processing of stimuli, supporting the hypothesis according to which the valence and the semantics of a stimulus interact with each other generating a specific response for each type of emotion.

Neural correlates of emotional valence for faces and words

Stimuli with negative emotional valence are especially apt to influence perception and action because of their crucial role in survival, a property that may not be precisely mirrored by positive emotional stimuli of equal intensity. The aim of this study was to identify the neural circuits differentially coding for positive and negative valence in the implicit processing of facial expressions and words, which are among the main ways human beings use to express emotions. Thirty-six healthy subjects took part in an event-related fMRI experiment. We used an implicit emotional processing task with the visual presentation of negative, positive, and neutral faces and words, as primary stimuli. Dynamic Causal Modeling (DCM) of the fMRI data was used to test effective brain connectivity within two different anatomo-functional models, for the processing of words and faces, respectively. In our models, the only areas showing a significant differential response to negative and positive valence across both face and word stimuli were early visual cortices, with faces eliciting stronger activations. For faces, DCM revealed that this effect was mediated by a facilitation of activity in the amygdala by positive faces and in the fusiform face area by negative faces; for words, the effect was mainly imputable to a facilitation of activity in the primary visual cortex by positive words. These findings support a role of early sensory cortices in discriminating the emotional valence of both faces and words, where the effect may be mediated chiefly by the subcortical/limbic visual route for faces, and rely more on the direct thalamic pathway to primary visual cortex for words.

Face Processing in Early Development: A Systematic Review of Behavioral Studies and Considerations in Times of COVID-19 Pandemic

Human faces are one of the most prominent stimuli in the visual environment of young infants and convey critical information for the development of social cognition. During the COVID-19 pandemic, mask wearing has become a common practice outside the home environment. With masks covering nose and mouth regions, the facial cues available to the infant are impoverished. The impact of these changes on development is unknown but is critical to debates around mask mandates in early childhood settings. As infants grow, they increasingly interact with a broader range of familiar and unfamiliar people outside the home; in these settings, mask wearing could possibly influence social development. In order to generate hypotheses about the effects of mask wearing on infant social development, in the present work, we systematically review N = 129 studies selected based on the most recent PRISMA guidelines providing a state-of-the-art framework of behavioral studies investigating face processing in early infancy. We focused on identifying sensitive periods during which being exposed to specific facial features or to the entire face configuration has been found to be important for the development of perceptive and socio-communicative skills. For perceptive skills, infants gradually learn to analyze the eyes or the gaze direction within the context of the entire face configuration. This contributes to identity recognition as well as emotional expression discrimination. For socio-communicative skills, direct gaze and emotional facial expressions are crucial for attention engagement while eye-gaze cuing is important for joint attention. Moreover, attention to the mouth is particularly relevant for speech learning. We discuss possible implications of the exposure to masked faces for developmental needs and functions. Providing groundwork for further research, we encourage the investigation of the consequences of mask wearing for infants' perceptive and socio-communicative development, suggesting new directions within the research field.

Prior sleep timing and visual recognition of emotional faces in 6-month-old infants

Face recognition is an important mnemonic ability for infants when navigating the social world. While age-related changes in face processing abilities are relatively well documented, less is known about short-term intra-individual fluctuations in this ability. Given that sleep deprivation in adults leads to impairments in information processing, we assessed the role of prior sleep on 6-month-old infants' (N = 17) visual recognition of faces showing three emotional expressions (neutral, sad, angry). Visual recognition was inferred by assessing novelty preferences for unfamiliar relative to familiarized faces in a visual recognition memory paradigm. In a within-subject design, infants participated once after they had recently woken up from a nap (nap condition) and once after they had been awake for an extended period of time (awake condition). Infants failed to show visual recognition for the neutral faces in either condition. Infants showed recognition for the sad and angry faces when tested in the awake condition, but not in the nap condition. This suggests that timing of prior sleep shapes how effectively infants process emotionally relevant information in their environment.

Individual Differences in Infants' Temperament Affect Face Processing

Infants show an advantage in processing female and familiar race faces, but the effect sizes are often small, suggesting individual differences in their discrimination abilities. This research assessed whether differences in 6-10-month-olds' temperament (surgency and orienting) predicted how they scanned individual faces varying in race and gender during familiarization and whether and how long it took them to locate the face during a visual search task. This study also examined whether infants viewing faces posing pleasant relative to neutral expressions would facilitate their discrimination of male and unfamiliar race faces. Results showed that infants' surgency on its own or in conjunction with their orienting regularly interacted with facial characteristics to predict their scanning and location of faces. Furthermore, infants' scanning patterns (dwell times and internal-external fixation shifts) correlated with their ability and time to locate a familiarized face. Moreover, infants who viewed faces with pleasant expressions showed better discrimination of unfamiliar race and male faces compared with infants who viewed neutral faces. Including temperament in the analyses consistently demonstrated its significance for understanding infant face processing. Findings suggest that positive interactions with other-race individuals and men might reduce processing disadvantages for those face types. Locating familiar adults in a timely manner is a crucial skill for infants to develop and these data elucidate factors influencing this ability.

The Role of Emotional Valence for the Processing of Facial and Verbal Stimuli-Positivity or Negativity Bias?

Emotional valence is predominately conveyed in social interactions by words and facial expressions. The existence of broad biases which favor more efficient processing of positive or negative emotions is still a controversial matter. While so far this question has been investigated separately for each modality, in this narrative review of the literature we focus on valence effects in processing both words and facial expressions. In order to identify the factors underlying positivity and negativity effects, and to uncover whether these effects depend on modality and age, we present and analyze three representative overviews of the literature concerning valence effects in word processing, face processing, and combinations of word and face processing. Our analysis of word processing studies points to a positivity bias or a balanced processing of positive and negative words, whereas the analysis of face processing studies showed the existence of separate positivity and negativity biases depending on the experimental paradigm. The mixed results seem to be a product of the different methods and types of stimuli being used. Interestingly, we found that children exhibit a clear positivity advantage for both word and face processing, indicating similar processing biases in both modalities. Over the course of development, the initial positivity advantage gradually disappears, and in some face processing studies even reverses into a negativity bias. We therefore conclude that there is a need for future research that systematically analyses the impact of age and modality on the emergence of these valence effects. Finally, we discuss possible explanations for the presence of the early positivity advantage and its subsequent decrease.

Processing of novel and familiar faces in infants at average and high risk for autism

The study investigated whether infant siblings of children with autism (sibs-ASD) process familiar and novel faces differently from typical infants and whether sensitivity to face familiarity is associated with infants' social and communicative behaviors. Visual event-related potentials (ERPs) were recorded in 35 infants, age 9 months ± 15 days (20 typical infants, 15 sibs-ASD) using an oddball paradigm presenting photographs of infants' mothers (70% of trials) and an unfamiliar female (30% of trials). Eye tracking responses to a different unfamiliar face were recorded to determine whether differences in gaze patterns might account for any ERP differences found. There were no group differences in the distribution, number or duration of fixations. Both infant groups differentiated between mothers and strangers, as reflected in amplitude modulations of posterior N290/P400 and frontal/central Nc responses. Group differences were present in the latency of the P400 response, where a delayed response to the stranger face was observed only in typical infants. Across both groups, shorter Nc latency to mother's face was associated with parental reports of stronger interpersonal skills. Individual differences in the speed of processing for novel vs. familiar faces may be an informative early marker of risk for atypical social development.

Faktoren der Gesichtserkennung im ersten Lebensjahr

Zusammenfassung. Schon gleich nach der Geburt bevorzugen es Säuglinge, Gesichter gegenüber anderen visuellen Objekten anzuschauen und lernen dann im Laufe des ersten Lebensjahres, immer mehr Gesichter zu unterscheiden und wiederzuerkennen. Es wird derzeit noch diskutiert, welche Faktoren für diese zunehmende Unterscheidungsleistung von Gesichtern verantwortlich sind. Ziel des vorliegenden Beitrags ist es darzulegen, welche Rolle die Faktoren – emotionaler Ausdruck von Gesichtern, Temperament und Kognition der Säuglinge sowie die Kultur – für eine solche Unterscheidungsleistung von Gesichtern innerhalb des ersten Lebensjahres spielen.