The present study produced three major results, that we summarize in the following points. First, there was a clear differentiation in children’ conceptualization (in terms of arousal and valence) as a function of different emotions; besides, the psychophysiological measures were highly modulated by emotional types, and arousal and valence parameters accounted for the psychophysiological variations in relationship with different emotional patterns; finally the presence of two different types of task – a facial expression decoding and a script comprehension –induced significant differences in the subjective representations only for a limited number (mainly disgust) of emotions.
For the first time we used multimodal measures to explore the evaluation effect (based on valence and arousal) on psychophysiological behavior taking into account an ample range of emotions. Secondly we applied this multimodal approach to study the specific domain of facial expression of emotions whereas other previous research did not specifically consider this emotional domain. Thirdly we considered the facial expression of emotion with and without an emotional script context to study the contextual impact on face decoding. Therefore the situated perspective was adopted in the present research.
As hypothesized by the dimensional approach to emotion[52, 53], the representation of the emotional domain was based on a conceptual space defined by two exes, arousal and hedonic value. In particular, the emotions with a high arousal level and a negative value were better understood, if compared with other emotions. Specifically, the emotions of fear, anger and surprise were well recognized and well labeled. A significant higher arousing power was attributed to them, and these emotions were also considered as more negative. Moreover, they were better recognized than the other emotions, specifically in comparison with sadness and disgust. The positive emotion of happiness was considered as less arousing and more positively valenced and it was well represented and recognized. On the contrary, disgust appears to be more difficult to be identified, as well as sadness, and they both were considered as less arousing and less negative. It should be considered that in present research we opted to evaluate the ability of subjects in spontaneously labelling the face/script they saw. As revealed, disgust and sadness were not immediately labelled, but in many cases they were correctly described (using a semi-structured interview) only after a successive enquire. Therefore, the subjects showed a general ability in recognizing the two emotions, although this recognition was less immediate. It should be based on the increased complexity to decode these emotions, because they are learned only successively in comparison with other primary emotions (such as anger and fear).
Therefore a first main result of the present study was that the dichotomy pleasure/displeasure and high/low arousal was considered relevant by the subjects, confirming a significant role in emotion representation, as indicated by previous researches[19, 53, 54]. In fact, not only the hedonic category was systematically well represented, but it was correctly identified in terms of negativity or positivity. Moreover, arousal rating can be considered a predictive cue of the ability to classify and differentiate emotional correlates. Indeed, it was correctly used when the child was able to attribute an adequate label to the emotion, while when the child cannot conceptualize the emotion, the arousal value seems to be more ambiguous (for example for disgust) or less relevant (sadness).
As regard to more negative and arousing emotions (fear, anger and surprise) some recent study[55, 56] revealed high rates of recognition, that the researcher attributes to the central adaptive function of these negative high arousing emotions. Indeed, they has a main role for the individual safeguard, both on an ontogenetic and a phylogenetic level. They may be represented as a cue in order to detect unfavorable environmental conditions[19, 54]. Accordingly to the functional model[57, 58], the emotional expressions represent a response to a particular event, significant in terms of costs and benefits for people. Specifically, the expression of anger and fear represents the perception of a threat for the personal safeguard and, therefore, it requires a greater investment of attentional resources. The prominence of specific category of emotion (more negative and arousing) may suggest their central role in emotion acquisition in comparison with other less relevant (and less arousing) emotions in childhood.
The script condition introduces another main explicative factor, regarding the emotional representation. Indeed, the presence of a specific context generally does not affect the correctness of the emotional label attribution, but it produces a discriminant effect exclusively for one emotion, that is disgust. Indeed in presence of a specific situational context disgust was better characterized in terms of arousal (more clearly arousing) and valence (more negatively valenced). The presence of the interactional features that characterize the emotional experience seems to introduce a facilitation element for emotion comprehension, also producing a better description in the emotion labeling (more correct recognition). It was possible to state that the situational component constitutes a facilitation cue, because it allowed the subjects to activate a more complex conceptual representation, which takes into account the context in which the emotional event happens, the emotional causes, the logical order of actions and their consequences.
It was noticeable, however, that the script enables a wider and a more complete representation only in case of a this “secondary” emotion, which maximally has a benefit from the situated condition. It was observed that emotion recognition was allowed by the development and the generalization of an emotional script, that is, a child can recognize a specific emotion by verifying the presence of several prototypical elements that are arranged in precise causal and temporal sequences. These scripts include not only facial expressions, but also the representation of causal factors, physical and social context, several actions and their consequences, as well as the cognitive appraisal of the situation and the subjective experience. Among these cues, the representation of the causal bonds, that is a set of causal events and of their behavioral consequences, has a remarkable significance, because they constitute the more explicative elements of the emotional experience[5, 45, 59].
To conclude, even if our study does not allow us to state which of the two representational modalities (facial pattern comprehension or script decoding) precedes the other, it was possible to observe that the situational correlates provide a facilitation cue for the representation of emotional correlate when a secondary emotion is represented. However, no specific facilitation effect was observable in case of “primary” emotions, which were well recognized and described also in absence of contextual cues.
A relevant main result of the present research was related to the psychophysiological measures which were shown to vary in concomitance to the type of stimuli (different emotions) and to the categorization process (the subjective ratings). In fact, subject revealed a coherent psychophysiological behavior in response to the emotions, independently from the condition (script or face). Moreover, it was shown that SCR, HR and EMG were modulated as a function of the two main axes of valence and arousal, as they were rated by the subjects.
Firstly, SCR was shown to be increased when children processed emotional faces and scripts rated as high arousing and negative (anger, fear and surprise), whereas it decreased in concomitance with stimuli rated as low arousing (mainly sadness, disgust, and neutral patterns). A similar profile was observed for HR, which showed higher values in case of more positive, more negative and arousing stimuli. These results were in line with many other studies on adults, which postulated a significant HR effect for more arousing and relevant stimuli[33–36]. Moreover, the variation in term of arousing power (high vs. low) may determine the different impact of the emotional cues, since perception of a high arousal generally induces a consistent HR increasing independently from the stimulus valence. These multiple parameters and their combination were relevant to comprehend the effect of emotions on psychophysiological data.
An important result was also observed for the facial EMG values. Indeed we found that children were highly responsive to facial stimuli and scripts, by adopting a sort of “facial feedback” modality, since they used similar facial configurations displayed by the pictures (consonant behavior). It was observed an increasing of mimic activity in case of some conditions: the different emotions evoked distinct facial EMG response patterns, with increased zygomatic muscle activity to positive patterns and increased corrugator muscle activity to negative patterns, whereas both the corrugator and the zygomatic muscle response patterns were less pronounced in sadness, disgust and neutral condition. More generally, corrugator muscle activity was increased in response to more negative and arousing stimuli, mainly for fear, anger, and surprise. In addition, as revealed by regression analysis, arousal parameter showed to explain in greater measure the corrugator modulation, whereas valence was less relevant to describe the psychophysiological activity in response to negative, highly arousing patterns. Contrarily, zygomatic muscle was modulated by both arousal and valence, with significant increasing responsiveness related to happiness.
These variations may mark a psychophysiological response in case of a high arousing situations, since relevant (with arousing power) stimuli seem to produce and reinforce a coherent psychophysiological behavior. Contrarily, subject reported a reduced arousing power for sadness and partially for disgust, fact that may explain the concomitant reduced EMG, SCR and HR values. Thus, more arousing conditions showed a perfect consonance between subjective evaluation and psychophysiological (both facial and autonomic) measures. Specifically, anger, fear, surprise and happiness were rated as more emotionally involving. In parallel, the psychophysiological behavior was responsive of this subjective self-evaluation, with an increased “positive” (zygomatic) facial expression and a higher autonomic activity (increased HR) for happiness, from one hand; an increased “negative” (corrugator) facial expression and higher arousal response (more SCR and HR) for anger, fear and surprise, from the other.
However, more generally the modulation of psychophysiological measures was mainly related to arousing power more than to valence, since independently from the valence, the stimuli rated as high arousing (anger, fear, surprise and happiness) were able to induce a more significant and coherent emotional response. Regression analysis confirmed these results: mainly arousal attribution was significant to determine the psychophysiological variations, able to explain SCR, HR and facial response modulation, since subjects “shared” the facial behavior and autonomic activity observed in both positive vs. negative conditions.
Thus, in general psychophysiological measures may be interpreted as functional mechanism of “mirroring” the emotional condition displayed by the facial stimuli, where “sharing” similar emotional responses allows a direct form of understanding and recognize emotion by a sort of simulation process. More specifically, contexts evaluated as emotionally involving and significant may ingenerate a consonant shared response by the observer, who firstly recognizes and secondly “mimic” (by face and autonomic behavior) the somatic markers related to the experienced emotions. Moreover, based on these results we may suggest that the gradual development of emotional competencies proceeds from more basic and simple emotions, which are primarily acquired by children, to more complex and less prominent emotions, which might be less relevant in terms of salience. Brain correlates may support this different learning process, related to a “maturation effect” which might explain more deeply the early acquisition of the recognition abilities in response to more salient and relevant emotions in term of human safeguard and the successive acquisition for the less relevant (less threatening and primary for the safeguard) emotions.
To summarize, self-report measures were replicated by psychophysiological behavior, that showed to vary coherently in relationship with different emotions. Children revealed a consonant and adequate behavior in terms of labeling (correct recognition), evaluation (valence and arousal attribution) and psychophysiological responsiveness. However, a clear advantage was observed for some specific emotions, those rated as more arousing and negative (fear, anger and surprise). It was suggested these emotions may be central to people safeguard and they may be priority developed by children. Arousal attribution was considered as the most critical parameter to explain the emotion recognition process and the psychophysiological behavior. Contrarily, sadness and disgust were less prominent in terms of both arousal and valence, and in some cases they were also less correctly recognized. The contextual cues (script condition) may allow to perform a better attribution, mainly for the emotion of disgust. In case of more complex emotional cue, the context (script) contribution was relevant to complete the correct recognition.
However, about the main limitations of the present study, future research may explore more directly the intrinsic effect induced by facial expression of emotion taking into account also gender effect. Indeed previous research found significant differences between male/female children in response to the emotional type. Secondly, the arousal effect we found in the present study should be better considered in relationship with different emotional valence taking into account a wider range of facial expressions which may cover the ample orthogonal axes low/high arousal positive/negative valence. Thirdly, due to the limited sample we used for the present research, it is crucial to integrate the present data with an ampler sample size, in order to extend the present results to a general population.