Using Infrared Thermography to Assess Emotional Responses to Infants

Facial thermal response to non-painful stressor in premature and term neonates

BACKGROUND

This study is a preliminary clinical investigation with the objective to evaluate the facial thermal response of premature and term neonates to a non-painful stressor (hunger) using infrared thermography (IRT). The development of objective and reliable parameters to monitor pain and stress is of relevance for optimal neonatal outcome and achieving a better management of patient comfort.

METHODS

We enrolled 12 neonates ranging from 27 to 39 weeks gestation (median: 34) and aged 3-79 days (median: 13). Recordings were performed before and after feeding, with and without hunger. Six regions of interest were chosen for evaluation (nose tip, periorbital and corrugator region, forehead, perioral and chin region).

RESULTS

There was an increase in the facial temperature in infants immediately prior to their next feed relative to infants who were not hungry, with the nasal tip being the facial evaluation site with the greatest temperature change.

CONCLUSIONS

The IRT appears to be a feasible and suitable method to detect changes in the neonatal patient. The thermal variations observed seem to reflect an arousal mediated by the parasympathetic nervous system, which has been described in existing infant stress research.

IMPACT

This is the first study to examine the use of infrared thermography (IRT) in monitoring the facial thermal response to a mild stressor (hunger) in premature and term neonates. Hunger as a mild, non-pain-associated stressor showed a significant effect on the facial temperature. The thermal signature of the regions of interest chosen showed hunger-related thermal variations. Results suggest the feasibility and suitability of IRT as an objective diagnostic tool to approach stress and changes in the condition of the neonatal patient.

That brachycephalic look: Infant-like facial appearance in short-muzzled dog breeds

Brachycephalic dog breeds are highly popular, yet their conformation-related disorders represent a major welfare concern. It has been suggested that the current popularity of such breeds can be explained by their cute, infant-like facial appearances. The concept of 'kindchenschema' refers to the observation that certain physical features of infant humans and other animals can automatically stimulate positive and nurturant feelings in adult observers. But the proposal that brachycephalic dogs possess heightened 'kindchenschema' facial features, even into adulthood, has never been formally investigated. Here, we hypothesised that relative muzzle shortening across a range of breeds would be associated with known 'kindchenschema' facial features, including a relatively larger forehead, larger eyes and smaller nose. Relative fronto-facial feature sizes in exemplar photographs of adult dogs from 42 popular breeds were measured and associated with existing data on the relative muzzle length and height-at-withers of the same breeds. Our results show that, in adulthood, shorter-muzzled breeds have relatively larger (taller) foreheads and relatively larger eyes (i.e. area of exposed eyeball relative to overall face area) than longer-muzzled breeds, and that this effect is independent of breed size. In sum, brachycephalic dog breeds do show exaggeration of some, but not all, known fronto-facial 'kindchenschema' features, and this may well contribute to their apparently cute appearance and to their current popularity as companion animals. We conclude that the challenge of addressing conformation-related disorders in companion dogs needs to take account of the cute, 'kindchenschema' looks that many owners are likely to be attracted to.

Facial temperature and pupil size as indicators of internal state in primates

Studies in human subjects have revealed that autonomic responses provide objective and biologically relevant information about cognitive and affective states. Measures of autonomic responses can also be applied to studies of non-human primates, which are neuro-anatomically and physically similar to humans. Facial temperature and pupil size are measured remotely and can be applied to physiological experiments in primates, preferably in a head-fixed condition. However, detailed guidelines for the use of these measures in non-human primates is lacking. Here, we review the neuronal circuits and methodological considerations necessary for measuring and analyzing facial temperature and pupil size in non-human primates. Previous studies have shown that the modulation of these measures primarily reflects sympathetic reactions to cognitive and emotional processes, including alertness, attention, and mental effort, over different time scales. Integrated analyses of autonomic, behavioral, and neurophysiological data in primates are promising methods that reflect multiple dimensions of emotion and could potentially provide tools for understanding the mechanisms underlying neuropsychiatric disorders and vulnerabilities characterized by cognitive and affective disturbances.

The neuroscience of social feelings: mechanisms of adaptive social functioning

Social feelings have conceptual and empirical connections with affect and emotion. In this review, we discuss how they relate to cognition, emotion, behavior and well-being. We examine the functional neuroanatomy and neurobiology of social feelings and their role in adaptive social functioning. Existing neuroscience literature is reviewed to identify concepts, methods and challenges that might be addressed by social feelings research. Specific topic areas highlight the influence and modulation of social feelings on interpersonal affiliation, parent-child attachments, moral sentiments, interpersonal stressors, and emotional communication. Brain regions involved in social feelings were confirmed by meta-analysis using the Neurosynth platform for large-scale, automated synthesis of functional magnetic resonance imaging data. Words that relate specifically to social feelings were identfied as potential research variables. Topical inquiries into social media behaviors, loneliness, trauma, and social sensitivity, especially with recent physical distancing for guarding public and personal health, underscored the increasing importance of social feelings for affective and second person neuroscience research with implications for brain development, physical and mental health, and lifelong adaptive functioning.

Brief Exposure to Infants Activates Social and Intergroup Vigilance

Among humans, simply looking at infants can activate affiliative and nurturant behaviors. However, it remains unknown whether mere exposure to infants also activates other aspects of the caregiving motivational system, such as generalized defensiveness in the absence of immediate threats. Here, we demonstrate that simply viewing faces of infants (especially from the ingroup) may heighten vigilance against social threats and support for institutions that purportedly maintain security. Across two studies, participants viewed and rated one among several image types (between-subjects design): Infants, adult males, adult females, and puppies in Study 1, and infants of varying racial/ethnic groups (including one's ingroup) and puppies in Study 2. Following exposure to one of these image types, participants completed measures of intergroup bias from a range of outgroups that differed in perceived threat, belief in a dangerous world, right-wing authoritarianism and social-political conservatism (relative to liberalism). In Study 1 (United States), stronger affiliative reactions to images of infants (but not adults or puppies) predicted stronger perceptions of a dangerous world, endorsement of right-wing authoritarianism, and support for social-political conservatism (relative to liberalism). Study 2 (Italy) revealed that exposure to images of ingroup infants (compared to outgroup infants) increased intergroup bias against outgroups that are characterized as threatening (immigrants and Arabs) and increased conservatism. These findings suggest a predisposed preparedness for social vigilance in the mere suggested presence of infants (e.g., viewing images) even in the absence of salient external threats.

Effects of Baby Schema and Mere Exposure on Explicit and Implicit Face Processing

In an increasingly multicultural society, the way people perceive individuals from the same vs different ethnic groups greatly affects their own and societal well-being. Two psychological effects that influence these perceptions are the Mere-Exposure Effect (MRE), wherein familiarity with certain objects or persons suffices for people to develop a preference for them, and the Baby Schema (BS), a set of specific facial features that evokes caregiving behaviors and an affective orientation in adults. In the present study, we aimed to investigate whether these two effects play a role in implicit physiological responses to babies vs. adults faces belonging to participants in-group vs. out-group. In study 1, the pupillary diameter of 62 Caucasian participants (M = 31; F = 31) who observed adult and infant faces of different ethnic groups (Caucasian, Chinese) was measured. In study 2, brain waves of 38 Caucasian participants (M = 19; F = 19), who observed the same set of faces, were recorded using EEG. In both studies, adults explicit preferences (i.e., attitudes) toward faces were assessed using questionnaires. In Study 1, females showed greater attention to infant than adult faces (BS effect) in both pupils, regardless of the ethnic group of the face. By contrast, males attended to infant more than adult faces for out-group faces only (BS effect). In Study 2, greater left posterior-parietal alpha activation toward out-group compared to in-group adult faces was found in males (MRE). Participants with a low BS effect toward in-group baby faces exhibited greater left posterior alpha activation to out-group than in-group baby faces (MRE). These findings reveal how different levels of sensitivity to in-group infants may moderate perceptions of both in-group and out-group baby faces. Questionnaire measures on attitudes showed that males and females preferred in-group to out-group adult faces (MRE). Participants in Study 2 also reported a greater preference for infants than adults faces (BS effect). These findings explicate the roles of gender and the Baby Schema effect in moderating implicit processing of in-group and out-group faces, despite their lack in moderating explicit reports. Contradictory findings at the implicit (physiological) and explicit (self-report) levels suggest that differential processing of faces may occur at a non-conscious level.

Nasal skin temperature reveals changes in arousal levels due to time on task: An experimental thermal infrared imaging study

Infrared thermography, thanks to technological developments and lowering prices, is now getting considerable attention as a potential arousal monitor in the safety industry. Nasal skin temperature might be a valid index to track physiological variations due to reduced arousal levels, and its use could prevent a drowsiness-related deterioration of performance. However, the few studies that have investigated nasal skin temperature in applied settings have had inconsistent results. Here, we assessed the validity of nasal skin temperature to monitor changes in arousal levels (from alertness to drowsiness). The participants performed a 2-h simulated driving task while we simultaneously recorded their nasal skin temperature, brain activity (we used frontal delta electroencephalographic [EEG] activity as the reference index of alertness), and driving performance (speeding time). For those variables, we calculated growth curve models. We also collected subjective ratings of alertness and fatigue before and after the driving session. We found that the nasal skin temperature showed a cubic trajectory (it increased for the first 75 min, and then it began to decrease, but such deceleration gradually diminished over time). As expected, frontal delta EEG activity showed an inverted U-shaped quadratic trend (EEG power increased for the first hour and half, and gradually decreased during the last thirty minutes). The speeding time exhibited a similar pattern of change. Subjective sleepiness and fatigue increased after the task. Overall, our results suggest that nasal skin temperature seems to be a valid measure of arousal variations while performing a complex and dynamic everyday task.

Infrared thermography of agonistic behaviour in pigs

Infrared thermography (IRT) or thermal imaging is increasingly being used as a non-invasive method to gain information on animals' physiological and emotional state. IRT has the potential to serve as a non-invasive quantitative assessment method but few studies have examined its utility in predicting welfare-relevant outcomes of dynamic scenarios relevant to commercial farming. This study used 1284 thermal images taken from 46 pigs in a controlled test environment while they engaged in an agonistic encounter (dyadic contest) at 13 wk. of age. Images were taken of the complete body from a dorsal perspective. A pilot study indicated that a rectangular thermal window on the back region was the most suitable and reliable area for obtaining temperature data in this situation. From this thermal window, the average, minimum and maximum temperature, standard deviation and coefficient of variation (CV) were obtained. These were analysed in relation to contest phase (from non-contact assessment, through escalated fighting to retreat), fight occurrence, contest duration, contest outcome (winner/loser status) and changes in blood glucose, blood lactate, and skin injuries. Variables showed a strong change in response to the moment of contest resolution (retreat of the loser); temperatures reduced sharply and CV increased, but did not differ between winners and losers. Contests that included a fight showed lower temperatures. Contest duration, body weight and sex only had minor influences on the temperatures. As the drop in temperature at contest resolution was irrespective of contest intensity, and the pattern was similar in winners and losers, this data potentially reflects vasoconstriction as a result of psychological stress rather than solely a physiological change. The study shows that peripheral temperature, as recorded by IRT, responds to the intensity and phases of a contest and may allow new insight into the physiological and welfare outcomes of aggressive behaviour.

Cognitive load and emotional processing in psoriasis: a thermal imaging study

Psoriasis is a chronic dermatologic disease which is frequently associated with psychological distress. Although studies suggest a relationship between this condition and difficulties in emotion regulation, behavioral and physiological evidence about this link is scarce. We measured implicit emotion regulation abilities of psoriasis patients and a healthy control group by examining the impact of distracting emotional (positive, negative or neutral) images on a working memory task ("Emotional N-Back") which could present high (2-back) or low (1-back) cognitive workload. Moreover, we used Functional Infrared Thermal Imaging to record participants' facial temperature and obtain a measure of the activation of the autonomic system. Rising of temperature over the peri-orbital areas and the nose tip are believed to reflect the activation and the de-activation of the sympathetic system, respectively. Patients scored higher than controls on the "Lack of emotional clarity" sub-scale of the Difficulties in Emotion Regulation Scale. Compared to controls, who performed much better in the low vs. high cognitive load condition, patients showed a smaller accuracy difference between the two conditions. Moreover, patients showed less sympathetic (lower peri-orbital and higher nasal tip temperature) activity (especially in the negative and neutral blocks) during the high vs. low cognitive load condition, suggesting that the former condition might be less emotionally demanding for them. Patients benefit more than controls from the load-dependent interference effect when dealing with emotional information; thus, therapeutic techniques aiming at teaching how to use cognitive strategies to downregulate emotions might be particularly appropriated for them.

Neurobiology of culturally common maternal responses to infant cry

This report coordinates assessments of five types of behavioral responses in new mothers to their own infants' cries with neurobiological responses in new mothers to their own infants' cries and in experienced mothers and inexperienced nonmothers to infant cries and other emotional and control sounds. We found that 684 new primipara mothers in 11 countries (Argentina, Belgium, Brazil, Cameroon, France, Kenya, Israel, Italy, Japan, South Korea, and the United States) preferentially responded to their infants' vocalizing distress by picking up and holding and by talking to their infants, as opposed to displaying affection, distracting, or nurturing. Complementary functional magnetic resonance imaging (fMRI) analyses of brain responses to their own infants' cries in 43 new primipara US mothers revealed enhanced activity in concordant brain territories linked to the intention to move and to speak, to process auditory stimulation, and to caregive [supplementary motor area (SMA), inferior frontal regions, superior temporal regions, midbrain, and striatum]. Further, fMRI brain responses to infant cries in 50 Chinese and Italian mothers replicated, extended, and, through parcellation, refined the results. Brains of inexperienced nonmothers activated differently. Culturally common responses to own infant cry coupled with corresponding fMRI findings to own infant and to generic infant cries identified specific, common, and automatic caregiving reactions in mothers to infant vocal expressions of distress and point to their putative neurobiological bases. Candidate behaviors embedded in the nervous systems of human caregivers lie at the intersection of evolutionary biology and developmental cultural psychology.

Dataset on genetic and physiological adults׳ responses to social distress

Both expectations towards interactions with conspecifics, and genetic predispositions, affect adults׳ social behaviors. However, the underlying mechanisms remain largely unknown. Here, we report data to investigate the interaction between genetic factors, (oxytocin receptor (OXTR) and serotonin transporter (5-HTTLPR) polymorphisms), and adult interactional patterns in shaping physiological responses to social distress. During the presentation of distress vocalizations (cries of human female, infants and bonobos) we assessed participants׳ (N = 42 males) heart rate (HR) and peripheral nose temperature, which index state of arousal and readiness to action. Self-reported questionnaires were used to evaluate participants' interactional patterns towards peers (Attachment Style Questionnaire, Feeney et al., 1994[1]), and the quality of bond with intimate partners (Experiences in Close Relationships Scale, Fraley et al., 2000 [2]). To assess participants׳ genetic predispositions, the OXTR gene (regions rs53576, and rs2254298) and the 5-HTTLPR gene (region SLC6A4) were genotyped. The data set is made publicly available to enable critical or extended analyzes.

The facial expression of schizophrenic patients applied with infrared thermal facial image sequence

BACKGROUND

Schizophrenia is a neurological disease characterized by alterations to patients' cognitive functions and emotional expressions. Relevant studies often use magnetic resonance imaging (MRI) of the brain to explore structural differences and responsiveness within brain regions. However, as this technique is expensive and commonly induces claustrophobia, it is frequently refused by patients. Thus, this study used non-contact infrared thermal facial images (ITFIs) to analyze facial temperature changes evoked by different emotions in moderately and markedly ill schizophrenia patients.

METHODS

Schizophrenia is an emotion-related disorder, and images eliciting different types of emotions were selected from the international affective picture system (IAPS) and presented to subjects during ITFI collection. ITFIs were aligned using affine registration, and the changes induced by small irregular head movements were corrected. The average temperatures from the forehead, nose, mouth, left cheek, and right cheek were calculated, and continuous temperature changes were used as features. After performing dimensionality reduction and noise removal using the component analysis method, multivariate analysis of variance and the Support Vector Machine (SVM) classification algorithm were used to identify moderately and markedly ill schizophrenia patients.

RESULTS

Analysis of five facial areas indicated significant temperature changes in the forehead and nose upon exposure to various emotional stimuli and in the right cheek upon evocation of high valence low arousal (HVLA) stimuli. The most significant P-value (lower than 0.001) was obtained in the forehead area upon evocation of disgust. Finally, when the features of forehead temperature changes in response to low valence high arousal (LVHA) were reduced to 9 using dimensionality reduction and noise removal, the identification rate was as high as 94.3%.

CONCLUSIONS

Our results show that features obtained in the forehead, nose, and right cheek significantly differed between moderately and markedly ill schizophrenia patients. We then chose the features that most effectively distinguish between moderately and markedly ill schizophrenia patients using the SVM. These results demonstrate that the ITFI analysis protocol proposed in this study can effectively provide reference information regarding the phase of the disease in patients with schizophrenia.

Acoustic Properties of Cries in 12-Month Old Infants at High-Risk of Autism Spectrum Disorder

There is preliminary evidence that infant siblings of children with Autism Spectrum Disorder (ASD) have an atypical pattern of cry, characterized by higher fundamental frequency and increased dysphonation. This prospective study collected multiple cry samples of 12-month old siblings of children with ASD (n = 22, 'high-risk' group) and 12-month olds with no family history of ASD (n = 27, 'low risk' group). While there was no difference between groups in the fundamental frequency or degree of phonation of the cry samples, the duration of each cry unit was significantly shorter in the high-risk siblings (p < .05). The six infant siblings who received a diagnosis of ASD at age two had amongst the shortest recorded cry durations.

Three physiological responses in fathers and non-fathers' to vocalizations of typically developing infants and infants with Autism Spectrum Disorder

Children with ASD, even before receiving a formal diagnosis, express atypical patterns of distress vocalizations (namely, episodes of crying). Their cries have higher fundamental frequencies, shorter inter-bout pauses, and fewer utterances. Cries of children with ASD are also perceived differently from other cries, and these perceptual differences may alter parent-infant interaction. This study assessed multiple physiological responses in fathers and non-fathers to atypical distress vocalizations (cries of children with ASD), acoustically matched typical distress vocalizations (cries of typically developing children), and positive vocalizations (laughter of typically developing children). The experimental procedures were designed to measure how components of the autonomic nervous system respond to typical and atypical infant vocalizations. Three convergent methodologies (Galvanic Skin Response-GSR; cardiac dynamics via Inter-Beat Interval-IBI; right hand temperature change-RHTC) were performed on two groups with contrasting caregiving experience: fathers of typically developing children (n=10) and non-fathers (n=10). Inferential statistical analysis compared the two groups (fathers, non-fathers) and three stimulus types (ASD cry, typical cry, laughter) for the three measures (GSR, IBI, RHTC). Both fathers and non-fathers showed greater negative responses (increased GSR) to ASD cries compared to typical cries and laughter. Fathers showed higher IBI and greater temperature increases (RHTC) than non-fathers while listening to typical and atypical cries. Fathers and non-fathers showed more emotional arousal mediated by sympathetic activation while listening to cries of children with ASD. Fathers were calmer and acted more promptly than non-fathers while listening to typical cries, perhaps because the fathers had more experience in caring for crying infants. These findings point to similarities and differences in fathers' and non-fathers' physiological responsiveness to cries of children with ASD and might guide specific intervention programs for parents of children at risk of ASD.

Maternal bonding in childhood moderates autonomic responses to distress stimuli in adult males

Mother-child bonding influences the development of cognitive and social skills. In this study we investigate how maternal attachment, developed in early childhood, modulates physiological responses to social stimuli later in life. Our results suggest that the autonomic nervous system's responses to vocal distress are moderated by the quality of participants' maternal bonding. In particular, participants with optimal maternal bonding showed a greater calming response to distressful stimuli whereas participants with non-optimal maternal bonding showed a heightened distress response.

Baby, you light-up my face: culture-general physiological responses to infants and culture-specific cognitive judgements of adults

Infants universally elicit in adults a set of solicitous behaviors that are evolutionarily important for the survival of the species. However, exposure, experience, and prejudice appear to govern adults' social choice and ingroup attitudes towards other adults. In the current study, physiological arousal and behavioral judgments were assessed while adults processed unfamiliar infant and adult faces of ingroup vs. outgroup members in two contrasting cultures, Japan and Italy. Physiological arousal was investigated using the novel technique of infrared thermography and behavioral judgments using ratings. We uncovered a dissociation between physiological and behavioral responses. At the physiological level, both Japanese and Italian adults showed significant activation (increase of facial temperature) for both ingroup and outgroup infant faces. At the behavioral level, both Japanese and Italian adults showed significant preferences for ingroup adults. Arousal responses to infants appear to be mediated by the autonomic nervous system and are not dependent on direct caregiving exposure, but behavioral responses appear to be mediated by higher-order cognitive processing based on social acceptance and cultural exposure.

Immediate and selective maternal brain responses to own infant faces

Infant faces elicit caregiving in adults. In previous research on brain responses to images of infant faces, the faces were unknown to participants. This study investigated EEG in primiparous mothers of 3- to 6-month-old infants viewing their own infant's face compared to an unfamiliar but appearance-matched infant's face. Spectral power was calculated and compared, and power at three EEG bands (delta, theta, and gamma) was found to differ between faces. Brain responses among primiparous mothers distinguish images of their own versus unfamiliar infants.