Four-month-old infants’ emotional communication towards familiar and unfamiliar social partners

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FACULTEIT DER MAATSCHAPPIJ- EN GEDRAGSWETENSCHAPPEN Graduate School of Childhood Development and Education

Four-month-old Infants’ Emotional Communication towards Familiar and Unfamiliar Social Partners

Masterscriptie Orthopedagogiek Pedagogische en Onderwijskundige Wetenschappen Universiteit van Amsterdam

Naam: Laura van Dam Begeleiding: Dr. C. Colonnesi & drs. E. A. Salvadori Amsterdam, 1 February 2019

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Table of contents

Abstract ... 3

Introduction ... 4

Single behaviors of (intrapersonal) emotional communication ... 4

Co-occurrence of (intrapersonal) emotional communication behavior... 4

Infants’ emotional communication with familiar and unfamiliar social partner ... 6

Dyadic and triadic social interactions ... 6

Influence of demographic factors ... 7

Social and scientific relevance ... 8

Present study ... 9 Method ... 10 Participants ... 10 Procedure ... 12 Socio-Demographics Questionnaires ... 12 Coding behaviors ... 12 Gaze. ... 12 Facial expressions. ... 13

Vocalizations and verbalizations. ... 13

Co-occurrence of 2 and 3 behaviors of the infant ... 13

Gaze and facial expressions: ... 13

Gaze, facial expressions and vocalizations: ... 13

Outcome variables... 13

Inter-rater reliability ... 14

Analytic Strategy & Preliminary Analyses ... 14

Results ... 15

Emotional communication behaviors during dyadic interactions... 15

Infant’s emotional communication: single behaviors ... 15

Infant’s emotional communication: co-occurrence behaviors ... 18

Emotional communication behaviors during triadic interaction ... 19

Infant’s emotional communication: single behaviors ... 20

Infant’s emotional communication: co-occurrence behaviors ... 22

The influence of demographic factors in emotional communication of the infant. ... 23

Dyadic Interactions ... 23

Triadic interactions ... 26

Discussion ... 29

Emotional communication of the child towards the social partner during dyadic interactions ... 29

Emotional communication of the child towards the social partner during triadic interactions ... 30

Emotional communication of the infant towards the social partner and the effect of demographic factors ... 31

Limitations... 32

Conclusion ... 32

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Abstract

The current study aimed at investigating the differences in infants’ emotional communication towards familiar social partners (i.e., mothers and fathers) and unfamiliar social partner (i.e., female experimenter) at four months of age. Infants’ emotional

communication consists of eye gaze, facial expressions of emotions, and vocalizations. This early form of nonverbal communication is very important for later development of socio-communicative functioning, for example Theory of Mind. The present study was part of a larger longitudinal study, and the sample consisted of 34 infants, each observed while

interacting for four minutes with their mothers, fathers, and experimenter, independently. The dyadic and triadic interactions were semi-structured at the family’ houses, and recorded with a 360 camera and micro-coded with the Observer XT 13.0. Repeated measures ANOVA’s were performed in order to examine the infant’s behaviors with the different social partners.

Accordingly, 4-month-old infants resulted to show more positive and negative emotional communication towards the familiar social partners than towards the unfamiliar social

partners, confirming the existence of differences in infants’ early emotional communication in different interactional contexts. In addition, results suggested that infants’ emotional

communication is influenced by gender, premature birth and socio-economic status of the parents. Shedding light on infants’ early emotional communication seems paramount to fully understand which mechanisms influence children’s early socio-communicative development.

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Four-month-old Infants’ Emotional Communication towards Familiar and Unfamiliar Social Partners

Introduction

Infants are babies whom are not able to speak and before they learn how to verbally communicate with another, they are able to engage in social interactions with familiar social partners and unfamiliar social partners. In the first 4 months of their live infants develop more non-verbal communication to engage with their social partner (Henning, Striano & Lieven, 2005).

Single behaviors of (intrapersonal) emotional communication

Infants’ emotional communication is the first type of nonverbal communication that human infants develop. Three are the main preverbal behaviors that infants use in order to engage in social interactions: eye gaze, facial expressions of emotions and vocalizations. Gaze refers to the infant’s direction of attention, the visual attention to the social partners face (Lavelli & Fogel, 2005); facial expressions indicate the affective internal state of the infant, and are displayed on a range from positive (e.g., smile) to negative (e.g., frowning) valence; vocalizations consist in verbal attempts of communication with the social partner. The ability to coordinate these three communicative modalities has been referred to as emotional

communication (Yale, Messinger, Cobo-Lewis, Oller, & Eilers, 1999; Yale, Messinger, Cobo-Lewis, & Delgado, 2003; Lavelli & Fogel, 2005; Colonnesi, Zijlstra, van der Zande, & Bögels, 2012), and it is important for the social communicative development later in life, as for instance for forming the foundation of the communication about an external object or event, or additionally, for developing Theory of Mind skills (Colonnesi, Rieffe, Peruchini & Koops, 2008).

Co-occurrence of (intrapersonal) emotional communication behavior

Although most of the studies focused on infant-mother interaction, there are different studies that investigated not only infants’ use of the single emotional communication behavior (i.e., gaze, facial expressions or vocalizations) but also the co-occurrence of these behaviors. For example, Yale et al. (1999) investigated longitudinally infants’ coordination of facial expressions and vocalizations in the interaction with their mother at 3- and 6- months of age. They used an event-based analysis to investigate the coordination of these two behaviors even when they don’t overlap completely. It can be that the infant starts smiling and vocalize and end the coordination with smiling. They found through this event-based perspective that 3-

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and 6-months old infants coordinated vocalizations and facial expressions systematically in the interaction with their mothers. The infants use the facial expressions together with the vocalizations but were ending their vocalization before their facial expressions. Yale et al. (2003) further explored the use of this coordination by investigating whether young infants of 3- and 6- months old coordinate the different preverbal behaviors in specific patterns while interaction with the mother. In order to explore infants’ preverbal interactive and expressive competences, they looked at how the three emotional modalities occur during face-to-face interactions. They found that infants of 3- and 6- months of age in their coordinate positive and negative facial expressions with vocalizations and with gaze towards their mothers. In light of the special coordinated patterns the authors found that vocalizations begin and end with a smile or a frown. Infant’s gaze combined with smiles or frowns were more coordinated when the infants is 6-months-old compared to 3-month-old. The socio-communicative

development of 3-months-old and 6-month-old infants give more information both on the early emotional regulation and the early development of intentional communication (Yale et al., 2003).

Another study by Lavelli and Fogel (2005) investigated the temporal co-occurrences of infants’ gaze with facial expressions and vocalizations during interactions with their mothers. They found that the 2nd_{month of age is a period of change in infant’s development}

of attention and emotion and the beginning of a relation between the mother’s visual attention to the infant and the infant’s emotions to the mother. This relation establishes more during the 3rd_{month and becomes more playful and the relation of attention and emotion becomes more}

important. The studies above show the co-occurrence of the single behaviors of emotional communication and the importance of the use of this behavior for the emotional development of infants. The studies investigate the face-to-face interaction between the infant and the mother. Unlike these studies, Colonnesi et al. (2012) investigate the co-occurrence of the single behaviors of emotional communication during a face-to-face interaction with the mother and the father. In line with other research, they found that vocalizations and positive facial expressions are produced in combination with gaze to the mother and father parent. The vocalizations occur in combination with positive and negative facial expressions. An

interesting founding is that they found the coordination of the three behaviors. They found that infants vocalize the most, when they show positive facial expressions during gaze at the parent.

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Infants’ emotional communication with familiar and unfamiliar social partner

Infants do not only interact with their parents in their daily lives. Indeed, over development, they increasingly engage in social interactions with unfamiliar others (Lin & Green, 2009; Jaffe, Beebe, Feldstein, Crown, & Jasnow, 2001). Whereas abundant research has investigated the face-to-face interaction between infants and mothers (see studies reported above), very little is known about interaction patterns with fathers, and even less with stranger people. For example, infants are more inclined to show positive feelings and to gaze towards their mothers when compared with the fathers. Infants also produced more vocalizations combined with positive facial expressions towards their mothers than towards fathers

(Colonnesi et al., 2012). Jaffe et al. (2001) investigate face-to-face interaction between infants and an unfamiliar person, paying particular attention to their vocal rhythms. They found that 4-month-old infants differentiate in their vocal rhythms between the interaction with their mother or with the unfamiliar person. Infants show more vocalizations with the unfamiliar person in the lab compared with the mother at home. Infants turned away more during the interaction with the unfamiliar person compared to the interaction with the mother. Also, Lin and Green (2009) investigated the use of infant’s emotional communication behaviors between the interaction with the familiar social partner (i.e., mothers) and the unfamiliar social partner. They reported that 10-month-old infants used fewer smiles and spent significantly less time looking towards the unfamiliar person than the 4-month-old infants, when observed during face-to-face interactions, meaning that younger infants display more interest and emotionality towards unfamiliar others than older infants. At all ages (i.e., 4, 7, and 10 months) the infants show more smiles during the interaction with the unfamiliar person than they did with their mothers.

Dyadic and triadic social interactions

Infants use emotional communication to engage both in dyadic and triadic interactions (Striano & Stahl, 2005). Specifically, whereas dyadic interactions refer to face to face

interactions and triadic interactions refers to those interactions in which there is an object involved. While dyadic interactions mainly consist of emotional and affective aspects, triadic interactions extend to the interest of the body and concern the use of symbols, allowing the infant and the social partner to share intentions and meaning (Aureli, Presaghi & Carito, 2017). More specifically, at 4 months of age, infants reach a peak of interest in face-to-face communication; afterwards they increase develop interest for third objects (or events, or people) beyond the mere infant-adult interaction. Triadic interactions are important for

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children’s later development, as for example to language learning and imitation skills (Striano & Stahl, 2005). Striano and Stahl (2005) investigated for the first-time infants’ sensitivity to triadic interactions before nine months of age, by carrying out two studies in the same article. They demonstrated that 3-month-old infants are already likely to follow the gaze of the adult towards an object. In the second study they found that 3-month-old infants are sensitive for an object and sharing attention. They found that 3-month-old infants when the dyadic interaction is broken and a triadic interaction is started shown more attention and positive affect. They refer to Hobson’s (2002) theory of ‘relatedness triangle’. It refers to the importance of the infant’s emotional engagement with the social partner. Striano and Stahl (2005) wrote that when this ‘relatedness triangle’ is completed, infants’ gaze and smiles are the same in a triadic interaction compared to a dyadic interaction.

Aureli et al. (2017) also investigated the differences in mother-infant’s communication patterns during dyadic and triadic interactions in a longitudinal study. Adopting Fogel et al. (2003)’s coding system, they explored unilateral, asymmetrical and symmetrical

communication patterns during 80 mother-infant interactions when the infant is 4 and 6 months old. Accordingly, unilateral communication pattern describes the event in which only one partner tries to engage with the other. A symmetrical pattern relies on mother and infant mutual engagement, and the a-symmetrical pattern means that one partner is attending to the other, gathering attention, but without responding. Findings revealed that during dyadic interactions at 4 months, the unilateral pattern prevailed. For the triadic interaction at 4 and 6 months, they found the symmetrical pattern prevailed the most. Taken together, results suggest that the infant and the mother learn how to gradually engage with one another, adjusting to their social interaction partner.

Influence of demographic factors

Infants communicative behaviors, namely gaze, facial expressions, and vocalizations, and the way the use these to engage in social interactions with their social partners, can be dependent on different demographic factors. Whereas infants’ gender seems not to predict their use of emotional communication towards their parents (Aureli et al., 2017; Cerezo, Sierra-García, Pons-Salvador, & Trenado, 2017; Colonnesi et al., 2012), a recent study from Cerezo et al. (2017) showed that parents’ gender seems to have an effect. The authors tested 52 infants aged 6 up to 10 months of age during dyadic interactions with their parents. They found that fathers were more active in their interactions than mothers. Indeed, the maternal dyad interaction was more repetitive than the father dyad interaction. Besides gender, also

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preterm birth is considered to be a factor that affects the emotional communication. A premature birth is referred to when the child is born to a pregnancy shorter than 37 weeks. A very premature birth is a birth during a pregnancy shorter than 32 weeks. (Van der Pal & Van der Pal - de Bruin, 2012). Despites there is better medical care and the pre-term infants have better change on survival, there is an impact on their developmental domains such as

problems in language development or mental retardation. A low birth weight and neonatal complications can influence the social-communicative abilities of the preterm infant. They are less responsive and active during the interaction with their caregiver (De Groote, Roeyers, & Warreyn, 2006). De Schuymer, de Groote, Striano, Stahl and Roeyers, (2011) investigated the use of emotional communication of 3, 6, and 9- month old preterm and full-term infants during the dyadic and triadic interaction. They didn’t find any significant difference during the use of emotional communication during the dyadic and triadic interaction but they found some differences. They found in the comparison at 6 months, namely that 6-month-old preterm infants show less positive affect during the still-face and they found one difference at 9 months and that is that the preterm infants followed gaze less than the full-term infants.

In addition, the family’s socio-economic status (SES) is also a factor that influences infants’ communication. There has been a lot of research about the relation of low SES and language development of the infant. Low SES and the stimulation of language development are related to each other (Bradley & Caldwell, 1984). In families with low SES there is less verbal interaction which contributes to a less good language development of the child compared to families where there is a rich verbal interaction (Brockmeyer et al., 2012).

Social and scientific relevance

Whereas there is abundant information about the mother-infant’s emotional

communication and interactive dynamics, literature describing such with father-infant dyads is not yet exhaustive, and research investigating unfamiliar social partner-infant dyads is even less present. To our knowledge there is no literature available that describes the use of

emotional communication of the infant towards the familiar social partner and the unfamiliar social partner during a triadic interaction. For this research it is interesting to investigate the difference in emotional communication between the familiar partner and the unfamiliar partner. This because it helps us scientifically to find more results for this topic. It teaches us more about the communicational development of infants and the way they communicate with their social partners.

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Because there is to our knowledge less research about the demographic factors that could be influencing the emotional communication, in this research there will be four factors that are exploratory investigated. More information about this topic helps us to give

recommendations for the clinical sector about the social-emotional development of children.

Present study

Accordingly, the aim of the present study was to investigate 4-month-old infants emotional communication, investigating differences with their mothers and fathers (familiar social partner) and the experimenter (an unfamiliar social partner), during dyadic and triadic (i.e., with an age-appropriate toy) face-to-face interactions. Studies investigating triadic interactions already at 4 months are very rare (e.g., Aureli et al., 2017; Striano & Stahl, 2005), and the current research adds original contributes to early emotional communication investigated with regards to also unfamiliar social partners. The present study aims to expand Colonnesi et al., (2012)’s results to triadic interactions, between the mother, the father and also an unfamiliar person. Colonnesi et al. (2012) presumed that there are differences in interaction between gender of the infant and gender of the parents. However, they did not find evidence to confirm such hypothesis. Maybe in this research such evidence can be found. The demographic factors are explorative for further research.

Based on previous knowledge and literature, the current study addressed three main research questions:

I) Do 4-month-old infants differ in the way they communicate to unfamiliar (i.e., female experimenter) and familiar (i.e., mothers and fathers) social interaction partners, during dyadic interactions?

Specific sub hypotheses are: a) Infants gaze longer at mothers and fathers than towards the experimenter; b) Infants smile shorter at mothers and fathers than at the experimenter (Lin and Green, 2009); c) Infants vocalize more often with mothers and fathers than with the experimenter person; d) the three behaviors of emotional communication occur more during the interaction with mother and father than towards the experimenter (Colonnesi et al., 2012).

II) Do 4-month-old infants differ in the way the communicate to unfamiliar (i.e., experimenter) and familiar (i.e., mothers and fathers) social interaction partners, during triadic interactions?

Specific sub hypotheses are: a) Infants gaze longer at mother (Aureli et al., 2017); b) infants smile longer at mothers than to fathers and the experimenter; c) infants vocalize more to

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mothers; d) the three behaviors of emotional communication occur more during the interaction with mother and father than towards the experimenter.

III) To what extend do child-related and parent-related demographics factors affect

4-month-old infants’ emotional communication towards the mother, father and experimenter?

Specific sub hypotheses are: a) Girls show more emotional communication than boys; b) premature infants show more negative emotional communication (e.g., De Groote et al., 2006; De Schuymer et al., 2011); c) Infants of parents with a high income show more emotional communication (Brockmeyer et al., 2012); d) infants of parents with a scientific education level show more emotional communication (Brockmeyer et al., 2012; Bradley & Caldwell, 1984).

Method Participants

Thirty-four families participated in the present study, when their infants (16 girls, 47.1% and 18 boys, 52.9%) were 4-month-old (Mage: 3.74 months (SD = .45), range = 3 – 4 months. The

cohort of the current study is a subsample of an ongoing longitudinal study on children’s emotional and social development. The families were recruited via flyering in kinder gardens, childcare centers, schools, consultative bureaus and trough social media. Out of the 34

infants, three were prematurely born (8.8%), Mage = 34 weeks (SD = .29). Parents ‘average

age was 33.48 years (SD = 3.02, range of age = 28-40 years), for mothers, and 36.75 years (SD = 4.12, range of age = 31 – 47 years) for fathers. Table 1 gives an overview of the demographics of the parents (i.e., country of birth, education level, current professional level and income). The social economic status (SES) of this subsample was above average

according to the Central Bureau for Statistics (CBS). The present study and the broader research of which it is part was approved by the ethical commission of the University of Amsterdam by number 2016-CDE-7403.

Table 1

Demographic data of the participants expressed in percentages

Characteristic Mother (n = 33) Father (n = 32) Country of Birth Netherlands 79.4 73.5 Europe 11.8 11.8

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US 2.9 2.9

Other 2.9 2.9

Highest education level

Primary education 0 0

Primary professional education (LBO) 0 2.9

Secondary education (MAVO) 2.9 5.9

Higher secondary education (HAVO) 2.9 0

Secondary scientific education (VWO) 0 0

Secondary professional education (MBO) 2.9 8.8

Higher professional education (HBO) 35.3 26.5

Higher scientific education (University) 44.1 44.1

Otherwise, specify 8.8 5.9

Current Professional level

Never been employed 0 0

Mainly manual labor without professional training 0 0 Mainly manual labor requiring professional training 2.9 0 Mainly brain labor requiring professional training 2.9 11.8 Mainly brain labor at primary or secondary professional education

level (LBO or MBO) and not in an executive function

0 0

Self-employed person with maximally 4 employees 2.9 8.8 Self-employed person with more than 4 employees 2.9 5.9 In paid employment at primary or secondary professional

education level (LBO or MBO) and not in an executive function

2.9 14.7

In paid employment at higher professional education level (HBO) and in an executive function

41.1 23.5 In paid employment that requires a scientific education

(university) 41.2 29.4 Income < 500 euro 14.7 0 500 – 1000 euro 2.9 0 1000 – 2000 euro 17.6 5.9 2000 – 3000 euro 14.7 29.4 3000 – 4000 euro 26.5 17.6

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4000 – 5000 euro 2.9 14.7 > 5000 euro 14.7 17.6 I don’t know 0 0 I don’t want to say 0 8.8

Procedure

Children were observed during one-hour home-visit. In face-to-face settings infants were independently observed with their mothers, their fathers and an unfamiliar person (the female experimenter). Each interaction lasted 4 minutes and consisted of two parts. The first two minutes were a dyadic interaction between the infant and the adult social partner and the second two minutes were a triadic interaction between the infant and the social partner with a toy (i.e., a luminous ball).

The social interactions were recorded with a 360 Samsung Camera. We use the observer software (Observer XT 13.0 (Noldus, 2009) in order to systematically micro-code the emotional behaviors we frame by frame (< 1second). The coding of the child and the adult has been done separately by two coders. The Observer XT is often been used in infant studies because this program makes it possible to code infant and adult behavior accurately and efficiently (Noldus, 2009).

Socio-Demographics Questionnaires

Two weeks before the home visit the parents received a link to an online questionnaire about some demographic’s factors like income, education, day of birth, siblings’ etcetera. These questionnaires are used to test the effect of some demographics.

Coding behaviors

The three main behaviors, namely gaze, facial expressions (e.g., positive and negative) and vocalizations were independently coded during the dyadic and triadic observation at 4 months. To code the different behaviors a coding system for the child and adult was

developed by the researchers of the longitudinal My-BEST study. The Observer XT software allows coding the duration of the behavior as a state event (i.e., duration in seconds, with a starting and an ending) and as a point event (frequency of occurrences).

Gaze. Gaze was coded as a state event and divided in four categories. 1) Gaze towards

the infant and adult, looking towards the infant’s or adult’s face, hands or body. 2) Gaze to the proximal toy during the triadic interaction. 3) Gaze elsewhere, the infant or adult is looking away towards something else, 4) Not visible, when the gazing is not visible.

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Facial expressions. Facial expressions were coded as a state event and divided in four

categories; 1) Positive facial expressions (e.g., smile, raising up their lips, possible combined with raising up their cheeks), 2) negative facial expressions (e.g., infant frowns the eyebrows and is fussy and starts to cry). 3) Neutral, infants show no expression in the face, there is no muscle movement and 4) not visible. The positive and negative facial expressions of the infant and adult are coded with an intensity scale of low, moderate and high intensity, which was however not investigated in the present study.

Vocalizations and verbalizations. Infants’ verbal attempts to communicate with the

adult (e.g., syllables, squeals, babbling) were identified as vocalizations, and coded as point event. Vocalizations of the infants are. Adult verbalizations to the infant was coded as state event.

Co-occurrence of 2 and 3 behaviors of the infant

To examine which modalities of emotional communication the infants shows during the interaction with the familiar and unfamiliar social partner a few data profiles were conducted.

Gaze and facial expressions: This data profile showed the positive and negative

facial of the infant expressions while gazing towards the familiar and unfamiliar social partner.

Gaze, facial expressions and vocalizations: This data profile gave the co-occurrence

of the three behaviors of emotional communication the infants showed during the interaction with the familiar and unfamiliar social partner. Two data profiles were made, the first one was gaze, positive facial expressions and vocalizations and the second one was gaze, negative facial expressions and vocalizations.

Outcome variables

The variables that were used in the analyses are proportions for the single behaviors of gaze and facial expressions because it is the duration of the behavior. The vocalizations were corrected frequencies. For the co-occurrence of gaze and facial expressions the duration of this behavior was used so these were corrected proportions and for gaze and vocalizations and for the co-occurrence of the three behaviors of emotional communication (i.e., gaze, facial expressions and vocalizations) corrected frequencies were used in the analysis and for the vocalizations the frequencies were used.

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Inter-rater reliability

Two groups consisting of 3 master students each coded the sample + adult and

children by different coders. The reliability was calculated with Cohen’s Kappa on 11 videos (18% of the sample).

Analytic Strategy & Preliminary Analyses

To calculate how many participants were necessary for the study, at priori power analyses were performed. G*power statistics softer was consulted, an analysis program that is used for various statistical tests in social, behavioral, and medical sciences (Faul, Erdefelder, Buchner, & Lang, 2009). According to the power calculation (Alpha = 0.05, Effect size = 0.5) a minimum sample size of 51 participants was required. Although aware of not meeting such criteria, for the purpose of the present thesis analyses were still conducted.

Repeated measures ANOVAs were performed in order to account for the dependency of the observations while determining whether there are significant differences in infants’ emotional behaviors when engaging with mothers, or fathers or the unfamiliar person. Emotional behaviors were analyzed independently for social gaze, positive/negative facial expressions, and vocalizations and the co-occurrence of these behaviors. The within-subject factor was the social partner (i.e., mother, father or experimenter) infants interacted with. In order to determine whether there was a significant difference of infants’ sex, premature birth, parents’ income and education level, each of the mentioned variable was insert in explorative models as between-subject factor. Sidak Post-Hoc is used because of the power of the sample. Sidak Post-Hoc is less conservative compared to the Bonferroni. The referred category for the post-hoc comparisons in the final analyses was the experimenter. In order to find some

cohesion between the different behaviors of emotional communication of the infant a non-parametric correlation test Spearman’s Rho (rs) was conducted.

Prior to running the main analyses, preliminary analyses were conducted to check assumptions. With regards to the dyadic interactions data, outliers’ inspections of the data were carried out with boxplots, which spotted the presence of seven univariate in the data of negative facial expressions of the child towards mother, father and experimenter. With regards to the triadic interactions data, also outliers’ inspections of the data were carried out with boxplots, which spotted some outliers. There was one outlier in the data of gaze towards the mother, one outlier in the data of negative facial expressions to the mother, three outliers with father and two outliers with the experimenter. There was one outlier in the data of the positive facial expression of the child towards the experimenter and for vocalization there is

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one outlier with mother, one with father and one with the experimenter. Outliers were not correct for in the current project, in order to protect the original integrity of the data and do not alternate interpretation of the results. Investigation of the assumption of normality

suggested a significant deviation from it, with data mostly skewed to the left. For the purpose of the current thesis, no transformations were applied.

Results

Emotional communication behaviors during dyadic interactions

Descriptive statistics about the behaviors of emotional communication during dyadic interaction are displayed in Table 2.

Table 2.

Descriptive statistics dyadic interaction (Means and Standard Deviations) Child emotional communication Mother (n = 28) Father (n = 28) Experimenter (n = 28) Single behaviors M SD M SD M SD Gaze to Adult .79 .19 .74 .21 .77 .18

Positive Facial expressions .23 .19 .20 .15 .20 .17 Negative facial expressions .09 .15 .05 .07 .03 .09

Vocalizations 11.58 8.79 9.63 7.37 7.99 6.80

(n = 32) (n = 33) (n = 31)

Co-occurrence behavior M SD M SD M SD

Gaze & Positive facial expressions

.21 .18 .19 .18 .20 .15

Gaze & Negative facial expressions

.07 .13 .05 .10 .01 .03

Gaze, Positive facial expressions & Vocalizations

3.29 3.31 1.91 2.42 3.26 4.12

Gaze, Negative facial expressions &

Vocalizations

1.78 3.54 1.05 2.51 .25 .67

Infant’s emotional communication: single behaviors

In order to explore relations among the different behaviors of emotional

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conducted. The spearman’s Rho is used because the data of the sample is not normal distributed (Field, 2009). The Spearman’s Rho correlations are shown in Table 3. Table 3.

Spearman’s Rho (rs) correlation between the different emotional communication behaviors of

the infant during the dyadic interaction. Child & Social partner &

emotional communication

Gaze Positive facial expressions

Negative facial expressions

Vocalizations Dyadic interaction

Child & Mother

Gaze X .188 -.095 -.179

Positive facial expressions - X -.033 -.028

Negative facial expressions - - X .712**

Vocalizations - - - X

Child & Father

Gaze X .195 -.257 -.294

Positive facial expressions - X -.522** -.308

Child & Experimenter

Gaze X -.181 -.181 -.295

Positive facial expressions - X -.142 .445*

Negative facial expressions - - X .232

* p <.05 ** p <.01

Accordingly, to the Spearman’s Rho correlations test there are some significant relations between the single behaviors. Between the negative facial expressions of the infant and vocalizations to the mother a strong significant positive correlation was found (rs (28) =

.71 p = <.001). When the infant has negative facial expressions there are also more vocalizations.

Between positive facial expressions and negative facial expressions of the infant to the mother a negative moderate significant correlation (rs (28) = -.522, p = .002) has been found.

This cohesion shows that when the infant shows more positive facial expressions towards the father there are less negative facial expressions.

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A positive moderate significant correlation between negative facial expressions and vocalizations of the infant to the father had been found. This correlation between these behaviors is significant (rs (28) = -.518, p = .002). When the child shows negative facial

expressions, the vocalizations will increase.

A moderate significant correlation had been found between the positive facial

expressions of the infant to the experimenter and vocalizations (rs (28) = .445, p = .012). This

means that when the infant shows positive facial expressions during the interaction with the experimenter, the vocalizations of the infant increases.

In order to explore these relations between the different single behaviors of the infant to the familiar and unfamiliar partner a repeated measures ANOVA was conducted. The results of the repeated measures are shown below, with regards to the Greenhouse-Geisser correction, because the assumption of sphericity has been violated. The Greenhouse-Geiser is used because this gives a correction factor that is applied to the rise to a correction factor that is applied to the degrees of freedom used to assess the observed F-ratio. Because of this, two numbers of degrees of freedoms is used. The correction is more conservative, that’s why this one is used. (Field, 2009).

The results of gaze as a single behavior to the social interaction partner shown that infants’ gaze does not differ among the different social partner, F (1.56, 42.06) = .567, p = .53. The infant gaze longer to mother and experimenter as shown in Figure 1.

The results about the positive facial expressions (e.g., smile, raising up their lips, possible combined with raising up their cheeks) of the infant to the social interaction partner are not significant F (1.88, 50.98) = .275, p = .74. The results shown that despite it isn’t significant infants show more positive facial expressions towards the mother. The results about the negative facial expressions (e.g., infant frowns the eyebrows and is fussy and starts to cry) of the infant to the social interaction partner are also not significant F (1.73, 46.78) = .291, p = .07. Infants show more negative facial expressions to mother and father than towards the unfamiliar social partner.

The results about vocalizations of the infant to the social interaction partner are not significant F (1.78, 48.17) = 2.262, p = .12. For the vocalizations counts the same as for negative facial expressions. The infants show more vocalizations towards the mother and father.

There are no significant results for the use of the single behavior of emotional communication of the infant to the different social interaction partners. In Figure 1 is shown that infants show the most single behavior towards the mother compared with father and

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experimenter. Infants gaze longer to the experimenter compared to father and shown more positive facial expressions towards the experimenter then towards father.

Figure 1. Emotional communication of the infant: Single behavior

Infant’s emotional communication: co-occurrence behaviors

To investigate the research, question a repeated measure was conducted between co-occurrence of the different behaviors. The behaviors that have been used were: a) gaze and facial expressions, namely the times the infant gazes towards the social partner with positive facial expressions, on the one hand, and the time the infant gaze to the social partner with negative facial expressions, on the other hand, and b) the co-occurrence of the three behaviors (i.e., gaze, positive facial expressions and vocalizations, on the one hand, and gaze, negative facial expressions and vocalizations, on the other hand) during the dyadic interaction has been measured.

The results of the co-occurrence of gaze and positive facial expressions are not significant F (1.83, 49.52) = .595, p = .54. The results about the co-occurrence of gaze and negative facial expressions during the dyadic interaction are significant F (1.27, 34.38) = 4.37, p = .04. The infant uses more gaze and negative facial expressions simultaneously with mother compared with the experimenter.

The results of the co-occurrence of the three behaviors (i.e. gaze, facial expressions and vocalizations) at the same time shown that the use of positive emotional communication (i.e., gaze, positive facial expressions and vocalizations) was not significant F (1.89, 51.23) =

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.984, p = .38. The co-occurrence of gaze, negative facial expressions and vocalizations is significant F (1.19, 4.111) = 4.11, p = .05.

As shown in Figure 2 the infants show more co-occurrence of behavior to the mother then to the father or experimenter. The infants use more positive emotional communication (i.e. gaze, positive facial expressions and vocalizations) towards the mother and experimenter then to the father. For the co-occurrence of gaze and negative facial expressions and gaze, negative facial expressions and vocalizations the infants show this more to mother and father then to the experimenter.

Figure 2. Emotional communication of the infant: Co-occurence behavior.

Emotional communication behaviors during triadic interaction

Descriptive statistics of the behaviors of the child during the triadic interaction are showed in Table 4.

Table 4. Descriptive statistics triadic interaction (Means and Standard Deviations) Child emotional communication Mother (n = 27) Father (n = 27) Experimenter (n = 27) Single behaviors M SD M SD M SD Gaze to Adult .18 .13 .20 .13 .22 .13

Positive Facial expressions .08 .09 .05 .04 .08 .14 Negative facial expressions .03 .05 .03 .07 .02 .04

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Vocalizations 3.05 4.72 2.80 3.79 2.92 6.30 (n = 30) (n = 33) (n = 32)

Co-occurrence behavior M SD M SD M SD

Gaze & Positive facial expressions

.03 .05 .03 .04 .04 .05

Gaze & Negative facial expressions

.01 .02 .01 .03 .01 .01

Gaze, Positive facial expressions & Vocalizations

.26 .44 .21 .59 .21 .54

Gaze, Negative facial expressions &

Vocalizations

.07 .25 .29 .99 .09 .37

Infant’s emotional communication: single behaviors

To find out if there is cohesion between the three behaviors of emotional

communication in the triadic interaction of the infant with the social partner the correlation has been tested with the non-parametric correlation test Spearman’s Rho (rs). The outcomes of

these test are shown in Table 5. Table 5

Spearman’s Rho (rs) correlation between the different emotional communication behaviors of the infant during the triadic interaction.

Child & Social partner & emotional communication

Gaze Positive facial expressions

Negative facial expressions

Vocalizations Child & Mother

Gaze X .275 .310 .031

Positive facial expressions - X .096 .291

Child & Father

Gaze X .276 .212 .183

Positive facial expressions - X .029 .154

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Child & Experimenter

Gaze X .331 .186 -.131

Positive facial expressions - X .095 .543**

* p <.05 ** p <.01

The significant results of this correlation test are written below. This correlation of the single behaviors has been done to explore relations between the single behaviors of emotional communication. Negative facial expressions and vocalizations infants use to father are

moderate and significant correlated to each other (rs (27) = .522, p = .002) and means that

when the child shows negative facial expressions the vocalizations increase.

Between positive facial expressions and vocalization of the infant to the experimenter, the correlation is moderate significant (rs (27) = .543, p = .001).

In order to explore these relations between the different single behaviors of the infant to the familiar and unfamiliar partner a repeated measures ANOVA was conducted. The mother, father and experimenter were the within factor.

The results of the ANOVA’s for the use of gaze of the infant towards the adult is not significant F (1.84, 47.78) = 1.146, p = .32.

The use of positive facial expressions of the infant towards the social partner is not significant F (1.75, 45.46) = 1.078, p = .34. The use of negative facial expressions of the infant there is no significant outcome F (1.87, 48.65) = .521, p = .58. Infants show more negative facial expressions to the father then to mother and the experimenter.

The use of vocalizations of the infant to the social partner is not significant different F (1.85, 48.09) = .025, p = .97. Infants vocalize the most to the mother during the triadic interaction.

As shown in Figure 3 the use of the single behaviors of the infant is different

compared to the use of this single behavior in the dyadic interaction. Infants gaze longer and show more positive facial expressions to the experimenter then to the mother and father.

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Figure 3. Emotional communication of the infant: Single behavior.

Infant’s emotional communication: co-occurrence behaviors

A repeated measure has been conducted to see for any significance between the co-occurrence of emotional communication behavior and the social partner during the triadic interaction. The use of gaze and positive facial expressions of the child during the triadic interaction are not significant F (1.98, 51.61) = 1.743, p = .19. As shown in Figure 4 infants shown more positive facial expressions while gazing to the experimenter compared to mother and father. The use of gaze and negative facial expressions is also not significant F (1.63, 42.37) = .697, p = .48. The infants show more negative facial expressions while gazing to the father. The co-occurrence of the three behaviors at the same time is also not significant. The result of the use of gaze, positive facial expressions and vocalizations is F (1.81, 47.11) = .038, p = .95. The infants show the most emotional communication to the mother as shown in Figure 4. The use of gaze, negative facial expressions and vocalizations is not significant F (1.04, 27.15) = 1.513, p = .23. Figure 4 show that infants use gaze, negative facial expressions and vocalizations the most towards the father.

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Figure 4. Emotional communication of the infant: Co-occurence behavior.

The influence of demographic factors in emotional communication of the infant. Dyadic Interactions

In order to test the third hypothesis, namely the influence of gender, prematurity, income of the parents and education level of the parents on the use of the emotional communication of the infant, a between subject effect had been conducted for the use of emotional communications behavior and the demographics. In Table 6 the outcomes are shown for the effect of gender, prematurity, income and education level on the emotional communication behavior during the dyadic interaction.

Table 6

The influence of demographic factors on the emotional communication behavior used during dyadic interaction. Demographics factors n Degrees of freedom (df) F P-value Single behaviors Gaze Gender 28 1 3.083 0.91 Prematurity 28 1 .219 .643 Income Mother 27 1 .044 .836

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Income Father 24 1 1.055 .316

Education level Mother 28 1 2.052 .164

Education level Father 27 1 .373 .547

Positive facial expressions

Gender 28 1 .007 .932

Prematurity 28 1 .323 .574

Income Mother 27 1 .366 .551

Income Father 24 1 .341 .565

Education level Mother 28 1 .396 .535

Negative Facial Expressions

Gender 28 1 .628 .435

Prematurity 28 1 2.918 .100

Education level Father 27 1 1.562 .223

Vocalizations

Gender 28 1 8.785 .006*

Co-occurrence of emotional communication behavior Gaze & positive facial

expressions N (df) F P-value Gender 28 1 .018 .893 Prematurity 28 1 .031 .861 Income Mother 27 1 .189 .667 Income Father 24 1 .231 .635

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Gaze & negative facial expressions Gender 28 1 1.194 .285 Prematurity 28 1 .198 .021* Income Mother 27 1 .743 .397 Income Father 24 1 .330 .572

Education level Father 27 1 2.289 .143

Gaze, positive facial expressions & vocalizations

Gender 28 1 2.909 .100

Income Mother 27 1 1.270 .271

Education level Mother 28 1 4.777 .038*

Gaze, negative facial expressions & vocalizations

Gender 28 1 4.142 .052

Prematurity 28 1 6.535 .017*

* significant p <.05

The results of the demographics with the single and co-occurrence of the emotional communication behaviors during the dyadic interaction are shown in Table 6. For the single behaviors only, vocalizations and gender are significant. F (1) = 8.785, p = .006. Boys show more vocalizations then girls and both show more vocalizations towards the mother as shown in Figure 5.

For the co-occurrence of behaviors gaze and negative facial expressions and

prematurity is significant F (1) = .198, p = 02. The use of positive emotional communication (i.e., gaze, positive facial expressions and vocalizations) and education level of mother is significant F (1) = 4.777, p = .04. Infants of mothers with a scientific education show more

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positive emotional communication. The use of negative emotional communication (i.e., gaze, negative facial expressions and vocalizations) and prematurity is significant F (1) = 6.535, p = .02. The preterm infants show more gaze, negative facial expressions and vocalizations to mother compared with full-term infants.

Figure 5. Significant results of demographic factors in emotional communication of the infant.

Triadic interactions

In Table 7 the outcomes are shown for the effect of gender, prematurity, income and education level on the emotional communication behavior during the triadic interaction. Table 7

The influence of demographic factors on the emotional communication behavior used during triadic interaction. Demographics factors n Degrees of freedom (df) F P-value Single behaviors Gaze Gender 27 1 .730 .401 Prematurity 27 1 1.054 .314 Income Mother 26 1 .387 .540 Income Father 23 1 2.386 .136

Positive facial expressions

Gender 27 1 1.135 .297

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Education level Father 26 1 .377 .545 Negative Facial Expressions

Gender 27 1 .806 .378

Vocalizations

Gender 27 1 .937 .342

Income Mother 26 1 1.096 .306

Education level Father 26 1 5.846 .024*

Co-occurrence of emotional communication behavior

Gaze & positive facial expressions n (df) F P-value

Gender 27 1 .038 .846

Prematurity 27 1 1.037 .318

Income Mother 26 1 .839 .369

Income Father 23 1 1.356 .258

Education level Mother 27 1 .734 .400

Education level Father 26 1 .475 .497

Gaze & negative facial expressions

Gender 27 1 .260 .615

Gaze, positive facial expressions & vocalizations

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Gaze, negative facial expressions & vocalizations

Gender 27 1 .664 .423

* p <.05

The results of the demographics with the single and co-occurrence of emotional communication behaviors are shown in Table 7. As seen in Table 7 of the single behaviors, only vocalizations and education level Father is significant. F (1) = 5.846, p = .02. As shown in Figure 6 infants of fathers with a scientific education show less vocalizations. For the co-occurrence of behaviors, the positive emotional communication (i.e., gaze, positive facial expressions and vocalizations) and gender is significant during the triadic interaction F (1) = 5.040, p = .03. In Figure 6 it is visual that boys show more positive communication during the triadic interaction compared with girls.

Figure 6. Significant results of demographic factors in emotional communication of the infant.

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Discussion

Infants’ emotional communication has been demonstrated to be crucial for children’s later socio and emotional development. The current study investigated infants ‘ability to coordinate the three main emotional behaviors of emotional communication (i.e., gaze, facial expressions and vocalizations), exploring communicative patterns both with familiar social partners (i.e., mothers and fathers) and unfamiliar social partners (i.e., experimenter). In addition, the present study aimed at exploring whether there exist already at 4 months of age, differences in communicative patterns during dyadic (i.e., face-to-face) and triadic (i.e., with a toy) interactions. Furthermore, this study also explored the role of some demographics (i.e., gender, prematurity, income parents and education level parents) on the use of single

emotional communication behavior and the co-occurrence of this behavior. This exploration is important because gender, prematurity and SES is important for the development of infants (e.g., language development).

Emotional communication of the child towards the social partner during dyadic interactions

During the dyadic interaction infants show the most single behaviors of emotional communication towards the mother. These results are found in the literature and confirmed in this study. Besides the gazing and positive facial expressions towards the mother, they show more gaze and positive facial expressions towards the unfamiliar person than towards the father. In the research of Lin and Green (2009) the 4-month-old infants show more positive facial expressions towards the unfamiliar partner than towards the mother. The results of this study confirm that the infants show more towards the mother and unfamiliar than towards the father, although were not statistically significant. The negative facial expressions of the infant during the dyadic interaction and the vocalizations are shown the most often towards the familiar social partner (i.e., mother and father). This might come because the infants feel the most comfort by the familiar partner and that they know how to get the attention of the parent.

The patterns of correlation of the single emotional communication behavior shows that infants vocalize more when they also using more negative facial expressions, this also might come because they know how to get the attention of the parent. With the unfamiliar social partner, the infant uses more positive facial expressions. This might have something to do with familiarity.

The co-occurrence of negative facial expressions and vocalizations are significant. The infant shows more negative facial expressions while gazing towards the familiar social partner then towards the unfamiliar social partner. It is notable that they also do this with positive

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facial expressions while gazing unless this is not significant. What is significant is the co-occurrence of the behaviors of negative emotional communication (i.e., gaze, negative facial expressions and vocalizations) towards the familiar social partner compared with the

unfamiliar social partner. The infants show more positive emotional communication (i.e., gaze, positive facial expressions and vocalizations) towards the mother and experimenter and less towards the father. The study of Colonnesi et al. (2012) found in their study that infants vocalize more in combination with positive facial expressions to their mother compared with father so this result in this study is a confirmation that infants show more positive emotional communication towards the mother.

Emotional communication of the child towards the social partner during triadic interactions

Results suggested differences on the infants’ communicative behaviors when comparing dyadic and triadic interactions. It is remarkable that the infants gaze longer towards the unfamiliar social partner and show more positive facial expressions than towards the familiar social partner compared to the dyadic interaction. In the results of the co-occurrence of the behavior it is also visual that the infants show more positive facial expressions while gazing towards the unfamiliar social partner compared to the familiar social partner. That 4-month-old infant’s gaze longer to the unfamiliar social partner compared to the familiar social partner is not a novel finding, Lin and Green (2009) found the same in their research but this was during the dyadic interaction. The expectation was that because of the research of Striano and Stahl (2005) we expected that when the infants show more gaze and positive facial expressions towards the mother during the dyadic interaction, it would be the same during the triadic interaction. Aureli et al. (2017) wrote in their research that the symmetrical interaction between mother and infant during triadic interaction are mutually engaged and that why it was expected that infants gaze longer to mother and smile longer to mother. Infants vocalize more to mothers during the triadic interaction. Notable is that, unless not significant, the infants show the most negative facial expressions towards the father compared to mother and experimenter. For the positive emotional communication, positive facial expressions and vocalizations while gazing during the triadic interaction the infants show this the most often towards the familiar social partner.

The same as in the dyadic interaction, the infant show more negative facial

expressions while gazing towards the familiar social partner compared to the unfamiliar social partners. They show more negative facial expressions towards the father during the triadic interaction than towards the mother compared with the dyadic interaction. The same was also

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found for the negative emotional communication, namely infants show more negative facial expressions and vocalizations while gazing towards the familiar social partners than the unfamiliar social one.

Emotional communication of the infant towards the social partner and the effect of demographic factors

The dependent factor gender in the emotional communication is a factor that might influences the emotional communication of the infant. During the dyadic interaction the difference between boys and girls for gaze is almost significant. This might be significant if there is a larger sample. For vocalizations it is significant and boys vocalize significantly more towards the social partner then girls during the dyadic interaction. Gender is also significant for the positive emotional communication of the infant during the triadic interaction. This study implicates that there are gender differences in the use of emotional communication towards the social partner. The hypothesis that girls show more emotional communication towards the social partners compared to boys is not accepted because boys show more positive emotional communication towards the familiar and unfamiliar social partner.

Prematurity is also a factor that is significant. It is significant for the negative facial expressions while gazing and the use of negative emotional communication in the interaction with the familiar and unfamiliar social partner. Out of the literature we know that preterm infants are show more negative affect towards the social partner (De Groote et al., 2006; De Schuymer et al., 2011).

The influenced of the social economic status of families on the social communicative development of children is well written. Out of this study comes that during the dyadic interaction between infants and their social partners during the positive emotional

communication the education level of mother is significant. Out of this sample it looks like the children show more emotional communication when the mother has a scientific education. The education level father is significant for the use of vocalizations during the triadic

interaction. In this sample the result is that children vocalize more when the father has a lower education than a scientific education. Out of this literature it is clear that the verbal interaction between parents and children from families with a low-SES is less rich (Brockmeyer et al., 2012).

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Limitations

A limitation with respect to the analysis should be noted. The first limitation is the sample size. Out of the performed G*power a sample of 51 participants was necessary. For the purpose of the study the analyses are done, but it is preferable to repeat this study with a larger sample to investigate whether a number of components that show a trend now may be significant.

In the sample of 34 there were 3 preterm infants. It would be good to test this hypothesis with a larger sample to investigate the emotional communication of preterm infants instead of the synchrony of the communication of preterm infants compared to full-term infants like De Schuymer et al. (2011) has done.

In this sample the SES is above average. Because of the SES of this sample is high it is not a good representation of the population and therefore this research cannot be

generalized. It would be interesting because of literature about the consequence for the language development of infants in a low SES family to test this in a sample that consist of a group of infants with low SES and a group of infants with high SES. This can give

implications for the clinical practice and the way clinical can support the infants and family with low SES.

Conclusion

The present study confirms previous research results about the use of emotional

communication of 4-month-old infants. This research did also some exploratory about some demographic factors which might influence the use of emotional communication of 4-month-old infants. Emotional communication in the dyadic and triadic interaction is imported for the social communicative development of infants because the use of emotional communication is important for the language development and understanding of meanings and intentions of others. The intention of others is important for the development of Theory of Mind.

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