Psychophysiological responses to eye contact with a humanoid robot: Impact of perceived intentionality.

Eye contact with a social robot has been shown to elicit similar psychophysiological responses to eye contact with another human. However, it is becoming increasingly clear that the attention- and affect-related psychophysiological responses differentiate between direct (toward the observer) and averted gaze mainly when viewing embodied faces that are capable of social interaction, whereas pictorial or pre-recorded stimuli have no such capability. It has been suggested that genuine eye contact, as indicated by the differential psychophysiological responses to direct and averted gaze, requires a feeling of being watched by another mind. Therefore, we measured event-related potentials (N170 and frontal P300) with EEG, facial electromyography, skin conductance, and heart rate deceleration responses to seeing a humanoid robot's direct versus averted gaze, while manipulating the impression of the robot's intentionality. The results showed that the N170 and the facial zygomatic responses were greater to direct than to averted gaze of the robot, and independent of the robot's intentionality, whereas the frontal P300 responses were more positive to direct than to averted gaze only when the robot appeared intentional. The study provides further evidence that the gaze behavior of a social robot elicits attentional and affective responses and adds that the robot's seemingly autonomous social behavior plays an important role in eliciting higher-level socio-cognitive processing.

Being watched by a humanoid robot and a human: Effects on affect-related psychophysiological responses.

Eye contact with a humanoid robot has been shown to evoke similar affect and affiliation related psychophysiological responses as eye contact with another human. In this pre-registered study, we investigated whether these effects are dependent on the experience of being "watched". Psychophysiological responses (SCR, zygomatic and corrugator facial EMG, frontal EEG asymmetry) to a humanoid robot's or a human model's direct vs. averted gaze were measured while manipulating the participants' belief of whether the robot/human model could see them or not. The results showed greater autonomic arousal responses and facial responses related to positive affect both to the robot's and the human model's direct vs. averted gaze, regardless of the belief condition. The belief condition influenced the overall magnitude of these responses to both stimulus models, however, to a lesser extent for the robot than for the human model. For the frontal EEG asymmetry, the effect of gaze direction was non-significant in both belief conditions. The results lend further support for the importance of eye contact in human-robot interaction and provide insights into people's implicit attributions of humanoid robots' mental capacities.

Hormonal and behavioral responses to an infant simulator in women with and without children.

We investigated the impact of maternal status on hormonal reactivity and behavioral responses to an infant simulator in 117 women (54 primiparous, 63 nulliparous). The amount of affectionate touch and motherese were analyzed as behavioral measures of caregiving. Saliva was collected before and 10 min after interaction with the infant simulator to analyze oxytocin, testosterone, cortisol, and estradiol levels. Nulliparous women also provided information about their fertility motivation. Linear mixed models indicated that greater use of affectionate touch was associated with lower overall testosterone levels. Cortisol decreased in response to the interaction in both groups. In the primiparous group, the amount of affectionate touch associated inversely with cortisol levels, whereas in the nulliparous group such association was not found. Oxytocin or estradiol reactivity to the simulator did not differ between the groups, nor were these hormones associated with behavior. Higher fertility motivation in nulliparous women was related to more motherese, and lower testosterone levels. Our results indicate that the simulator elicits hormonal reactivity both in mothers and nonmothers, but the patterns of associations between caregiving behavior and hormonal levels may be partially different. These results encourage using the infant simulator to explore hormonal processes related to the transition to parenthood.

Neural specialization to human faces at the age of 7 months.

Sensitivity to human faces has been suggested to be an early emerging capacity that promotes social interaction. However, the developmental processes that lead to cortical specialization to faces has remained unclear. The current study investigated both cortical sensitivity and categorical specificity through event-related potentials (ERPs) previously implicated in face processing in 7-month-old infants (N290) and adults (N170). Using a category-specific repetition/adaptation paradigm, cortical specificity to human faces, or control stimuli (cat faces), was operationalized as changes in ERP amplitude between conditions where a face probe was alternated with categorically similar or dissimilar adaptors. In adults, increased N170 for human vs. cat faces and category-specific release from adaptation for face probes alternated with cat adaptors was found. In infants, a larger N290 was found for cat vs. human probes. Category-specific repetition effects were also found in infant N290 and the P1-N290 peak-to-peak response where latter indicated category-specific release from adaptation for human face probes resembling that found in adults. The results suggest cortical specificity to human faces during the first year of life. Encoding of unfamiliar cat stimuli might explain N290 amplification found in infants.

Effects of competition and bundled payment on the performance of hip replacement surgery in Stockholm, Sweden: results from a quasi-experimental study.

OBJECTIVE: To evaluate the effects of competition and a bundled payment model on the performance of hip replacement surgery. DESIGN: A quasi-experimental study where a difference-in-differences analytical framework is applied to analyse routinely collected patient-level data from multiple registers. SETTING: Hospitals providing hip replacement surgery in Sweden. PARTICIPANTS: The study included patients who underwent elective primary total hip replacement due to osteoarthritis from 2005 to 2012. The final study sample consisted of 85 275 hip replacement surgeries, where the exposure group consisted of 14 570 surgeries (n=6380 prereform and n=8190 postreform) and the control group consisted of 70 705 surgeries (n=32 799 prereform and n=37 906 postreform). INTERVENTION: A reform involving patient choice, free entry of new providers and a bundled payment model for hip replacement surgery, which came into force in 2009 in Region Stockholm, Sweden. OUTCOME MEASURES: Performance is measured as length of stay of the surgical admission, adverse event rate within 90 days following surgery and patient satisfaction 1 year postsurgery. RESULTS: The reform successfully improved the adverse event rate (1.6 percentage reduction, p<0.05). Length of stay decreased less in the more competitive market than in the control group (0.7 days lower, p<0.01). These effects were mainly driven by university and central hospitals. No effects of the reform on patient satisfaction were found (no significance). CONCLUSIONS: The study concludes that the incentives of the reform focusing on avoidance of adverse events have a predictable impact. Since the payment for providers is fixed per case, the impact on resource use is limited. Our findings contribute to the general knowledge about the effects of financial incentives and market-oriented reforms.

Processing children's faces in the parental brain: A meta-analysis of ERP studies.

Event-related potentials (ERPs) are an excellent tool for investigating parental neural responses to child stimuli. Using meta-analysis, we quantified the results of available studies reporting N170 or LPP/P3 ERP responses to children's faces, targeting three questions: 1) Do parents and non-parents differ in ERP responses to child faces? 2) Are parental ERP responses larger to own vs. unfamiliar child faces? 3) Are parental ERP responses to child faces associated with indicators of parenting quality, such as observed parental sensitivity? Across 23 studies (N = 1035), key findings showed 1) larger N170 amplitudes to child faces in parents than in non-parents (r = 0.19), 2) larger LPP/P3 responses to own vs. unfamiliar child faces in parents (r = 0.19), and 3) positive associations between parental LPP/P3 responses to child faces and parenting quality outcomes (r = 0.15). These results encourage further research particularly with the LPP/P3 to assess attentional-motivational processes of parenting, but also highlight the need for larger samples and more systematic assessments of associations between ERPs and parenting.

Attachment goes to court: child protection and custody issues.

Attachment theory and research are drawn upon in many applied settings, including family courts, but misunderstandings are widespread and sometimes result in misapplications. The aim of this consensus statement is, therefore, to enhance understanding, counter misinformation, and steer family-court utilisation of attachment theory in a supportive, evidence-based direction, especially with regard to child protection and child custody decision-making. The article is divided into two parts. In the first, we address problems related to the use of attachment theory and research in family courts, and discuss reasons for these problems. To this end, we examine family court applications of attachment theory in the current context of the best-interest-of-the-child standard, discuss misunderstandings regarding attachment theory, and identify factors that have hindered accurate implementation. In the second part, we provide recommendations for the application of attachment theory and research. To this end, we set out three attachment principles: the child's need for familiar, non-abusive caregivers; the value of continuity of good-enough care; and the benefits of networks of attachment relationships. We also discuss the suitability of assessments of attachment quality and caregiving behaviour to inform family court decision-making. We conclude that assessments of caregiver behaviour should take center stage. Although there is dissensus among us regarding the use of assessments of attachment quality to inform child custody and child-protection decisions, such assessments are currently most suitable for targeting and directing supportive interventions. Finally, we provide directions to guide future interdisciplinary research collaboration.

Signaled night awakening and its association with social information processing and socio-emotional development across the first two years.

STUDY OBJECTIVES: Night awakening is common in infancy, and some infants continue to have signaled night awakenings throughout early childhood. However, the influence of signaled night awakening on children's social development is less explored. In the present study, longitudinal associations between signaled night awakening, social information processing, and socio-emotional development were measured within the CHILD-SLEEP birth cohort in two groups formed based on parent-reported night awakenings. METHODS: At 8 months, there were 77 infants in the waking group (≥3 awakenings) and 69 infants in the nonwaking group (≤1 awakening). At 8 and 24 months, social information processing was measured as children's attention to neutral and emotional faces, and at 24 months, parent-reported socio-emotional behavior was measured with the Brief Infant-Toddler Social and Emotional Assessment (BITSEA) questionnaire. RESULTS: The two groups showed different patterns of attention to emotional faces. The waking group had a more pronounced attentional bias to fearful versus happy faces, whereas in the nonwaking group, attention to fearful and happy faces did not differ. In addition, at 24 months, the waking group had more dysregulation problems and lower social competence than the nonwaking group, but no clear differences in internalizing or externalizing problems were found. CONCLUSIONS: Our results contribute to the literature by showing that during the first 2 years of life, signaled night awakening is associated with social information processing and socio-emotional behavior.

Frontal EEG asymmetry in infants observing separation and comforting events: The role of infants' attachment relationship.

The development of social-cognitive abilities in infancy is subject to an intricate interaction between maturation of neural systems and environmental input. We investigated the role of infants' attachment relationship quality in shaping infants' neural responses to observed social interactions. One-hundred thirty 10-month-old infants participated in an EEG session while they watched animations involving a distressing separation event that ended with either comforting or ignoring behavior. Frontal asymmetry (FA) in the alpha range - which is indicative of approach-withdrawal tendencies - was measured with EEG. Attachment quality was assessed using the Strange Situation procedure at 12 months. Overall, infants with disorganized attachment showed a lack of right-sided - withdrawal related - FA compared to secure and insecure infants. Furthermore, only avoidant infants exhibited reduced right-sided FA responses following the separation. Contrary to our expectations, the type of response (comforting vs. ignoring) did not elicit differences in FA patterns, and attachment quality did not moderate the effects of the type of response on frontal asymmetry. Implications for research on attachment-related biases in social information processing and on the neural underpinnings of prosocial behaviors are discussed.

Making eye contact with a robot: Psychophysiological responses to eye contact with a human and with a humanoid robot.

Previous research has shown that eye contact, in human-human interaction, elicits increased affective and attention related psychophysiological responses. In the present study, we investigated whether eye contact with a humanoid robot would elicit these responses. Participants were facing a humanoid robot (NAO) or a human partner, both physically present and looking at or away from the participant. The results showed that both in human-robot and human-human condition, eye contact versus averted gaze elicited greater skin conductance responses indexing autonomic arousal, greater facial zygomatic muscle responses (and smaller corrugator responses) associated with positive affect, and greater heart deceleration responses indexing attention allocation. With regard to the skin conductance and zygomatic responses, the human model's gaze direction had a greater effect on the responses as compared to the robot's gaze direction. In conclusion, eye contact elicits automatic affective and attentional reactions both when shared with a humanoid robot and with another human.

Associations Between Neonatal Cry Acoustics and Visual Attention During the First Year.

It has been suggested that early cry parameters are connected to later cognitive abilities. The present study is the first to investigate whether the acoustic features of infant cry are associated with cognitive development already during the first year, as measured by oculomotor orienting and attention disengagement. Cry sounds for acoustic analyses (fundamental frequency; F0) were recorded in two neonatal cohorts at the age of 0-8 days (Tampere, Finland) or at 6 weeks (Cape Town, South Africa). Eye tracking was used to measure oculomotor orienting to peripheral visual stimuli and attention disengagement from central stimuli at 8 months (Tampere) or at 6 months (Cape Town) of age. Only a marginal positive correlation between fundamental frequency of cry (F0) and visual attention disengagement was observed in the Tampere cohort, but not in the Cape Town cohort. This correlation indicated that infants from the Tampere cohort with a higher neonatal F0 were marginally slower to shift their gaze away from the central stimulus to the peripheral stimulus. No associations between F0 and oculomotor orienting were observed in either cohort. We discuss possible factors influencing the current pattern of results suggesting a lack of replicable associations between neonatal cry and visual attention and suggest directions for future research investigating the potential of early cry analysis in predicting later cognitive development.

Psychophysiological responses to eye contact in a live interaction and in video call.

Another person's gaze directed to oneself elicits autonomic arousal and facial reactions indicating positive affect in its observer. These effects have only been found to occur with mutual, live eye contact and not in response to direct gaze pictures or when the observer believes that the live person cannot see them. The question remains whether the physical presence of the other person is necessary for these effects. We measured psychophysiological responses to another person's direct versus averted gaze in three conditions: live interaction, bidirectional video call, and watching a mere video. Autonomic arousal was measured with skin conductance responses and facial reactions with facial electromyography. In the live and video call conditions, but not in the mere video condition, direct gaze increased autonomic arousal in comparison to averted gaze. In all three conditions, however, direct gaze elicited positive affective facial reactions. Therefore, an experience of being seen is essential for the autonomic reactions but not for the facial responses that are elicited by another person's direct gaze. Most importantly, the results suggest that the physical presence or proximity of the other person is not necessary for these psychophysiological responses to eye contact.

Salivary cortisol reactivity to psychological stressors in infancy: A meta-analysis.

Measurement of salivary cortisol is a practical and non-invasive tool for studying stress reactivity to various types of stressors even in young infants. Whereas studies using physical stressors during the first months of life have found robust cortisol responses to painful stimuli, research with older infants using psychological stressors (e.g., parental separation) has produced mixed findings, limiting our understanding of potential developmental changes in cortisol reactivity across infancy. In the present study, we used meta-analysis to systematically investigate whether psychological stressor paradigms are associated with measurable cortisol responses in infants under 18 months of age and whether the magnitude of the responses is moderated by the type of psychological stressor (i.e., separation, frustration, novelty, or disruption of parental interaction), infant age, and other potential moderators. Across 47 studies (N = 4095, age range: 3-18 months), we found that commonly used psychological stressor paradigms are associated with a small (Hedges' g = .11) increase in salivary cortisol levels in typically developing infants. Stressor type moderated the effect sizes, and when effect sizes in each category were analyzed separately, only the separation studies were associated with a consistent increase in cortisol following the stressor. Age did not moderate the effect sizes either in the full set of studies or within the separate stressor types. These meta-analytic results indicate that the normative cortisol response to psychological stressors across infancy is small and emphasize the need for standardized stressor paradigms to assess cortisol responses systematically across infancy.

A performance comparison of patient pathways in Nordic capital areas - a pilot study for ischaemic stroke patients.

Aims: This article describes and discusses the extension of performance measurement using an episode-based approach so that the measurement includes primary care, and social and long-term-care services. By using data on incident stroke patients from the capital areas of four Nordic countries, this pilot study: (a) extended the disease-based performance analysis to include new indicators that better describe patient care pathways at different levels of care; (b) described and compared the performance of care given in the four areas; (c) evaluated how additional information changed the rankings of performance between the areas; and (d) described the trends in performance in the capital areas. Methods: The construction of data was based on a common protocol that used routinely collected national registers and statistics linked with local municipal registers. We created new variables describing the timing of discharge to home and institutionalisation, as well as describing the use and cost of primary and social hospital services. Risk adjustment was performed with four different sets of confounders. Results: Differences existed in various performance indicators between the four metropolitan areas. The ranking was sensitive to the risk-adjustment method. The study showed that for stroke patients a performance comparison with data that are only from secondary and tertiary care, and without a valid severity measure, is not sufficient for international comparisons. Conclusions: Extending and deepening international performance analysis in order to cover patient pathways, including primary care and social services, is very useful for benchmarking activities when focusing on diseases affecting older people.

Costs and Cost-Utility of Critical Care and Subsequent Health Care: A Multicenter Prospective Study.

OBJECTIVES: The number of critical care survivors is growing, but their long-term outcomes and resource use are poorly characterized. Estimating the cost-utility of critical care is necessary to ensure reasonable use of resources. The objective of this study was to analyze the long-term resource use and costs, and to estimate the cost-utility, of critical care. DESIGN: Prospective observational study. SETTING: Seventeen ICUs providing critical care to 85% of the Finnish adult population. PATIENTS: Adult patients admitted to any of 17 Finnish ICUs from September 2011 to February 2012, enrolled in the Finnish Acute Kidney Injury (FINNAKI) study, and matched hospitalized controls from the same time period. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We primarily assessed total 3-year healthcare costs per quality-adjusted life-years at 3 years. We also estimated predicted life-time quality-adjusted life-years and described resource use and costs. The costing year was 2016. Of 2,869 patients, 1,839 (64.1%) survived the 3-year follow-up period. During the first year, 1,290 of 2,212 (58.3%) index episode survivors were rehospitalized. Median (interquartile range) 3-year cumulative costs per patient were $49,200 ($30,000-$85,700). ICU costs constituted 21.4% of the total costs during the 3-year follow-up. Compared with matched hospital controls, costs of the critically ill remained higher throughout the follow-up. Estimated total mean (95% CI) 3-year costs per 3-year quality-adjusted life-years were $46,000 ($44,700-$48,500) and per predicted life-time quality-adjusted life-years $8,460 ($8,060-8,870). Three-year costs per 3-year quality-adjusted life-years were $61,100 ($57,900-$64,400) for those with an estimated risk of in-hospital death exceeding 15% (based on the Simplified Acute Physiology Score II). CONCLUSIONS: Healthcare resource use was substantial after critical care and remained higher compared with matched hospital controls. Estimated cost-utility of critical care in Finland was of high value.

Disorganized attachment representations, externalizing behavior problems, and socioemotional competences in early school-age.

Multifactorial research must examine if disorganized attachment is specifically associated with either ODD- or ADHD-symptoms,and the mechanisms through which disorganization may become associated with externalizing problems. The present short-term longitudinal study therefore examined attachment representations, and several competences important for socio-emotional functioning, in relation to ODD- and ADHD-symptoms at T1 (N = 105, M age = 80 months) and T2 (N = 80, M age = 104 months). There was a main effect of disorganized attachment on ODD-symptoms at both time points but not on ADHD-symptoms. Disorganized children also showed lowered attention to facial expressions, a diminished ability to discriminate facial expressions, and elevated emotional reactivity. Emotional reactivity mediated the link between disorganization and ODD-symptoms at T1, but not at T2. The findings support disorganized attachment as a risk-factor for ODD-symptoms rather than ADHD-symptoms, and suggest that disorganization may become associated with ODD-symptoms through broad effects on multiple competences.

Attachment security and cortical responses to fearful faces in infants.

The present study measured event-related potentials (ERPs) to investigate whether cortical responses to facial expressions of fear are associated with the development of secure and insecure patterns of infant-mother attachment during the first year. Based on previous findings showing reduced attentional biases to fearful faces in infants with insecure and disorganized attachment, we hypothesized that insecure and disorganized attachment would be associated with reduced ERP differentiation of fearful from non-fearful faces. ERPs to facial expressions were measured at 7 months of age and attachment was assessed at 14 months of age with the Strange Situation Procedure (n = 61). Occipitotemporal face-sensitive ERP responses particularly in the time range of the N290 component were related to attachment security at 14 months. Only securely attached infants showed age-typical cortical discrimination of fearful from non-fearful faces at 7 months, whereas a similar pattern of ERP responses was not observed in infants with insecure and disorganized attachment. These results add to previous findings by suggesting that patterns of secure and insecure infant attachment are related to early-emerging differences in the perceptual processing of facial emotions, which could have implications for the development of social competence.

Night Awakening and Its Association With Executive Functioning Across the First Two Years of Life.

Longitudinal associations between signaled night awakening and executive functioning (EF) at 8 and 24 months in children with (≥ 3 awakenings, n = 77) and without parent-rated fragmented sleep (≤ 1 awakening, n = 69) were studied. EF was assessed with the Switch task at 8 and 24 months. At 24 months, behavioral tasks and parental ratings of EF (Behavior Rating Inventory of Executive Function-Preschool version) were also used. In the Switch task, children with fragmented sleep were less able to learn stimulus sequences and inhibit previously learned responses than children without fragmented sleep. The groups differed only marginally in parental ratings of EF, and no differences were found in behavioral EF tasks. These results suggest that eye movement-based measures may reveal associations between sleep and EF already in infancy and toddlerhood.

The effect of being watched on facial EMG and autonomic activity in response to another individual's facial expressions.

We tested if facial reactions to another person's facial expressions depend on the self-relevance of the observed expressions. In the present study (n = 44), we measured facial electromyographic (zygomatic and corrugator) activity and autonomic arousal (skin conductance) responses to a live model's smiling and neutral faces. In one condition, the participant and the model were able to see each other normally, whereas in the other condition, the participant was led to believe that the model could not see the participant. The results showed that the increment of zygomatic activity in response to smiling faces versus neutral faces was greater when the participants believed they were being watched than it was when the participants believed they were not being watched. However, zygomatic responses to smiles did not differ between the conditions, while the results suggested that the participants' zygomatic responses to neutral faces seemed to attenuate in the condition of believing they were being watched. Autonomic responses to smiling faces were greater in the belief of being watched than in the belief of not being watched condition. The results suggest that the self-relevance of another individual's facial expression modulates autonomic arousal responses and to a lesser extent facial EMG responses.

Maternal and infant characteristics connected to shared pleasure in dyadic interaction.

The aim of the study was to analyze which maternal factors (depressive symptoms, effect of life events, maternal sensitivity and structuring) and infant characteristics (temperament, social withdrawal symptoms, interactive behavior, genotype, gender) contribute to shared pleasure (SP) in parent-infant interaction. Participants were 113 mother-infant dyads. The mothers filled in the Edinburgh Postnatal Depression Scale, the Infant Behavior Questionnaire, and the Life Events Questionnaire. The dyads were videotaped in a free-play situation, and the videos were analyzed using the Alarm Distress Baby Scale and the Emotional Availability Scales. The infants were genotyped for four genes involved in emotion regulation. The occurrence and duration of SP (SP-MD) in mother-infant interactions were analyzed from the videotapes. Higher maternal sensitivity and depressive symptoms, better infant responsiveness, and the infant having the GG variant of the gene tryptophan hydroxylase isoform 2 (TPH2) -307 were associated with the occurrence of SP. Lower level depressive symptoms, better maternal structuring, and greater infant involvement were associated with the longer duration of SP. Those dyads where the mother and infant were best able to read each other's positive cues and to respond to them were more likely to experience mutual positive affect, as seen in SP.

El propósito de este estudio fue analizar cuáles factores maternos (síntomas depresivos, efectos de eventos vividos, sensibilidad y estructuración maternas) y características del infante (temperamento, síntomas de despego social, comportamiento interactivo, genotipo, género sexual) contribuyen al placer compartido (SP) en la interacción progenitor-infante. En el estudio participaron 113 díadas madre-infante. Las madres completaron la Escala de Depresión Postnatal de Edimburgo, el Cuestionario de Comportamiento del Infante y el Cuestionario de Eventos de Vida. A las díadas se les grabó en video durante una sesión de juego libre y los videos se analizaron usando la Escala de Alarma de la Angustia del Bebé y las Escalas de Disponibilidad Emocional. A los infantes se les determinó el genotipo en el caso de cuatro genes que tienen que ver con la regulación emocional. Con base en las videograbaciones, se analizó la incidencia y duración de SP (SP-MD) en las interacciones madre-infante. Una más alta sensibilidad materna y síntomas depresivos, mejor sensibilidad por parte del infante, y el hecho de que el infante tenía la variante GG del gen TPH2 -307 se asociaron con la incidencia de SP. Síntomas depresivos de bajo nivel, una mejor estructuración materna y una mayor participación del infante se asociaron con una más larga duración de SP. Aquellas díadas en que la madre y el infante eran más capaces de comprender las señales positivas de cada uno y de responder a las mismas, estaban en mejor condición de experimentar un mutuo afecto positivo, como el que se ve en SP.

Le but de cette étude était d'analyser quels facteurs maternels (symptômes dépressifs, effet d'événements de la vie, sensibilité maternelle et structuration maternelle) et quelles caractéristiques du nourrisson (tempérament, symptômes de retrait social, comportement interactif, génotype, genre) contribuent au plaisir partagé (abrégé ici en français PP) dans l'interaction parent-nourrisson. Les participants ont consisté en 113 dyades mère-nourrisson. Les mères ont rempli l'Echelle de Dépression Postnatale d'Edinbourg, le Questionnaire du Comportement du Nourrisson, et le Questionnaire d'Evénements de la Vie. Les dyades ont été filmées à la vidéo pendant une situation de jeu libre et les vidéos ont été analysées en utilisant l'Echelle d'Alarme de Détresse du Bébé et les Echelles de Disponibilité Emotionnelle. Les nourrissons ont été génotypés pour quatre gènes impliqués dans la régulation de l'émotion. L'apparition et la durée du PP (en anglais SP-MD) dans les interactions mère-nourrisson ont été analysées à partir des vidéos. Une sensibilité maternelle plus élevée et des symptômes dépressifs, une meilleure réaction du nourrisson, le nourrisson ayant la variante GG du gène TPH2 -307 étaient liés à l'apparition du PP. Des niveaux plus bas de symptômes dépressifs, une meilleure structuration maternelle et un engagement plus important du nourrisson étaient liés à une durée plus longue du PP. Les dyades où la mère et le nourrisson étaient le plus capables de lire leurs signaux positifs réciproques et d'y répondre étaient moins à même de faire l'expérience d'une affect positif mutuel, comme on le voit dans le PP.