arousal and valence

14 Pages·2014·1.07 MB·English

Balconietal.BehavioralandBrainFunctions2014,10:32
http://www.behavioralandbrainfunctions.com/content/10/1/32
RESEARCH Open Access
Multilevel analysis of facial expressions of
emotion and script: self-report (arousal and
valence) and psychophysiological correlates
Michela Balconi*, Maria Elide Vanutelli and Roberta Finocchiaro
Abstract
Background: The paper explored emotion comprehension inchildren with regard to facial expression of emotion.
The effect ofvalenceand arousal evaluation, of context and of psychophysiological measures was monitored.
Indeed subjective evaluation of valence (positive vs. negative) and arousal (high vs.low), and contextual (facial
expression vs. facial expression and script) variables were supposedto modulate thepsychophysiological responses.
Methods: Self-report measures (in terms of correct recognition, arousal and valence attribution)and
psychophysiologicalcorrelates(facial electromyography,EMG,skin conductance response, SCR, and heart rate, HR)
were observed when children(N=26; mean age=8.75 y;range 6-11 y) looked at sixfacial expressions of emotions
(happiness, anger, fear, sadness, surprise, and disgust) and sixemotional scripts (contextualized facial expressions).
The competenciesabout the recognition, the evaluation onvalenceand arousal was testedin concomitance with
psychophysiologicalvariations.Specifically, wetested for the congruence of thesemultiple measures.
Results: Log-linear analysis and repeated measure ANOVAs showed different representationsacross the subjects, as
a function of emotion. Specifically, children’ recognition and attributionwere well developed for some emotions
(such as anger, fear, surprise and happiness), whereas some other emotions(mainly disgust and sadness) were less
clearly represented. SCR, HR and EMG measures were modulatedby the evaluation based onvalence and arousal,
withincreased psychophysiological values mainly in response to anger, fear and happiness.
Conclusions: As shown by multiple regression analysis, a significant consonance was found between self-report
measures and psychophysiological behavior, mainly for emotionsrated as more arousing and negativein valence.
The multilevel measures were discussedatlight ofdimensional attributionmodel.
Keywords: Facial expression of emotion,EMG, Valence, Psychophysiology
Introduction skills are important predictors of children’s emotional
In the last two decades, developmental psychology has awareness[3].
seen an increasing interest in the study of emotion com- More specifically, Bullock and Russell [4] proposed a
prehension. Specifically, emotional face recognition and model in which children acquire a system to represent
understanding represent a primary social competence, and classify emotions which is based on a limited num-
because they contribute to social interactions and social ber of wide categories. The most important of them are
management [1]. These competencies are related to gen- the two dimensional axes of the hedonic value and the
eral cognitive functions and it was shown that language arousal level. This model was tested by some empirical
was the most important predictor of nonverbal emotion studies which found that firstly children interpret facial
recognition ability [2]. Indeed both gender and verbal expressions in terms of pleasure-displeasure (bipolar he-
donicvalue)andintensity(arousallevel).Onlysuccessively
they use more articulated and wider conceptual categories
*Correspondence:[email protected]
[5,6]. To verify the type of categorization applied to the
ResearchUnitinAffectiveandSocialNeuroscience,Departmentof
Psychology,CatholicUniversityoftheSacredHeart,MilanLargoGemelli,1, emotional domain, affective responses organized around
20123Milan,Italy
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reproductioninanymedium,providedtheoriginalworkisproperlycredited.TheCreativeCommonsPublicDomain
Dedicationwaiver(http://creativecommons.org/publicdomain/zero/1.0/)appliestothedatamadeavailableinthisarticle,
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the arousal and valence dimension include subjective specific difficulty in understanding the emotions that
experience, often measured using self-report responses to presentalackofcorrespondencebetweenpeopleexpecta-
affective stimuli. At this regard, Self-Assessment Manikin tions and environment events. These emotions have an
(SAM)wasusedtotestthissubjectiveemotionalcorrelates external and social origin, such as surprise, dismay, and
[7].Itwasalsodemonstratedthatage,facialexpressionin- astonishment. In parallel, Capps, Yirmiya, and Sigman
tensity and emotion category are important for predicting [20]observedagreaterimpairmentinrecognizingandla-
accuracyonemotion-processingtasks[8]. belling the expression of those emotions that have an ex-
Previous results demonstrate how task type and chil- ternal locus of control and, simultaneously, that require a
dren’s mood influence children’s emotion processing [9]. wide knowledge of the social scripts and of their social
Indeed, in order to explain this developmental process, consequences. In line with this hypothesis, Baron-Cohen,
the type of emotions children have to recognize is a first Spitz,andCross[22]suggestedthatthe comprehensionis
mainfactorrelatedtodecodingcompetencies [10].More more difficult for emotions that imply the activation of
generally, in line with Russell’s model of emotional ex- some cognitive functions, such as mentalization and
perience, emotion fundamentally varies activation in metarepresentation. In general, previous results provide
centrally organized appetitive and aversive motivational evidence for late developmental changes in emotional ex-
systems that have evolved to mediate the wide range of pression recognition with some specificity in the time
adaptive behaviors necessary for an organism struggling coursefordistinctemotions[23].Indeeditwasfoundthat
to survive in the physical world [11-13]. Most pleasant some emotions, like disgust and sadness, are more often
affects are held to be associated with the appetitive mo- confused with other primary and early developed emo-
tivation system; unpleasant affects with defensive motiv- tions, such as anger or fear and they are not spontan-
ation [14]. Thus, a primary distinction among emotional eouslylabelledincomparisonwithotheremotionssuchas
events is whether they are appetitive or aversive, positive anger,fearorhappiness.
or negative, pleasant or unpleasant, which clearly relates Thus, it was also supposed that, through a progressive
to the motivational parameter of direction. Secondly, all processofscriptgeneralization,a“situated”comprehension
agree that hedonically valenced events differ in the de- of emotions arises. The process of emotion categorization
gree of to which they arouse or engage action, which is iswellillustratedbytheuseofadequateattribution.Indeed,
related to intensity parameter. Emotional intensity prob- emotionallabelsconstitutethefinalstepofadevelopmental
ablyreflectsthestrengthofactivationinmotivationalsys- process that goes through a “dimensional attribution”
temssubservingappetitiveanddefensivebehaviorsand,as (characterized by the presence of pleasure-displeasure cor-
such,hasimpactonthetypeofphysiologicalresponse.In- relate) to a “situational attribution” (the script representa-
tensity was conceptualized as “predator imminence”, or tion). This should be taken into consideration in studying
the distance of the threatening pattern from the subject the development of emotional decoding, because these
[15] orintermsofdistancefromanaversiveorappetitive competencies seem to be bound not only to cognitive but,
goal [16]. More generally, arousal in humans appears to above all, to social and communicative competencies,
reflect the degree to which a stimulus elicits appropriate which have an influence on emotion conceptualization.
appetitive or defensive behaviors. Thus, the two dimen- Thus, another main concern is represented by contextual
sions of pleasure and arousal explain the majority of the andsituationalelementsthatcauseemotionandthatmight
emotionalexperienceandsubjectivejudgment,andthein- facilitateornottheemotionprocessingandcomprehension
creasedperceptionofemotionalsignificanceofastimulus [24].AsRussellandWiden[25]underlined,ineverydayex-
in term of valence may increase the perception of its perience children use facial expressions in order to infer
arousingpower[17]. emotions.Ontheotherhand,thefacialcuesarealwayslo-
Secondly,itshouldbenotedthatyoungsubjectsshowed cated in an interactive context. In other words, it is neces-
tobecompetentinthedecodingoftheprimaryorsimple sary to take into account the role of a wider socializing
emotions (e.g. happiness and anger), but they have more context. Therefore, the concept of emotional context,
difficulties in processing secondary or complex emotions, considered asa complex and multidimensional representa-
such as pride and embarrassment [18-20]. To identify tion of situational events, is relevant in facial expression
these emotions more time and more informational cues processing.
must be analyzed. Moreover, as regard to the secondary Thirdly, it was observed that behavioral and physio-
emotionsoremotionsdevelopedonlylaterduringthede- logical responses to emotional pictures co-vary with
velopmental phases, a more accentuated difficulty in un- system evaluation (pleasure/displeasure) and motive in-
derstandingcausalantecedents(theeventsthatcausedthe tensity (arousal) [26,27]. Psychophysiological responses
emotion expressed by face) and contextual relations (the are not directly observable, and they include cardiovas-
social situations in which the emotion is produced) cular, electrodermal, respiratory measures, etc. It was
emerges [21]. Bormann-Kischkel et al. [10] observed a underlined that emotion comprehension plays a critical
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role in adaptive behavior, since it promotes survival and emotional arousal were co-varied, skin conductance re-
guides human behavior by exerting a direct influence on sponseswerelargestforhighlyarousingstimuli,irrespect-
brain responsiveness and psychophysiological activities. ive of hedonic valence [40], consistent with the notion
Between the others, facial action revealed by EMG meas- that these reactions primarily reflect differences in emo-
ure (electromyogram), heart rate, and skin conductance tionalarousal,ratherthanhedonicvalenceperse.
wereobserved to variate in concomitanceofpleasure and About these psychophysiologicalvariationsin response
displeasurereportswhileviewingofemotionalpatterns. to emotions and facial stimuli, an important debate
More specifically, about the psychophysiological mea- regards the presence of a coherent response by psycho-
sures, facial behavior using electromyography (EMG) physiological measures in childhood, as it was observed
suggested they were sensitive to the valence dimensions, in adult behavior. Previous research found consistent
with increased corrugator activity in response to unpleas- patterns of psychophysiological activation also by chil-
antpatternsandzygomaticactivityinresponsetopleasant dreninresponsetoemotionalstimuli[41,42].Nevertheless,
patterns. Facial EMG (electromyographic) activity accom- to verify the coherence of these physiological measures in
panieschangesinappetitive(positive)anddefensive(nega- youngpeopleinresponsetofacialemotionalpatterns,spe-
tive) activation [28]. Specifically, the corrugator muscle cific analysis should be conducted which included both
appears to be responsive of to judgment of unpleasant arousalandvalenceparameters.
event compared to neutral pictures [27]. Many studies Therefore,emotionalbehaviormanifestswithinmultiple
found a consistent and significant relationship between domains,comprehendingconceptualandself-reportattri-
corrugator and hedonic valence, with greater corrugator bution, autonomic responses (physiological systems), and
activity elicited when viewing the most unpleasant stimuli the comprehension of contextual components, which all
[29]. Moreover, Bradley, Codisposti, Sabatinelli, and Lang may have a significant role in this process. However, no
[30] showed that pictures that produce disgust (for ex- previous study has directly analyzed the relationship
amplemutilation),thatwerehigherinarousal,promptlar- between these multilevel measures, that is self-report
gerchangesthanotherunpleasantpictures. evaluation based on valence and arousal parameters, psy-
Other physiological measures of emotional behavior in- chophysiological behavior and contextual cue variability.
cludeheartrate(HR),withobservedincreasedHRacceler- The present study was finalized to explore the conver-
ationtopleasantpatternsandincreasedHRdecelerationto genceofthesedifferentmeasures.
unpleasantpatterns[30].Moreover,investigationsexploring In the present research the effect of some main factors,
cardiovascularactivityinemotionperceptionassessedvari- valence modulation (emotional type) from one hand, and
ations as a function of differences in stimulus intensity, as contextual effect (face alone vs. facial display within a
this variable was revealed critical in eliciting orienting or script), from the other, was considered. Specifically, we
defense response [27,30-32]. Low-intensity stimuli were explored their influence on physiological reactivity (auto-
foundtorelatewithheartratedeceleration,whereasintense nomic activity) and emotional attribution (self-report
stimuli were observed to activate defense responses associ- attributional process), which are all relevant to the de-
atedwithheartrateacceleration[33-36].Nevertheless,also scription of the emotional responses [26,43]. Thus, the
contrasting results were collected, since heart initially de- purpose of this study is to verify the attended psycho-
celerated, rather than accelerated, when people viewed physiological and attributional responses to emotion vari-
picturesofunpleasantemotionalevents,contrarytotheno- ation,and,secondly,toshowthattheattributionalprocess
tions that these aversive stimuli might prompt defensive wasrelatedtovalenceandtocontextmodulation.
heartrateacceleration[27,30,37].However,differentexperi- Previous assumptions should be strengthened by the
mental paradigms were adopted in previous research and, followinghypotheses:
insome cases,no directcomparisoncanbe conducted be-
tweenthem. 1) Facesevaluatedasmore negative orpositiveinterm
Moreover, it was found electrodermal activity (Skin of valenceand arousing power shouldelicitmore
Conductance Response, SCR) consistently varies with intenseresponses,beingthe subjectsmore engaged
emotionalintensity,withlargerresponseselicitedineither with thestimulus,whereasneutral stimulishouldbe
unpleasant and pleasant context and that are more lessinvolvingandintense,and, consequently,differ
pronounced in those that are rated as highly arousing inaffective ratingfrom emotional stimuli. The
[27,38,39]. Thus, also electrodermal reactions increase interactioneffectofthesetwoparameters(i.e.
withincreasesindefensiveorappetitiveactivation[30,37]. valence and arousal) isalsoexpected.Thiswould
Ingeneral,itwasfoundincreasedskinconductancewhen suggest thateffectsduetoemotionalarousalshould
peopleviewpicturesratedasemotional,comparedtoneu- begreaterforhighly unpleasant andpleasant
tral,regardlesstheyareratedpleasantorunpleasantinhe- stimuli,whichwereratedasslightlymore arousing
donic valence [27]. However, when hedonic valence and thanstimulievaluatedaslesspositive/negative [44].
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2) Secondly,HR,EMG, andSCR shouldshow a functionasafacilitationcuetocorrectlyinterpretthe
modulationincorrelationwith emotionallyrelevant, wholeemotionalevent.Thisfacilitationshouldbe
arousing and pleasantorunpleasant stimuli. We mainlymoreevidentforthesecondaryemotions,as
expectedthat subjectsmightbemore emotionally disgust,becauseinordertocomprehendthisemotion,
involvedbyahighly negative orpositiveand more subjectshavetounderstandsomecontextualor
arousing stimulusthanneutralor low-arousingpic- “external”elements.Finally,thisfacilitationeffect
tures,and thatthey mighthaveamoreintensepsy- shouldbesupportedbypsychophysiologicalmeasures,
chophysiologicalactivationwhile viewinganegative andinparallelsituationalcuesshouldsupporttheSCR
orpositivethananeutralpatternwhentheyare also increasing(morepositiveandnegativeemotions);the
perceivedasmore arousing [13].This shouldpro- increasedcorrugatoractivityinresponsetonegative
duce anincreasedSCRandHR response,and the emotions,andtheincreasedzygomaticactivityin
modulationoffacialEMG.Specifically, weexpected responsetopositiveemotions.
an increasedSCR formore positive andnegative
emotions,an increasedcorrugatoractivityinre- Method
sponse tonegativeemotions andan increasedzygo- Participants
maticactivity inresponsetopositiveemotions. The sample includes 26 normal children. Ages varied
Finallyageneral higherHR shouldbeexpected from6to11(M=8.75;S.D.=0.78;range=6-11.5;15fe-
mainlyformore arousing emotions. males and 11 males). None of them presented cognitive
3) Furthermore,weexpectthatchildrenmay have or linguistic deficits. With regard to cognitive compe-
more difficultiesto decode and understandemotions tencies, children presented a middle-high or high func-
generallyconsideredasmore complex and learned tioning cognitive profile (WAIS-IV FSIQ: M=87; range:
onlysuccessively(such asdisgust)rather than 70-120). No history of psychiatric or neurological impair-
primarybasicemotions (such ashappiness,anger, mentswasobservedfortheparticipants.Indeedtwoneuro-
and fear). Inparticular,wefocus ourattentionon psychologists applied a specific semi-structured interview
therepresentationofthe dimensionalaxesof before the experimental session to test no clinical impair-
hedonic/arousal value, thatengendersthe ments. The presence of other deficits on the perceptive or
acquisitionofamore complexconceptual cognitivelevelswasexcluded.Child’parentsgaveinformed
representation [5,45].Thanks tothisacquisitionit written consent to participate in the study by their sons,
canbeproducedthe developmentalprocess,that andtheresearchwasapprovedbythelocalethicscommit-
includesaninitialcompetenceinthediscrimination tee (Catholic University Ethic Committee, Department of
of basicemotionalcategoriesand a successive Psychology).
comprehension ofmore complexemotional
categories(asdisgustorsadness).Thuswesupposed Materials
thataboutthese emotions children couldhavemore Facialstimuli
difficultytogivea spontaneous attributionalcorrect Thefacialstimuli(cardboardsblackandwhite10cm×10
attribution(intermof valence andarousal)tothe cm), which consist of an emotional face of a young boy
facialpatterns.Secondlythey shouldbeless showingsixemotions(happiness,sadness,anger,fear,dis-
physiologically responsivetotheseemotionalcues, gustandsurprise)andoneneutralface.Thestimulusma-
basedontheintrinsic relationshipthatwe expected terial was selected by Ekman and Friesen database [46].
toexistbetweenattributionaland Wehaveoptedforayoungactoragedsimilarlytotheex-
psychophysiologicalprocesses. perimentalsubjects,inordertofacilitatetheidentification
4) Fourthly,basedonthe“situational”perspectiveto process, which would make easier the recognition task
explainfacialemotioncomprehension,wemay (Figure1a).
supposethatemotiondecodingistheresultofthe
elaborationofmultipleemotionalcues,amongwhich Emotionalscripts
facialpatterns(facialexpressions),behavioralcorrelates The material consists of 6 pictures (coloured cardboards
(thecausalbondsbetweenevents),aswellasspecific 10 cm×15 cm) with an emotional content and one neu-
contextualfactors(elicitingemotionalcontext).The tral picture (see Figure 1b). Pictures illustrate contextu-
comparisonbetweentwodifferenttypesofcondition alized situations eliciting the emotional correlates of
(onlyafacialexpressionofanemotion;afacial happiness, sadness, anger, fear, surprise and disgust
expressionwithinanemotionalscript)allowsusto [5,45]. In particular each picture presents a character (a
exploreindetailtheroleoftheelicitingcontextinthe girl or a boy) in an interactive context (with peers or
emotion.Wesupposethatscriptfacilitatessubjects’ adults). In addition, the presence of a clear emotional fa-
recognition.Accordingtoourhypothesis,ascriptwill cialexpressionwasconsideredadiscriminantstimulusfor
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Figure1Examplesof(a)facialstimuliand(b)emotionalscripts.
the selection of the pictures. The pertinence of the emo- represented subjects), and the complexity (number of de-
tional content for each emotional script, the homogeneity tails represented) were tested witha 5-points Likert scale.
of the stimuli in terms of cognitive complexity and famil- No significant differences were found between emotions
iarity were tested in a pre-experimental phase (12 males forhomogeneityF(6,11)=1.18,p=.40;andcomplexity:F
and females; 6-11 years). Stimulus homogeneity, intended (6,11)=1.64,p=.31).
as the degree of difficulty in comprehending the situation Ineachphase,firsttimestimuliwerepresentedsimultan-
represented in the script (clarity of the context and the eously, in order to allow familiarization with the material.
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Inasecondassessment,theywerepresentedoneattime,in from analysis, whereas trials with no detectable response
a random sequence, varying the order of the stimulus werescoredaszero.Facialelectromyographic(EMG)ac-
across the participants. Furthermore, to avoid a possible tivity in the zygomaticus major and corrugator supercilii
order effect between the experimental conditions, some muscle regions were considered. The electrodes (4 mm
subjects were submitted to face decoding condition and diameter Ag/AgCl electrodes), filled with Surgicon elec-
successively to emotional script condition, whereas other trolyte paste, were positioned over the corrugator and
subjects decoded the stimulus materials in an opposite se- zygomatic muscles in accordance with guidelines for psy-
quence (firstly the emotional script and then the facial chophysiologicalrecording[49,50].Frequenciesofinterest
expression). generallyrangedfrom20to400Hz.Corrugatorandzygo-
maticEMGresponsesweresuccessivelyscoredasthedif-
Procedure ference between the mean rectified corrugator/zygomatic
Subjects were told that they had to evaluate some pic- signals present during the presentation of the stimuli and
tures (faces or scenes) based on some rating scales. Self- themeanrectifiedsignalsinthe1spriortostimuluspres-
Assessment Manikin was used to test the self-report entation(baselinemeasure).Apositivevalueindicatesthat
measures on a nine-point scale hedonic value (positive/ the corrugator/zygomatic measures were greater during
negative) and arousal value of the emotional content the experimental phase than during the baseline phase.
(more/less arousing) [7]. After each presentation of the All the data were acquired for the time interval of stimu-
stimulus (stimulus presentation duration=15 sec.) sub- luspresentation(15sec.)andsuccessivelynormalized.
jects were invited to evaluate it, no longer viewing the The exact synchrony between the stimulus presentation
image. During stimulus presentation subjects’ psycho- and the psychophysiological data acquisition was guaran-
physiological responses were acquired. Furthermore, teedbytheintroductionofspecificmarkerbyasecondex-
through a half-structured interview grid [47], the experi- perimenter, simultaneously to the onset of the stimulus
menter invited the child to observe the stimulus set and presentation.Asuccessiveanalysisofthevideo-tapedregis-
to describe the emotional feelings represented (“What is tration of the entire experimental session furnished other
that facial expression?”).Itwasmade anotherfocalques- checkingofthissynchrony.
tion about the situation illustrated by the pictures
(“What happened?”). Interviews were audio- and video- Analysis and results
taped and scored verbatim. Three judges examined the Self-reportmeasures
verbalmaterialencoded,inordertoanalyzespecificcon- The statistical analysis applied to self-report measures in-
ceptualcategoriesrelativelytothecorrectnessoftheverbal cludedtwosteps:afirststep,wherelog-linearanalysiswas
labels(correctrecognition).Forthefirstlevelofanalysis,a applied to correctness of emotional evaluation; a second
correct answer included an explicit emotional label (such step,whererepeatedmeasureANOVAswasapplied.Type
as“happiness”)orsynonymousterms(“joy”)[47]. I errors associated with inhomogeneity of variance were
controlledbydecreasingthedegreesoffreedomusingthe
Psychophysiologicalrecordingprocedure Greenhouse-Geiserepsilon.
SCR,HRandEMGdatareduction A log-linear hierarchical analysis (saturated model) was
Skin conductance response was measured continuously applied to subject labeling (correct labelling of emotion)
with a constant voltage by Biofeedback (Biofeedback with factors correctness (correct/incorrect, 2) × condition
2000, version 7.01). Before the attaching electrodes, the (face/script, 2) × emotion (type, 7) variables (see Areni,
skin was cleaned with alcohol and slightly abraded. SCR Ercolani, Scalisi) [51] (Table 1). In both conditions (emo-
was recorded from two electrodes placed on the medial tional face and script), the emotions were largely recog-
phalanges of the second and third finger of the non- nized by the subjects. In fact, they correctly labeled each
dominant hand. The sample rate was of 400 Hz. SCRs emotion(withincreasedcorrectrecognitionmorethanin-
elicited by each stimulus were scored manually and de- correct, χ2(1, N=26, 11.38, p≤.01) independently from
fined as the largest increase in conductance in a time thetypeoftaskχ2(1,N=26,1.21,p=.30).However,emo-
window from 1,500 to 4,000 ms after stimulus presenta- tional type showed significant effect χ2(1, N=26, 8.03,
tion (for the procedure see Amrhein, Muhlberger, Pauli, p≤.01).Post-hoccomparisons(standardizedresiduals)re-
& Wiedermann) [48]. Trials with artifacts were excluded vealed that anger, fear, surprise and happinesswerebetter
from analysis, whereas trials with no detectable response recognized than disgust, sadness and neutral faces (all
were scored as zero. The electrocardiogram was re- comparisonsp≤.01).
corded using electrodes on the left and right forearms. Aboutthevalenceattribution,ANOVAshowedasignifi-
Inter-beat intervals of the HR were converted to heart cant emotion (F(6, 25)=10.30, p≤.01, ɳ2=.38) and emo-
rate in beats per minute, to detect HR modulation dur- tion × condition effect (F(6, 25)=9.14, p≤.01, ɳ2=.38)
ing viewing stimuli. Trials with artifacts were excluded (Table 1). Post-hoc comparisons (contrast analysis, with
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Table1Self-reportmeasureofcorrectness(percentage),arousalandvalenceforeachemotionandcondition(faceand
script)
Self-reportrating Anger Fear Suprise Happiness Disgust Sadness Neutral
Face M (sd) M (sd) M (sd) M (sd) M (sd) M (sd) M (sd)
Correctness 89 1.34 91 2.87 84 1.89 80 2.09 69 1.98 65 1.56 64 1.22
Arousal 8.46 0.56 8.52 1.09 8.11 0.77 7.09 0.65 6.32 0.65 4.55 0.54 3.91 0.65
Valence 2.33 0.98 2.11 0.78 2.87 0.22 8.04 3.50 3.50 0.76 2.33 0.64 4.98 0.68
Script M (sd) M (sd) M (sd) M (sd) M (sd) M (sd) M (sd)
Correctness 86 2.33 88 3.98 85 2.87 77 2.09 74 1.98 67 2.09 60 2.09
Arousal 8.40 0.78 8.16 0.86 8.09 0.49 7.32 0.36 6.98 0.65 4.13 0.53 3.08 0.54
Valence 2.39 0.65 2.66 0.71 2.43 0.76 8.76 0.65 2.98 0.84 2.38 0.67 4.55 0.39
SAMratingnine-points(valence:1=highnegative,9=highpositive;arousal:1=low,9=high).
Bonferroni corrections for multiple comparisons) showed analyses, anger, fear surprise and happiness revealed in-
increased negative valence attribution for anger, fear, sur- creased HR in comparison with sadness, disgust and
priseand sadness in comparisonwithhappiness and neu- neutralstimuli.Moreover,disgustandsadnessshowedin-
tral face, as well as happiness was considered as more creased HR than neutral faces (all comparisons p≤.01)
positive than the other faces (all comparisons p≤.01). (Figure3).
Moreover, it was found a more negative attribution for
disgust in the case of script more than face condition EMG
F(1, 25)=10.79, p≤.01, ɳ2=.40). No other comparison ZygomaticEMGactivityrevealedsignificantdifferencesas
wasstatisticallysignificant(allcomparisonsp≥.01). a function of emotion (F(6, 25)=10.76, p≤.01, ɳ2=.41).
Aboutthearousalattributionitwasfound asignificant Asshownbycontrasteffects,EMGactivitywasenhanced
emotion(F(6,25)=10.15,p≤.01,ɳ2=.39)andemotion× in response to positive stimuli in comparison with nega-
condition effect (F(6, 25)=9.56, p≤.01, ɳ2=.37). Post- tiveandneutralfaces(allcomparisonsp≤.01).Contrarily,
hoccomparisonsshowedincreasedarousalattributionfor corrugator EMG activity was increased for negative emo-
anger,fear,andsurpriseincomparisonwithhappinessand tions, respectively anger, fear, and surprise in comparison
sadness (all paired comparisons p≤.01). Moreover all the with happiness, disgust, sadness and neutral stimuli (all
emotional faces were considered more arousing than comparisonsp≤.01)(Figure4and4b).
neutral faces (all paired comparisons p≥.01). In addition,
about the interaction effect, disgust was found as more Regressionanalysisbetweenvalenceandarousalratings
arousinginthecaseofscriptthanfaceconditionF(1,25)= andpsychophysiologicalmeasures
8.09, p≤.01, ɳ2=.33). No other comparison was statisti- Distinct stepwise multiple regression analyses were per-
callysignificant(allpairedcomparisonsp≥.01). formed for each psychophysiological measure and emo-
tion, considering the mean values for face and script
Psychophysiologicalmeasures condition. Predictor variables were arousal and valence
Successively, repeatedmeasureANOVAs,withtwo inde- ratings, and predicted variables were EMG, SCR, and HR
pendent repeated (within-subjects) factors (condition × amplitude for each emotion. We report in Table 2 the
emotion), were applied to each dependent measure cumulative multiple correlations between predictor
(SCR; HR;EMG). and predicted variables (R), cumulative proportion of
explainedvariance(R2),andtheregressionweights(β)for
SCR the regression equation at each step of the multivariate
ANOVA showed significant main effect of emotion (F(6, analysis.
25)=9.56, p≤.01, ɳ2=.37). As shown by contrast effects, As shown in Table 2, arousal and valence accounted
anger, fear and surprise revealed increased SCR in com- for the amplitudes of zygomatic muscle for happiness,
parisonwithhappiness,sadness,disgustandneutralstim- whereas mainly arousal rating accounted for corrugator
uli. Moreover, disgust and happiness showed higher SCR muscle for anger, fear and surprise. In addition, valence
thanneutralfaces(allcomparisonsp≤.01)(Figure2). and arousal explained the HR (increasing) more for
anger, fear, surprise, and happiness. Finally, SCR in-
HR creased response was mainly explained by the two pre-
ANOVA showed significant main effect of emotion (F dictors for anger, fear, and surprise, and secondly for
(6, 25)=10.98, p≤.01, ɳ2=.40). As shown by contrast disgustandhappiness.
Balconietal.BehavioralandBrainFunctions2014,10:32 Page8of14
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Figure2Mean(andSE)SCRmodulationsinresponsetodifferentemotions.
Discussion multimodal approach to study the specific domain of
The present study produced three major results, that we facial expression of emotions whereas other previous
summarizeinthefollowingpoints.First,therewasaclear research did not specifically consider this emotional
differentiation in children’ conceptualization (in terms of domain. Thirdly we considered the facial expression
arousal and valence) as a function of different emotions; of emotion with and without an emotional script con-
besides, the psychophysiological measures were highly text to study the contextual impact on face decoding.
modulated by emotional types, and arousal and valence Therefore the situated perspective was adopted in the
parameters accounted for the psychophysiological varia- present research.
tions in relationship with different emotional patterns; fi- As hypothesized by the dimensional approach to emo-
nally the presence of two different types of task – a facial tion [52,53], the representation of the emotional domain
expression decoding and a script comprehension –in- was based on a conceptual space defined by two exes,
duced significant differences in the subjective represen- arousal and hedonic value. In particular, the emotions
tations only for a limited number (mainly disgust) of with a high arousal level and a negative value were bet-
emotions. terunderstood,ifcomparedwithotheremotions.Specif-
For the first time we used multimodal measures to ex- ically, the emotions of fear, anger and surprise were well
plore the evaluation effect (based on valence and arousal) recognized and well labeled. A significant higher arous-
on psychophysiological behavior taking into account ing power was attributed to them, and these emotions
an ample range of emotions. Secondly we applied this were also considered as more negative. Moreover, they
Figure3Mean(andSE)HRmodulationsinresponsetodifferentemotions.
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Figure4Mean(andSE)(a)zygomaticand(b)corrugatormodulationsinresponsetodifferentemotions.
were better recognized than the other emotions, specific- indicated by previous researches [19,53,54]. In fact, not
ally in comparison with sadness and disgust. The positive only the hedonic category was systematically well repre-
emotionof happinesswasconsideredaslessarousingand sented,butitwascorrectlyidentifiedintermsofnegativity
more positively valenced and it was well represented and orpositivity.Moreover,arousalratingcanbeconsidereda
recognized. On the contrary, disgust appears to be more predictive cue of the ability to classify and differentiate
difficult to be identified, as well as sadness, and they both emotional correlates. Indeed, it was correctly used when
wereconsideredaslessarousingandlessnegative.Itshould the child was able to attribute an adequate label to the
beconsideredthatinpresentresearchweoptedtoevaluate emotion, while when the child cannot conceptualize the
the ability of subjects in spontaneously labelling the face/ emotion, the arousal value seems to be more ambiguous
script they saw. As revealed, disgust and sadness were not (forexamplefordisgust)orlessrelevant(sadness).
immediatelylabelled,butinmanycasestheywerecorrectly Asregardtomorenegativeandarousingemotions(fear,
described (using a semi-structured interview) only after a anger and surprise) some recent study [55,56] revealed
successive enquire. Therefore, the subjects showed a gen- high rates of recognition, that the researcher attributes to
eral ability in recognizing the two emotions, although this thecentraladaptivefunctionofthesenegativehigharous-
recognition was less immediate. It should be based on the ingemotions.Indeed,theyhasamainrolefortheindivid-
increased complexity to decode these emotions, because ual safeguard, both on an ontogenetic and a phylogenetic
theyarelearnedonlysuccessivelyincomparisonwithother level.Theymayberepresentedasacueinordertodetect
primaryemotions(suchasangerandfear). unfavorable environmental conditions [19,54]. Accord-
Therefore a first main result of the present study was ingly to the functional model [57,58], the emotional
that the dichotomy pleasure/displeasure and high/low expressionsrepresentaresponsetoaparticularevent,sig-
arousal was considered relevant by the subjects, confirm- nificant in terms of costs and benefits for people. Speci-
ing a significant role in emotion representation, as fically, the expression of anger and fear represents the
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Table2Stepwisemultipleregressions .b l.
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Anger Fear Surprise Happiness Sadness Disgust Neutral a h
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PMZRyrogedodmeiclatotirc Ar0o.11u3sal Va0le.22n8ce Ar0o.12u0sal Va0le.23n4ce Ar0o.12u2sal Va0le.23n3ce Ar0o.14u4sal Va0le.27n6ce Ar0o.11u8sal Va0le.23n0ce Ar0o.12u6sal Va0le.23n7ce Ar0o.11u4sal Va0le.22n6ce ioralandbrainfun vioralandBrain
c F
R2 0.01 0.07 0.04 0.09 0.04 0.11 0.19 0.57 0.03 0.09 0.06 0.03 0.01 0.06 tio un
β 0.20 0.21 0.24 0.23 0.15 0.11 0.34 0.28 0.15 0.18 0.23 0.26 0.23 0.20 ns.com ctions
stderror 0.21 0.22 0.15 0.17 0.21 0.28 0.18 0.27 0.23 0.20 0.17 0.19 0.18 0.26 2
t 1.02 0.87 0.95 0.88 0.78 0.70 1.76* 1.54* 0.77 0.84 0.96 0.87 0.67 0.59 /conte014,1
n0
Corrugator t/1:32
0
R 0.49 0.64 0.1=51 0.69 0.35 0.52 0.24 0.41 0.18 0.29 0.22 0.40 0.18 0.29 /1
/3
R2 0.24 0.40 0.26 0.47 0.12 0.27 0.05 0.18 0.03 0.07 0.04 0.18 0.03 0.07 2
β 0.31 0.32 0.23 0.21 0.27 0.20 0.23 0.28 0.32 0.38 0.36 0.29 0.20 0.23
stderror 0.25 0.20 0.20 0.18 0.18 0.19 0.33 0.34 0.30 0.28 0.22 0.27 0.17 0.20
t 1.88* 1.03 1.93* 1.02 1.43* 0.99 1.02 0.96 0.65 0.49 0.90 0.78 0.56 0.43
SCR
R 0.43 0.69 0.54 0.72 0.38 0.62 0.32 0.59 0.21 0.38 0.29 0.51 0.17 0.29
R2 0.18 0.47 0.27 0.51 0.13 0.41 0.38 0.34 0.04 0.14 0.07 0.25 0.03 0.08
β 0.18 0.28 0.22 0.20 0.18 0.23 0.29 0.20 0.34 0.35 0.35 0.57 0.27 0.33
stderror 0.11 0.17 0.28 0.26 0.20 0.21 0.21 0.30 0.30 0.30 0.26 0.23 0.22 0.29
t 1.80* 1.19* 1.97* 1.07 1.65* 1.17* 1.12* 1.15* 0.88 0.63 1.10* 1.08* 0.54 0.45
HR
R 0.42 0.70 0.50 0.80 0.44 0.71 0.36 0.65 0.22 0.38 0.35 0.67 0.18 0.29
R2 0.17 0.49 0.25 0.64 0.19 0.50 0.14 0.42 0.04 0.14 0.12 0.36 0.03 0.08
β 0.17 0.20 0.20 0.22 0.28 0.27 0.29 0.27 0.19 0.34 0.25 0.22 0.39 0.28
stderror 0.22 0.26 0.18 0.15 0.20 0.21 0.32 0.30 0.15 0.18 0.18 0.29 0.27 0.22
t 1.84* 1.14* 1.98* 1.18* 1.90* 1.09* 1.12* 1.10* 0.67 0.78 1.55* 1.12* 0.77 0.60
Arousalandvalenceaspredictorvariables,pshychophysiologicalmeasuresaspredictedvariables.
*=P≤.05. Pa
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