I

ON THE DEVELOPMENT OF THE CHILD'S ABILITY TO IDENTIFY AFFECTIVE STATE FROM THE PROSODIC FEATURES OF ADULT SPEECH

Piroska Klintbjer Åsa Nilsonne Greta Ågren

Linköping University Departrnent of Conununication Studies SIC 9, 1984 LiU-Terna K-RB-84-9 ISSN 0280- 5634 ISBN 91 - 7372- 86 1- 6

Address : Departrnen t of Conununication Studies Linköping University S-581 83 LINKÖPING Sweden

Tel: 013-28 10 00

Vid filosofiska fakulteten vid Linköpings universitet bedrivs forskning och ges forskarutbildning med utaångspunkt från breda problemområden - teman - i stället för traditionella akademiska discipliner. Det finns fyra teman: Hälso- och sjukvården i samhället, Kommunikation, Teknik och social förändring samt Vat­ten i natur och samhälle. Forskningen inom varje tema sker i samverkan mellan forskare med olika vetenskaplig balegrund. Verksamheten startade 1980 och efter en uppbyggnadspcriod om 6-7 år kommer varje tema att ha 20-25 fasta for­skartjänster - professorer, docenter etc - och cirka 40 forskarstuderande.

Tidigar e utgivna rapporter:

SIC 1 Linell , P.er. Modeller och metafor e·r för kommunika ­tion. 1982 .

SIC 2

SIC 3

SIC 4

SIC 5

SIC 6

SIC 7

SIC 8

SIC 9

Linell , Per .The ~ritten Zanguage Bias ~n Linguistics. 1982.

Svensson , Cai Om_ Kqmmun ikation , 1 . Ett urva l för e drag från tema - K: s sympos ium den 25 - 26 maj 198 2 . · 1982 . ·

Gustavsson, L & Hult , H {utg}

Te xt och bild i Z~romedel ;· Sju ana ­lyse r av svenska som . andrr:is pråk . 1983 .

Severinson Eklundh, ~erstin The Not~on ·of Language Game -A Natural Unit ~f Dialogu~ and Discours e . 1 983.

Granström, Kjell (red ) Om Kommunikati on , 2 .. Ett urval för e drag från tema-K : s sym­pos ium den 26 - 27 maj 1983 . 1983 .

Hansson , Gunnar (red)

Nordenfe l t, Lennart

Litteratur som korrnnmunikation : Förståelser , tolkningar, värderingar . 1983 .

Five studies in action theory . '1984 .

Klintbjer , Piroska On the development of the child ' s ab1'. l7'.ty to identify affec tive s tat e from the prosodic f eat­

,~~-rrr / li,y ur es of adult speech ~r.v4 1..1 'f-0~ ~ ~ ~~~C)

~1; ·~-.; f Oj, «.,4

'11\/c ut-i' ..J

ISSN 0280 - 563 4

III

CONTENTS

Introduction

2 Material and methods 3

3 Results 5

3. 1 Sex diff erences 5

3.2 Ontogeny 5

3. 2.1 "Anger" 8

3.2.2 "Sur prise'' 8

3.2.3 "Sadness" 8

3.2.4 "Happiness" 9

3.3 Judgements of the male and f emale voice 9

3.4 Judgements of the diff erent emotions 13

3.5 Misjudgements 13

4 Discussion 1 5

5 Ref erences 20

IV

Addresses :

Pir oska Klintbjer

Department of Communication Studies University of Linköping

Åsa Nilsonne

Karolinska Institute

Department of Psychiatry

S:t Görans Hospital

Stockholm

Greta Ågren

Department of Zoology

University of Stockholm

Abstract

The ability to judge emotional states (anger, surprise, sadness and

happiness) from the non- verbal components of speech was studied in

169 children aged from 4 to 10 years (20- 43 children per group, one

gr oup for each year of age except 9) in Uppsala, Sweden . 19 adults

were used as a control group. The stimulus material consisted of

speech samples, in which a male and a female actor had been in­

structed to portray the indicated emotional states .

In general, the ability to make correct judgements increased with

increased age. This was especially the case with the recognition of

"surprise", "sadness" and "happiness", for which emotions increasing

improvements were seen up to t he age of 8, where the ability was

close to that of the adult controls. The abi l ity to recognise an

angry voice appeared to be well developed already at the age of 4. The most difficult item was the male voi ce portraying "happiness",

where the children did not show and increase in their scores until

the age of 8 . Gi rls were found to have a more developed abilit y to

identify the expressed emotions in all age groups .

In most cases where erroneous judgements were made, the male voice

was judged to be angry and the female to be sad, irrespective of

intended emotion and of the sex of the child.

Introduction

Human communication can be divided into verbal and non- verbal com­

ponents. The verbal component is expressed in words and sentences.

Non- verbal vocal communication consists of the prosodic features of

speech and vocal expressions as laughter, giggles, screams, sobbing

etc. Non- verbal communication also includes body language , touch and

chemical signals.

In the study of prosody the stress is on how something is said rath­

er than on what is being said, i.e. the information that can be

transmitted through the intonation, pitch, amplitude and pauses of a

speech sample.

The laryngeal muscles are under voluntary control which enables a

speaker to modify his or her voice as for instance ac t ors do. On the

other hand, under conditions of emotional arousal, there is also a

non-voluntary influence on the voice mediated by changes in the

breathing pattern and in the action of the laryngeal muscl es. It has

been suggested that the limbic system of the brain is involved i n

these processes (Scherer 1979).

The fundamental frequency of the voice (pitch) is determined by the

interaction between the laryngeal and breathing muscles . Several

reports have shown that the fundamental frequency contour varies

with the emotional state of the speaker. For instance, speech tempo

is high in an angry or frightened voice, but slow in a sad voice.

Anger is loud, sorrow is quiet (Williams & Stevens 1972 , Kotlyar & Mo rozov 1976, Scherer & Oshinsky 1977).

The prosodic qualities of speech can thus mediate information about

emotional state. When studying this type of human communication, the

prosody must be isolated from the verbal content of the utterance .

Many different methods have been developed to this end.

Test stimuli without linguistic content as for instance t he alphabet

have been used (Dusenbury & Knower 1939, Davitz & Davitz 1959) ;

2

alternatively test sentences without emotional content - neutral

sentences - have been presented in different emotional modes

(Dimitrovsky 1964, Fenster & Goldstein 1971) . The ver bal content can

be masked by presenting only the fundamental frequency (Göranson et

al. 1981) or by using randomized splicing (Scherer 1971, Scherer et

al. 1972) . Synthetic stimuli - electronically generated tones - can

be varied in a controlled way and have also been used in this kind

of investigations (Scherer et al. 1977).

Prosody is the dimension of language which is first discovered and

understood by children (Wood 1976).

Wood (1976) proposes five developmental stages in the child's under­

standing of prosody.

Stage 1 (4 months)

Stage 2 (18 months)

Stage 3 (2 1/2 yrs)

Stage 4 (5- 12 yrs)

Rough recognition of the prosody in a happy

vs. unhappy voice .

Children exaggerate the intonation when they

begi n to speak in order to make themselves

understood.

The prosody becomes complementary to the

linguistic context of the child's speech.

The child lear ns to identify a wider range

emotions with increasing reliability. Verbal

and non-verbal information can be understood

separately.

Stage 5 (after 12 yrs) The child learns to understand conflicting

messages, i . e. when the prosody does not

carry the same informati on as the verbal

content of the utterance.

The aim of this study was to study the ontogeny (Stage 4 according

to Wood) of the child's ability to identi fy different emotional

states in the speaker from prosodic information alone.

3

The specific Questions investigated were:

Are there sex differences in this ability?

How developed is this ability at different ages?

Is thc rnale and the female voice perceived in the same way?

Does identification of the different emotions present

different degrees of difficulty?

2 Material and methods

A test tape (kindly provided by Anne- Marie Öster, Royal School of

Technology, Stockholm) containing recordings of a male and female

actor reading six neutral sentences in four different emotional

modes was used. The emotions were: anger, surprise, sadness and hap­

piness. The sentences were: A. "Fröken kom för sent till skolan"

(The teacher was late for school), B. "Bollen studsade in genom

fönstret", (The ball bounced in through the window), C. "Det var

Olle som vann tävlingen", (It was Olle who won the competition), D. "Sommarlovet börjar sent i år", (Summer vacation begins late this

year), E. "De kommer på torsdag", ( They will arri ve on Thursday),

and F . "Det finns en råtta i skafferiet", (There is a rat in the

larder). The tape was played to children and adult controls who were

asked to try to identify the emotional state of the speaker. Fach

emotion was presented four times, the test thus consisted of 16

stimuli .

The children and the adult controls were provided with answer forms. For each sentence there were four possible answers of which only one

was correct. The sentences were played with intervals of 10 seconds

and the test lasted for approximately 10 minutes. The children were

aged between 4 and 10 years (see table 1), they were recruited from

11 different groups of children at day care centers, pre- school and

primary school .

Table 1.

Sex

Female

Male

4

Age distribution of the children

4 5

15 9

15 15

30 24

Age (years)

6

10

10

20

7

11

11

22

8

20

23

43

1 O* Adul t

?

?

20

8

11

19

73

86

178

* Data of sex distribution not available (data kindly provided by A- M Öster . )

The 4- 7 year old children were tested individually and they gave

their answers orally . The 8 and 10- year olds and the adult controls

were tested in groups and gave their answers on the forms provided

for them. The test session started with an oral instruction by the test leader, the instructions were the same for every individual or

group. The children were shown schematic pictures of faces portray­

ing the emotions in question in order to make sure that they could

recognize and name the investigated emotions. After this there was a short discussion about different means of expressing emotions. Four practice sentences were played and evaluated together with the test

leader . Finall y the test subjects were asked whether they had any

questions regarding the test procedure . When eventual questions had been answered the test was administered as described .

In the statistical analysis the x2- test, Fisher's exact probability test and the sign test were used .

5

3 Results

69% of the total amount of ratings were correct . The distribution of correct and incorrect answers in relationship to sex and age is

shown in figs . 1-4 (see last page).

3.1 Sex differences

A comparison between the results obtained by the sexes within each

age group shows that the girls have an overall better score than the

boys (P<0 . 01) (table 2).

Table 2.

Sex

Female

Male

Percentage correct answer s within each age group in relationship to sex.

4

51

47

5

55

59

Age (years)

6

76

69

7

73

73

8

92

82

71

67

Adults

99

93

The distribution of correct answers for gir ls and boys respectively regar ding the different emotional states as presented by the male

and the female voice is shown in fig 5 . After the age of 7 the girls

have better scores than the boys as regards most emot i onal states . This difference persists in the adult contr ol group. The material is

not large enough to permit the difference to be proved statisti­

cally.

3.2 Ontogeny

The children achieve better scores the older they are (table 2) . The

di fference bet ween 4- and 5- year old girls is significant (P<0 . 01), the same applies to the differences between 5- and 6-year olds

(P<0.01) , no difference is found, however, between the results of

6

MALE VOICE O/o ANGER O/o HAPPINESS 100

--f:f- -~ 100

o_ _ ... - • .-....... ;;;> • 80 0 80

0

60 60 • / /

/ /

40 40 0 / /

e/'.'.'. • 20 20

/

/ / 0

0 / /

Il > ,, / dl • I >

' 4 5 6 7 8 years /4 5 6 7 8 years

Fema l es; r =0 . 95 , df=4' p <0 .01 Fema les; r =O .80, df=4. NS Ma les • r=0.89, df=4, p <0 .05 Males • r=0.30, df=4, NS

FEMALE VOICE O/o ANGER O/o HAPPINESS 100 0 • 100 ---- o ....... - ./

.......... .......... ......

80 80 ........ .» .......... o...,..... ........

0 .......... ........ 60 • 60 -6

..........

40 40

20 20

ll I> I I I > I '4 4 5 6 7 8 years 5 6 7 8 years Females; r =0 .55, df=4, NS Females; r=0.94, df=4 ' p <0 . 01 Males r=0.43, df=4, NS Males

' r=0.95, df=4' p <0 . 01

Fig. 5. Percentage correct judgements relat ive to the age of the mal e ( 1 ---and the fema l e ( o ) subjects for the male and the female vo ice, and the four emotions .

0/o SURPRISE 100

80

60

40

20

5

/

/ /

0 ~ Q 0

•

6 7

Femal es; r=0 .95, df=4 , P <0.01 Males ; r=0 . 89 , df=4 , P <0. 05

O/o SURPRISE 100

80 /

/ ./ 0

60 ./ ./

/ . / 0 ./

./ 40 ./

/ /

0

20

I 4 5 6 7 "

Fema les; r=0 .83, df=4, P <0.05 Males ; r=0.95 , df=4, P <0. 01

7

MALE VOICE

0

' /

'> 8 years

0/o SAONESS 100

80

60

40 °

20 0

5 6 7 Fema l es; r=0 . 50, df =4, NS Ma les ; r=0 . 98 , df=4 , P <0.0 1

FEMALE VOICE

0

'> 8 years

O/o SADNESS 100

• <It :?"

-?' 80

/ /

/ /

60 / /

9-/ 0

40 •

20

I

4 s 6 7

Femal es; r=0.96 , df=4, P <0. 01 Ma l es ; r=0 . 88 , df=4, P <0.05

0

'> 8 years

'> 8 years

8

the 6- and 7- year old girls. The 8 -year old girls again have sig­

nifi cantly bett er scores than the 7- year olds girls (P<0.01 ). A

final improvement of the results can be seen between the 8 - year old

girls and adult women (P <0.025) .

Among the boys there is no difference between the results of the 4-

and the 5-year ol ds . Between the ages of 5 and 6, however , ther e is

an increase i n the number of correct ratings (P<0.05) . Between 6-and 7- year old boys there is no measureable improvement which cor­

responds to the findings among the girls. The 8- year old boys again

improve as compared to the 7- years ol ds (P<0. 05). Finally the adult

men had a greater amount of correct ratings than the 8- year old boys

( P< O. 01 ) .

As the differences between the sexes were smal l , the results from

boys and girls have been pooled within each age group to allow

further statistical evaluation.

3 . 2 . 1 "Anger"

The "angry" voice of the male, as well as the female voice was

recognizable al ready t o the 4-year olds (P<0 . 01) . An i mprovement of

the ratings was seen at t he age of 7 (P<0.05) . No further develop­ment after that age was seen (fig 6) .

3.2 . 2 11 Surprise"

The 4- year olds could also recognize both t he male and t he female

rendition of 11sur prise" (P<0.05) . This ability did not improve until

the age of 6 (P<0 . 001). There was no significant difference between

the 6 and 7-year olds, but there was an improvement between the ages of 7 and 8 (P<0.025) . No fur ther improvement was noted (fig 6).

"Sadness"

In the case of the male voice , it was not until the age of 8 that

the children were able to identify sadness correctly

(P<0 . 01) (fig 6) .

9

The development then parallels that of "surprise" . An improvement

between the ages of 4 and 6 (P<0 . 05) but no difference between the 6- and 7- year old boys was found. Between the ages of 7 and 8 there was again an amelioration of the results (P<0.05)(fig 6) .

The f emale voice was correctly assessed already by the 4- year olds (P<0. 001). There was a significant increase in correct answers at the age of 5 (P<0 . 001 ). Another increase was seen between the ages

of 7 and 8 (P<0.01)(fig 6) .

"Happiness"

The ability to identify the mal e voice portraying happiness was not demonstrated until the age of 8 (P<0.001) . The female voi ce was cor­rectly assessed already by the 4-year olds (P<0.001). The develop­

ment of the ability to correctly assess the female voice again

showed the same pattern as the ability to judge the surprised voice ,

that is there was a difference between the results of t he 4- and 6-year olds (P< 0.001 ) . There was not reliable difference between the 6- and 7- year olds but between the 7- and 8- year olds there was

another improvement (P<0 . 01) (fig 6).

3. 3 Judgement of the male and femal e voice

66% of the judgements of the male voice were correct as cornpared to

71% of the judgements of the female voice. This constitutes a sig­nificant difference (P<0. 05) . Table 3 shows the results for the var ious age groups as regards t heir ability t o correctly recognize

the emotional content of the male and female voice respectively .

10

O/o ANGER 100

_____......----. ' 0 0 0 0 0 0 0 ' 0 ','•Mo•.'.'~ .. .. .. ·

80

60

40

20

~'-'~--~----~--~~~--~~~--/~,~~----~~~....,._~ r 4 5 6 7 8 10 years ' / ~ Adults

O/o SURPRISE 100

80

60

40

20

I > I I I I I ,~....____.~_._~_._~_._~~--~~~~-r1

4 5 6 7 8 10 years Adults

Fi g. 6 Percentage correct judgements of t he ma l e (• -------- ) and the fema l e (6 -------- ) vo i ce per age group and emotion.

O/o

100

80

60

40

20

SADNESS

I I

I ~

/

f /{

1 1

--6----- ··· ·· ···· ·· ···6 .L:s- --_,, .... ... .... p" .... .. .. ~

/

I I /1 > '1-4.____.5.____.6 _ _.7_ ..... 8 __ ___..10--y-ea_r_s~' />---A-d ...... ul-ts-~

0/o HAPPINESS 100

80

60

40

20

~ å-"

~ I

/ ~

IS /

/

A----······ ··· ··· ·····6

~--........... ··· ····· ·

I I /1 > ',_4"'---5'--__.6.____7.___8.__ _ _.....10--ye-a-rs _ __,, ,r---A-d-'-u-l ts-~

Table 3 .

Sex

Age (years)

Male voice

Fem ale voice

p

Sex

Age (years)

Mal e voice

Female voice

p

12

Percentage of corr ect answers regarding the male respectively female voice per sex and age group.

Female

4 5 6 7 8 Adults

34 52 78 62 90 98

53 57 74 82 93 100

< o. 001 < 0 . 05 < 0 . 01

Male

4 5 6 7 8 Adults

35 39 66 62 83 94

45 62 72 81 82 95

< 0.001

From table 3 it can be seen that the female voice is more often cor­rectly identified than the male voice throughout the age groups . In

the cases where the differ ences are significant the P- values are entered into the table .

In a comparison between the ability of the boys and that of the

girls to judge the male and the female voice , no difference could be found except in the case of the 8- year olds judging the female voice where the girls had 93% right answers which is significantly better than that of the boys who had 82% correct answers (P<0 . 001 ).

1 3

3.4 Judgements of the different emotions

The "angry" voice was the easiest to identify (table 4), and "anger"

in the male voice was more readily identified than in the f emale

voice (P<0.01). The female voice portraying "sadness" and "happi­

ness" were the next two most easily identified stimuli.The differen­

ces in judgements of the male and female "surprised" voice were not

significant.

Table 4 Percentage correct answers r egarding the male and female voice in relation to the expressed emotions .

Expressed emotion "Anger"

Male voice 88

Female voice 80

p < o. 01

"Surprise" "Sadness"

61 43

62 77

< 0 . 01

"Happiness"

33

68

< 0.01

The most difficult voices to identify were the male voice portraying

'1 sadness" and "happiness". The "happy" male voice was correctly

identified less frequently than any of the other st imuli (P <0.001) .

3.5 Misjudgements

On the whole the girls and the boys chose the same alternatives when

making incorrect judgements (figs 1-4). The boys aged 4-7 chose 11 anger 11 as the main incorrect alternative to all the expressed emo­

tions of the male voice (P<0.05). The girls have made similar

assessments, except in the case of "sadness" as expressed by the

male voice where "surprise" was the main wrong choice (P<0 .05) .

The female voice was in most cases judged to be expressing "sadness"

when a misjudgement was made. This applies to children of both sexes

up to the age of 7.

Fo 1 Hzl

200

100

0 1 2 time Is)

A. SURPRISE. HALE VOICE .

Fo !Hz)

200 ~

100

0 1 2 time ( s)

B. ANGER . FEHALE VOICE.

Fo !Hzl

400

200

0 1 2 3 t i me ( s)

C. SURPRISE. FEHALE VOICE.

F0 <Hzl

200

100 \ t :;::...

0 1 2 t ime ( s)

0 . SURPRISE . MALE VOICE .

14 Fo (Hz)

200

~ 100

0 1 2 time (s)

A. ANGER. MALE VOICE.

Fo !Hz)

200 V\!'!\ 100

't~_._~~~--~~~ ............. ~---> 0 1 2 time (s)

B. HAPPINESS. MALE VOICE.

F0 !Hzl

200

100

r. 0 1 2 3time(s)

C. SADNESS. FEMALE VOICE.

Fo (Hz)

200

J~ vJ 100 \

c :;::... 0 1 2 3 4 t ime (s)

D. SADNE SS. MALE VOICE.

Fig . 7. Fundamenta l frequencies (F0) of some of the test sentences (A to D, see methods) .

15

After the age of 7 there was no clear pattern in the choice of in­

correct alternatives.

The fundamental frequency (fig 7) of the various test sentences has

been extracted in order to see if there were similarities between

the stimuli that were confused. The male voice, unlike the female one, did not show a lesser variation of fundamental frequency in the "sad" recordings . This could have made identification difficult, es­

pecially since the fundamental frequency contour was not much dif­ferent from "surprise" and "anger" resp., although t he mean funda­mental frequency was lower.

4 Discussi on

The results of the present study were mostly in agreement with pre­

vious work. Firstly, the results of this investigation suggest that

girls are more successful in perceiving the non- verbal emotional content of a spaken utterance than boys are . In studies where a

larger number of persons were tested (Dimitrovsky 1964: N=225,

Rosenthal et al. 1978: N=2615) this sex difference was more pro­nounced. However, in a pilot study of 163 persons Scherer & Oshinsky

(1977) did not find any difference between the sexes.

Secondly, the children improved in their ability to correctly assess the emotional state of the speaker from year t o year up to the age

of 8 at which age their scores did not differ from those of the adult control group. These results are also in agreement with previ­

ous findings (Dimitrovsky 1964, Fenster et al 1971, Scherer & Oshinsky 1977 , Rosenthal et al . 1978).

Thirdly, it was found that "anger" seemed to be more easily recog­

nized than "happiness", findings that coincide with those of Dimitrovsky (1964), Kotlyar et al. (1976) and Rosenthal et al.

(1978) . Scherer & Oshinsky (1977), on the other hand, finds "happi­ness" to be more easily recognizable than "anger" in a pilot study .

1 6

Fourthly, when the children made misjudgements in this study,

"anger" and "sadness" were the most frequently chosen alternatives.

This is in agreement with Dimistrovsky's (1964) finding that, when

mistakes were made, positive emotions were judged to be negative .

Finally, the results of this study suggest that the female adult

voice was in general easier to interpret than the male voice, in

particular when expressing "sadness" and "happiness". The male voice

communicated "anger" more successfully. This feature has not pre­

viously been reported. However, in this study the test sentences

were read by only one person of each sex. Thus, it cannot be estab­

lished whether the above-mentioned difference was due to sex diff­

erences in general or ind ividual differences between the actors.This

aspect needs further investigation. A further methodological diffi­

cul ty was that the emotional content of the sentences was simu­

lated. Possibly there is a difference in the acted and spontaneous

expression of emotion. However, the present test sentences were

interpreted by professional actors, trained to simulate emotions.

Furthermore, the females in the adult control group gave correct

answers to 99% of the stimuli, and adult men and girls of 8 years of

age gave correct answers to more than 90%. Thus, the actors ex­

pressed the sentences in a way that was easily interpreted by

adults. A related difficulty stems from the verbal content of the

sentences whi ch the children may not have been able to disregard.

Thus, some sentences may not have appeared neutral to them. (E . g.

there's a rat in the larder) -

Investigators of prosody rarely discuss their results f rom a bio­

logical point of view. However, the physiological background of the

gradually improving ability to assess the prosodic qualities of an

utterance has received attention in studies of neural development

(Wood 1976). The finding of several investigators, that girls begin

to talk earlier than boys do, and that they achieve better results

in tests of verbal skills such as spelling, language acquisition and

vocabulary has also been discussed in this context (e.g . Freedman

1979). Thus, Freedman (op. cit.) relates these sex differences to

differences in dominance between the two brain hemispheres . The left

17

hemisphere reportedly controls verbal tasks, while the right one

controls spatial tasks (Bogen 1969, Bower 1970, Dennis & Whitaker 1976) . Kimura et al. (1967) showed that the left hemisphere becomes dominant as regards speech 2 years earlier in girls than in boys.

The present findings can also be discussed in terms of a more gen­eral biological perspective: especially in social species, that is

in species where individuals live in groups, the communication of

emotional state enables the different individuals to interact with one another in an adequate way . The ability to encode and decode

emotional information can thus be discussed from the point of view of function against the background of the evolutionary past of human

communication. There is a disagreement about many aspects of early

man and his predecessors, but hardly about his social nature. Thus

it seems likely that man had a well- functioning system for communi­cation of i mportant emotional states bef ore the development of sym­

bolic language. Language in this highly developed form is considered

to have become possible with the development of the neocortex; the

older system for vocal, non- verbal communication underlies and colours speech production - especially in emotional situations

(Chevalier-Skolnikoff 1973).

Prosodic features of speech can thus be seen as expressions of this

primitive system - this can be illustrated by the communicative pro­

perties of the infants' cries . The crying becomes differentiated at

an early age allowing mothers to identify hunger, fear and discom­fort. Tankova- Yampolskaya (1968) analyzed the intonation curves of the newborn infant's cry and adult vocalizations in different emo­

tional states. She found that the intonation patterns when expres­

sing discomfort were identical. This is probably an effect of the "buil t in" vocal communicati ve system as proposed by Darwin already in 1872. However, the proficiency of the individual develops with

age through interactions with other individuals, which allows lear­

ning of the more complex and culturally determined forms of signal­ling emotion, and through neuronal interaction (cf. above).

18

For example, in social mammals, including primates such as man, so­

cial signals are involved in the establishment of dominant rank

orders which are of intrinsic importance to many aspects of social life, e .g . in the distribution of food.

Relevant to the present investigation are the results of several studies of children born blind in different cultures. These studies support the concept of an ability to express and interpret aggres­

siveness which is in evidence early in life and which does not seem

to reQuire learning. Our finding of a well developed ability to per­ceive anger even in the youngest group of children (4 years old) is

in accord with this concept. Eibl-Eibesfeldt (1976) also describes

how small children compete for the mother's breast, for food and toys, and how they try to establish a rank order. Similarly, Palluk

and Esser (1971) report that children defend their rank already at one to one and a half years of age.

The function of a rank order as a means of reducing the amount of o­vert aggression depends on the ability to recognize the threat sig­nals . In this context the observed well- developed ability of the

small child to recognize anger makes sense. Accordingly, misinter­pretation of "happiness" should involve lower risks than any mis­interpretation of "anger". Hence , in case of uncertainty, an inter­pretation of "anger" would be the safest alternative, which also

corresponds with the experimental results from this and other i nves­tigations .

However, the "angry" and the "happy" voice show many similarities as

to freQuency, pitch, volume and tempo (Scherer & Oshinsky, 1977). It

may therefore be difficult to judge whether a voice is "happy" or "angry" from intonation only. In this context Van Hooff's (1972) hypothesis concerning the phylogenetic development of laughter from

threat through signals of submission is interesting, If this is true, the ability to show threat is the more primitive system.

Considering the importance of being able to encode and decode threat

signals correctly, it is likely that the different non- verbal chan-

1 9

nels for signalling emotion - that is prosody, facial expression,

post ure etc . should, each by i tself, be suffi cient to allow recogni­

tion of the threat. If the "happiness" signal did develop from a threat the differences must be large enough to avoid confusion. Pos­

si bly, for this reason and the relative recency of this type of sig­

nal (van Hooff, op.cit.), the communication of "happiness" may re­quire reinforcement via addit i onal communicative channels. This ex­plain why the children in this and other studies found it difficult

to identify the emotion "happiness" on the basis of the voice alone,

in particular in the male voice. However, not only "happiness", but also "sadness" in the male voice was more difficult to recognize

than in the female voice. These sex differences could possibly be

attributed to the cultural bias against expressions of sadness in males which could influence both the children and the male actor .

Thus some sex differences were found in communicative skills. These

differences can be discussed in terms of the social organization of

man . A social organization similar to that of e.g. hamadryas or gelada baboons and chi mpanzees has been considered to be relevant for early hominids. This is characterized by male aggressive domi­

nance and longterm maternal care (Jolly 1972, Wilson 1975).

The longterm close proximity between the juvenile and its mother to ensure its protection and nourishment also means, that the mother

will be of crucial importance in the socialization process . This

also applies to modern men . In this situation a superior communicat­ive ability in females should be of value . The males may achieve their goals by efficiently signalling and perceiving anger which is

in accord with our finding that the male voice was more efficient than the female voice in encoding "anger".

20

5 Ref erences

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Palluk, R.J. & Esser, A.H. (1971) . Controlled experimental modifica­tion of aggressive behavior in territories of severely retarded boys, Amer ican Journal of Mental Deficiency, 76, 23-29 .

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CORRECT ANSWERS

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INCORRECT ANSWERS

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Fig 4. Happiness. Distribution of the answers among the alternative emotions anger (An), surpi se (Su), sadness (Sa) and happiness (Ha), when happiness was expressed . In each pa i r of bars the left bar represents the answers of the female subjects and the r i ght one the answers of the male subjects .

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CORRECT ANSWERS

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Fig. 1. Anger. Di stributi on of answers among the alternative emotions anger (An), surprise (Su), sadness (Sa) and ha ppiness (Ha), when angerwas expressed . In each pair of bars the left bar represents the answers of the female subjects and the right one the answers of the male subjects.

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Fig. 2. Surpri se . Distribution fo answers among t he alternative emot i ons anger (An) , surprise (Su), sadness (Sa) and happines s (Ha), when surpri se was expressed. In each pair of bars the left bar represents the answers of the female subjects and t he r ight one the answer s of the ma le subjects.

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Fi g. 3. Sadness. Distribut ion of answers among the al ternative emotions anger(An), surprise (Su), sadness (Sa) and happiness (Ha), when sadness was expressed . In each pair of bars t he left bar represents the answers of the female subjects and the right ones the answers of the male subjects .