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Perceptions of cries of full-term and preterm infants
INFANT BEHAVIORAND DEVELOPMENT 5, 161-173 (1982)
Perceptions of Cries of Full-term and Preterm Infants* SARAH L. FRIEDMAN, CAROLYN ZAHN-WAXLER, AND MARIAN RADKE-YARROW
National Institute o f Mental Health Bethesda. MD 20205 Sixty-one mothers rated 12 infant cries. There were four cries (30 sac each) of healthy full-term neonates, four cires of very low-risk preterm infants, and four tires of medium-risk preterm infants. The cries were each rated on five 7-point scales with the conceptually "negative" polarity representing the urgent, grating, sick, arousing, and immature qualities of cries. Preterm tires were not uniformly rated as more urgent, grating, sick, arousing or immature than cries of full-term infants of the same conceptional age and of similar racial and socioeconomic background. Some preterm cries were rated as significantly more urgent, grating, sick, arousing or immature than full-term cries; other preterm cires were rated as significantly less urgent, etc., than full-term cries. Even though all the preterm infants were ostensibly healthy when their cries were recorded at expected date of birth, the ratings of the cries were related to the medical risk associated with the cryers' neonatal medical condition. The findings have implications for future research regarding cry features as adaptive ancl maladaptive communications that influence infants' development.
Mothers of preterm and full-term infants do not interact with their infants in the same way (Goldberg, 1978; Field, Goldberg, Stem, & Sostek, 1980). The interaction between preterm infants and their caregivers is believed to be less optimal than the interaction of full-term infants with their mothers. The less than optimal interaction in the preterms-mothers dyads is often attributed to the disruption of the bonding or attachment process due to separation between preterms and their mothers while the infants are in the hospital for intensive care (Barnett, Leidermann, Grobstein, & Klaus, 1970). It is reasonable to assume, however, that another contributor to caregivers' social interaction with preterms is the behavior of the preterms themselves. Infants' and children's behaviors are k n o w n to influence the behaviors of their caregivers toward them (Lewis & Rosenblum, 1974; Bell, 1979). A n example of infant behavior which is frequent and affects caregivers is crying (Bowlby, 1969; David & Appell, 1961; Erode, Gaensbauer, & Harmon, * Manyindividualshelped to makethis studypossible. MiltonWerthmann,of the WashingtonHospitalCentergave us accessto a populationof full-termand preterminfants.Mrs. AnneMayfieldrecruitedthe infants,Mrs. Blanche Jacobsassistedwiththe recordingof the cries. Mrs.GeriCoopermanand Mrs. JeanDarbyWelshrecruitedthe mothers who rated the cries and explainedthe procedures to them. Miss ChristineDavenportceded the data. John Bartko monitoredour choiceof statisticalmethodsand Mrs. JeanDarbyWelshwas involvedwiththe analysisof the data. Mrs. Eunice Keanellyand Mrs. Bertha LeCompte typed the manuscript.We thank these individualsfor their valuable contributionsand dedicatedinvolvementin the study.Correspondenceand requestsfor reprintsshouldbe addressedto: Sarah L. Friedman,NationalInstituteof Education, 1200 19 Street,N.W. Washington,DC 20208. 161
162
FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
1976; Murray, 1979). Crying provides a means of communication about the infant's needs. It is, simultaneously, an expression of affect that can impinge positively or negatively upon the caregiver. It can elicit the caregiver's comforting responses (Zeskind, 1980), and through the caregiver's responding to it, the attachment bond between infant and caregiver can grow. Consequently, if an infant's cries are for some reason unusual, they may have an impact on the quality of the interaction between the infant and the caregiver. It also follows that if preterms' cries are preceived as more negative sounding than cries of full-term infants, caregivers may respond to preterms differently from the way they respond to full-term infants. There is evidence to show that infant cries can be perceived as aversive stimuli (Frodi, Lamb, Leavitt, & Donovan, 1978a) and that cries of preterms are more aversive than cries of full-term infants. In a study by Frodi, Lamb, Leavitt, Donovan, Neff, and Sherry (1978b), mothers and fathers were presented with video tapes of crying infants. Half of the viewers observed a full-term newborn, while half observed a preterm infant. Half of the full-term and half of the preterm video tapes carried the cry of a preterm infant, while the other half carded the cry of a full-term infant. The cry of the one preterm infant elicited significantly greater autonomic arosual and was perceived by the mothers and fathers as significantly more aversive than the cry of the term infant. Other recent evidence shows that preterm infants are more irritable (they fuss more and cry more) and less soothable than full-term infants (Friedman, Jacobs, & Werthmann, 1982 b). These differences in how c .rying is expressed by the infant and perceived by the caregiver may potentially lead to differences in the responses of caregivers to full-term infants and to preterm infants. Continuous exposure to aversive cries, especially if these are prolonged and the infant is hard to soothe, may lead to caregivers' physically abusing the crying infant. This possibility is supported by statistics showing that the incidence of child abuse among preterms is higher than what would be expected by chance (Hunter, Kilstrom, Kiaybill, & Loda, 1978; Klein & Stern, 1971; Schmitt & Kempe, 1975). The findings of Frodi et al. (1978b), as described above, have significant implications for the understanding of the interaction of preterms and their caregivers, and therefore have been frequently cited. These findings, however, were not replicated by a later study by Frodi, Lamb, and Willie (1981) in which the stimuli were ostensibly the same as in the Frodi et al. 1978b study. The.importance of the studies by Frodi and her collaborators, as well as methodological problems with the above studies, gave the impetus to our study. Some of the methodological problems are described below~ The Frodi et al. studies have a cry of one preterm and a cry of one full-term as stimuli. Most probably, the cry of the preterm is not representative of all preterm cries: Preterms vary greatly in the degree to which they are at medical risk in the early weeks of their life, and medical risk has been shown t~o affect cry features as well as people's perception of cries (Lester & Zeskind, 1979)-. Also, the cries of the Frodi et al. studies were not of infants of the same age from conception. The difference in the biological/conceptional age of the infants may have determined the findings. The likelihood of finding differences in the behavior of ~|l-term and
PERCEPTIONS OF INFANTS' CRIES
163
preterm infants is increased when the infants are tested at different conceptional ages (e.g., Fantz & Fagan, 1975). The assumptions underlying the present study were (a) that preterm infants do not constitute a homogeneous group and consequently one example of preterm cries does not appropriately represent the domain of such cries, and Co) that results indicating differences in responses to preterm and full-term cries may not allow generalization if the stimulus cries were recorded when the criers were of different conceptional ages. In the present study, women's ratings of cries of four full-term neonates and eight preterms at expected date of birth were compared. Four preterms were of extremely low medical risk in the neonatal period. The other four were of medium medical risk. The work of Frodi et al. (1978b, 1981) suggested that some o f the preterm cries may be rated as more grating and arousing than the full-term cries. The work of Zeskind and Lester (1978) on medical risk and full-term infants' cries suggested that a neonatal history of medical risk in preterm infants might be associated with cries that are perceived as more urgent, grating, sick, and arousing. The purpose of the present study was to compare the responses of women (mothers) to a sample of full-term and preterm cries. The results of the study were expected to shed light on the possible contribution of women's perception of preterm cries to the non-harmonious interactions of some preterm infants with their caregivers. METHOD Subjects Sixty-one women (raters) participated in the study. They were middle-class suburban mothers of children who participated in an ongoing study by Waxier, Chapman, and Yarrow (1979-1980).
Materials The stimuli were two series of six 30-second cries played at a constant level on a cassette recorder. The sound pressure level of the cries was measured with a General Radio Meter Type 1565-A. Scale A of the meter was used since it discriminates heavily against low frequency sounds to give an indication closely correlated with subjective estimates of loudness. The sound pressure level of the cries did not drop below 70dB and did not exceed 90dB. The characteristic variations in the level of the cries ranged between 75dB and 88dB, and were on the average at similar levels.for full-term, low-risk preterm, and moderate-risk preterm cries. The cries in each of the series were elicited during a neurological examination (Howard, Parmelee, Kopp, & Littman, 1976) given when the infants were between 38 and 42 weeks conceptional age (age counted from the last menstrual period of the infants' mothers). The examination was conducted while each of the 12 infants was in a bassinet and the microphone through which the cries were recorded was placed on the mattress to the side of each infant. The cries were selected from cries of 45 black preterm infants and 23 full-term black infants, who were all of similar socio-
164
FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
economic background and who participated in a study by Friedman, Jacobs, and Werthrnann, (1981,'a). The selection of cries was guided by the following criteria: They would include equal numbers of full-term cries, low medical risk preterm cries and moderate-risk preterm cries, and an equal representation of male and female cries in each of the above sub-categories, and they would be cry segments lasting not less than 30 sec. The amount of medical risk associated with the neonatal histories of the preterm infants was estimated by the birthweight, Hobel Infant Risk Score (Hobel, Hyvarinen, Okada, & Oh, 1973), length of hospital stay, and length of intensive care. The moderate medical risk cries were of four infants who were of low birth weight, who had a relatively high infant risk score, whose hospital stay and intensive care were long relative to the 45 preterms in the total sample. The low medical risk cries were of four infants who were at the other extreme of the preterm sample. Table 1 gives some neonatal, day-of-test and maternal variables describing the infants whose cries were used as stimuli in the present study. The stimulus materials were arranged in two series of six cries." Each series TABLE 1 Neonatal, Day-of-Test, and Maternal Variables
Full-Term (n = 4 ) Gestational Age---Birth (weeks) Conceptional A g ~ T e s t (weeks) Weight--Birth (grams) Weight--Test (grams) Apgar--1 min Apgar--5 min Risk Score (Hobel)° Hospital Stay (days) Intensive Care (days) Mother's Age (years) Mother's Education (years) Prenatal Care (1; 2; 3; 4) b
M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D.
40.62 (0.47) 40.62 (0.47) 3,353.00 (275.38) approximately birth weight 9.0 (0.0) 9.2 (0.5) 0.25 (0.50) 1.76 (0.33) 0.0
Low-Risk Pmterm (n = 4 ) 33.75 (3.86) 39.50 (1.00) 2,063.00 (610.51) 3,201.50 (106.42) 7.5 (I .7) 8.8 (0.5) . 13.25 (15.71 ) 14.75 (20.23) 0.0
Medium-Risk Preterm (n = 4 ) 31.87 (2.71) 39.25 (I .89) 1,423.25 (289.00) 2,525.50 (635.00) 4.3 (I .5) (n = 3) 7.3 (0.6) (n = 3) 42.25 (8.77) 44.00
(15.57) 9.00
(0.0)
(0.0)
(4.89)
29.25 (3.94) 13.50 (3.31) 4.0 (0.0)
28.25 (4.57) 12.50 (2.51) 3.75
24.25 (2.21) 13.66 (2.08) (n = 3) 3.66 (0.57) (n = 3)
(0.50)
aHobel, Hyvarinen, Okado, & Oh, 1973 bl = none; 2 = first half pregnancy; 3 = second half pregnancy; 4 = total pregnancy
PERCEPTIONS OF INFANTS' CRIES
165
presented the three types of cries: Full-term (FT), "low medical risk (LR), and medium (or moderate) medical risk (MR). Each series peresented a male and female cry for each of the three cry types. While the individual cries in each series were of different infants, the types of infant cries were the same and appeared in the same order: full-term male, moderate-risk preterm female, low-risk preterm male, fullte/rn female, moderate-risk preterm male and low-risk preterm female.
Experimental Design and Procedure Each of the 12 cries was rated on five 7-point scales. The five scales were: not urgent-urgent; pleasing-grating; healthy-sick; soothing-arousing; mature-immature. The first four scales were previously used by Zeskind and Lester (1978) in a study of adults' perception of neonates' cries. Because the preterm infants whose cries we used were of different health histories, which in turn could affect their maturation, we included also a scale of maturity. Half of the cries were rated on scales going from " l o w " values to " h i g h " values (e.g., soothing-arousing) and the other half on scales going in the opposite direction. The polarity of the scales was alternated on a page-by-page basis on the rating booklet. The ratings were later mcoded so that for the purpose of data analysis they were all coded by the same system. Half of the sample (N = 31) rated cries I through 6 (series 1) first, and then cries 7 through 12 (series 2). The other half of the sample (N = 30) rated cries 7 through 12 first, and then cries 1 through 6. Each woman rated the cries individually in the presence o f a research assistant, who explained the task to her. The assistant was blind to the rationale for the study. The women were told that the purpose of the study was to measure how different cries sound to people by having them judge the cries against a series of descriptive scales. No reference was made to the age of the crying infants or to their gestational or medical status at the neonatal period. Following each woman's rating of the cries, she answered three questions regarding her being distrubed by scratching, shrieking or sudden noises. On the basis of their responses, the women in each study were divided into two groups: a low-sensitivity group and a high-sensitivity group. Eighteen low-sensitivity women and 13 high-sensitivity women rated cries in series 1 first. Sixteen low-sensitivity and 14 high-sensitivity women rated cries in series 2 first. It was thought that sensitivity to unpleasant sounds might interact with the women's ratings of cries, hence that it would be important to control statistically for the effect of the raters' sensitivity. RESULTS Preliminary analyses were conducted to determine the most approp.riate approach to data reduction. The data were analyzed by two repeated measures analyses of variance, one for the data of the women who rated cries 1 through 6 first, and one for the data of the women who rated cries 7 through 12 first. Each analysis had one fixed variable and four repeated variables. The fixed variable was the sensitivity of the raters (low, high). The repeated variables were the rating scales (urgent, grating,
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FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
sick, arousing, immature), the type of cry (full-term, low-risk preterm, medium-risk preterm), the sex of cry" (male, female), and the cry series. Because analyses indicated no effect of rater sensitivity, this variable was not cor!sidered in subsequent analyses. Also, since order of presentation of cries did not influence the ratings, the responses of all 61 raters were pooled. The remaining variables were retained and 10 separate analyses of the 3 factor by 2 factor repeated measures analysis of variance form were performed. In these analyses, the fixed factor consisted of ratings of the 61 women, and the two repeated measures factors were the three types of cries and the two genders of cries (Winer, 1971, pp. 539-599). The t-trst five analyses were of the separate ratings on the dimensions labeled as urgent, grating, sick, arousing, and immature given by the 61 raters to cries 1 through 6 (Series 1). The other five analyses examined the ratings of cries 7 through 12 (Series 2) on these same dimensions. The dependent measures in the above analyses were not independent. Correlations between the ratings given all possible pairs of cries on a given scale were frequently significantly correlated. On scale I ("urgent"), 33 out of 66 correlations were significant; on scale 2 ("grating"), 45 of 66 correlations were significant; on scale 3 ("sick"), 23 out of 66 correlations had ap level smaller than .05; on scale 4 ("arousing"), 33 out of the 66 correlations were significant; on the fifth scale ("immature"), 64 out of 66 correlations were significant. Consequently, conservative degrees of freedom were used fo.r assessing the significance of the results (.Greenhouse & Geisser, 1959). The F values, based on the 10 repeated measures analyses of variance, the conservative degrees of freedom, and the probability level of obtaining such results by chance are presented in Table 2. As can be seen in Table 2, Type-of-cry was a significant variable in the five analyses of the ratings given cries in Series 1. It was significant in four out of five of the analyses of ratings given cries in Series 2: The ratings of the cries on the urgent, grating, sick, and arousing scales were significantly influenced by the type of cries rated in both series. The ratings of cries on the immaturity scale were affected by the type of cry only when the cries of Series 1 were rated. Tukey post hoc contrasts revealed that 12 out of 20 possible contrasts between medium-risk preterm cries and full-term cries were significant: Mediumrisk preterm cries were given higher mean ratings, indicating that they were perceived as more negative sounding than full-term cries. Ten out of 20 possible Tukey contrasts between medium-risk and low-risk preterm cries were significant, showing higher mean ratings for medium-risk than low-risk preterm cries. The contrasts between ratings of low-risk preterm cries and of full-term cries revealed unexpected results: Some low-risk preterm cries were given significantly higher (more "negative" as in more urgent, more sick, etc.) mean ratings than full-term cries. Other low-risk preterm cries were given significantly lower (less "negative," as in less urgent) mean ratings than full-term cries. Low-risk preterm cries Were given significantly higher mean ratings than full-term cries in 7 out of 10 opportunities to rate cries of Series 2. Low-risk preterm cries were given significantly, lower mean ratings than full-term cries in 7 out of 10 opportunities to rate cries in Series 1.
167
PERCEPTIONS OF INFANTS' CRIES TABLE 2* Results of 10 Scale (1) x Type of cry (3) x Sex of cry (2) Analyses of Variance. Given Are the F Values, Conservative Degrees of Freedom and the Probability of Getting the Results by Chance.
Series 1 (cries I-6) conservative
Series 2 (cries 7-12) conservative
Source of
Variation
Scale
F Value
df
P Value
F Value
df
P Value
Urgent
Type of cry Sex of cry Type x Sex
68.72 0.26 26.04
1,60 1,60 1,60
<.0001 n.s <.0001
65.46 15.42 26.56
1,60 1,60 1,60
<.0001 <.001 <.0001
Grating
Type of cry Sex of cry Type X Sex
62.90 12.87 19.58
1,60 1,60 1,60
<.0001 <.001 <.0001
59.06 32.83 10.47
1,60 1,60 1,60
<.0001 <.0001 <.01
Sick
Type of cry Sex of cry Type x Sex
17.12 18.64
2.55
1,60 1,60 1,60
<.001 <.0001 n.s
17.33 8.12 0.43
1,60 1,60 1,60
<.001 <.01 n.s
Arousing
Type of cry Sex of cry Type x Sex
69.79 3.02 13.68
1,60 1,60 1,60
<.0001 n.s <.001
36.10 68.15 18.81 "
1,60 1,60 1,60
<.0001 <.0001 <.0001
Immature
Type of cry Sex of cry Type x Sex
12.91 0.05 5.36
1,60 1,60 1,60
<.001 n.s <.05
3.16 1.86 9.04
1,60 1,60 1,60
n.s n.s <.01
°The Type of cry was a significant variable in repeated measures ANOVAs in which Scale was one of the repeated factors. When chi-square analyses were applied to the frequency distributions of the ratings over cry-types for each of the five scalesand for the five scalescombined--similar results were also obtained (the X2 value was significant).
Figures 1a and 1b present the means of ratings given on each of the five scales to cries in each cry category. The Tukey critical values for testing the post hoc significance of the difference between the ratings given to cries in the cry-type categories are also given in the figures. Table 3 shows the percent of type of cry contrasts which were significant. The analysis of variance also revealed sex-of-cry main effects and sex-of-cry by type-~-cry interactions. The gender of the infant emitting the cry was significant in two out of the five possible analyses of ratings given cries in Series 1: Mothers rated boys' and girls' cries differently on how grating and sick the cries sounded. Sex-ofcry was a significant variable in four out of five analyses pertaining to cries in Series 2: It was a significant variable in all the analyses, except for that of ratings on immaturity of cry (see Table 2). An interaction of Type-of-cry x Sex-of-cry occurred in all analyses, except the ones of ratings given on the sick scale. Male cries were rated with significantly higher (i.e., more "negative" as in more urgent) mean
168
FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
SERIES 1 (cries 1-6) -"URGENT"
71_,,GRATING" .
m r,D
61 m
~m
q,
~f o6
4
t--
! 3 2
I *M F
L
*M F
FULL MEDIUM TERM RISK * ' 1 = 0.85, 2=0.66
]
1
*M F LOW RISK
*M *M FULL MEDIUM TERM RISK *'1 =0.62, 2=0.50
7 ."SICK"
7i "AROUSING" ~
6
6
51
5
I *M F LOW RISK
I,~I ¢,o
=
4
3
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*M F *M FULL MEDIUM TERM RISK *'1=0.96, 2=0.76
*M F LOW RISK
*M F
*M
FULL MEDIUM TERM RISK *'1 = 0.64, 2=0.53
*M LOW RISK
7 "IMMATURE"
8 6 4 "M =Male F = Female
*M F
*M F
FULL MEDIUM TERM RISK *'1 =0.75, 2=0.62
"M F
*'NOTE:I. Tukeycriticalvaluefor determiningthe presermeof significantdiffemnambetween mmn rafln~ of type=of erie=. 2. Tukeyaiticalvaluefor determiningthe pre~'¢e of significantdlffanmcu ratingsof c~m of dlff~ont uDxinfamy_
LOW RISK
Figure 1. Means of ratings given on each of the five scalesto cries in each cry-lype by cry-sex categories. Figure la refers to cries in Series 1. Fibure l b refers to cries in Series 2.
169
PERCEPTIONS OF INFANTS' CRIES SERIES 2 (cries 7-12) "GRATING"
7 "URGENT"
'F 6 5
r... r,,.
¢ou')
03 O: U3
¢'4 r,.
"_.¢
-="i;
r-.
2
*M *M F FULL MEDIUM TERM RISK *'1 = 0.74, 2 = 0.64
*M F LOW RISK
"SICK"
*M F *M F FULL MEDIUM TERM RISK * ' 1 = 0.58, 2=0.46
*M LOW RISK
71_"AROUSING" oO O~
5F
In
4~-
3F 2F
i
*M F *M F FULL MEDIUM TERM RISK *'1=0.85, 2=0.68
*M F LOW RISK
*M F *M F FULL MEDIUM TERM RISK * ' 1 = 0.60, 2=0.48
*M F LOW RISK
7 "IMMATURE" ¢0 GO ¢N
6
5
~
~
m
4 Male F = Fercale
•M =
3 2
" N O T E : 1. Tukey critical value for determining the i ~ u e n c e of significsm differences mean ratings of types of cries, 2. Tukey critical value far detmmining the wesenca of significant d i f f e n m c u between ratings ot cries of different sex infants.
1 *M F *M F FULL MEDIUM TERM RISK *'1=0.66, 2=0.52
*M F LOW RISK
FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
170
TABLE 3 The Percent cff Post I-I0c Type-of-Cry Significant Contrasts (Tukey). Comparisons Are Between Mean Ratings Given the Three Types of Cries Over the Five Scales.
Series I (cries I-6)
Medium-Risk Medium-Risk Low-Risk Low-Risk Full-Term Full-Term
< < < < < <
Series 2 (cries 7-12)
Male Cries
Female Cries
Male Cries
Female
Total
Cries
Total
O0 O0 60 60 O0 O0
O0 O0 100 80 20 80
O0 O0 80 70 10 40
O0 O0 O0 O0 80 60
O0 O0 40 O0 60 100
O0 O0 20 O0 70 80
Full-Term Low-Risk Medium-Risk Full-Term Low-Risk /V~dium-Risk
ratings than female cries when they were the cries of low-risk preterms or of full-term infants. Female cries received significantly higher (more "negative" as in more sick) mean ratings than male cries when the cries were of medium-risk preterm infants (See Table 4). TABLE 4 The Percent of Past Hoc Sex-of-Cry Significant Contrasts (Tukey). Comparisons Are Between Mean Ratings Given Male and Female Cries.
Series 1 (cries 1-6)
Male > Female Female > Male
Series 2 (cries 7-12)
FullTerm
MediumRisk
LowRisk
Total
FullTerm
MediumRisk
LowRisk
Total
O0 O0
O0 60
80 O0
26 20
60 O0
O0 20
60 O0
40 06
Contrary to our expectations, we found that preterm cries are not universally perceived as more urgent, grating, sick, arousing, and immature than full-term infants' cries. Some low-risk preterm cries were rated as less urgent, grating, sick, arousing or immature than full-term cries. Other low-risk preterm cries as well as medium-risk preterm cries were rated as more urgent, grating, sick, arousing or immature than full-term cries. In addition we found that male and female cries were sometimes rated differently and that the direction of the difference varied with the type of cry involved. DISCUSSION Preterm infant cries were not uniformly rated as more urgent, grating, sick arousing or immature than cries of full-term infants of the same conceptional age, and of similar racial and socioeconomic background. While cries of medium-risk infants were consistently rated as the more negative, (e.g., more urgent, grating, sick, arousing, immature) some low-risk preterm cries actually were rated as.less urgent,
PERCEPTIONS OF INFANTS' CRIES
171
more pleasing, healthy, soothing or mature than cries of full-term infants. This composite of findings, therefore, suggests caution in making generalizations about the aversiveness of preterm cries and the corresponding implications for caregiverchild interactions. Frodi et al. (1978b) reported that preterm cries are perceived as more aversive than cries of term infants. Adults' responses to the cry of one preterm infant in the Frodi et al. study might have been dependent on variables other than the cryer's prematurity. The present study suggests that the amount of neonatal medical risk the cryer suffered and the cryer's sex (both unspecified in the Frodi et al. study) could have contributed to the perceived aversiveness of the cry. Our results suggest that cries of preterms who are ostensibly healthy at expected date of birth can reflect the medical risk associated with their neonatal condition: The low-risk preterm cries were frequently rated as less urgent, more pleasing, healthy, soothing or mature than cries of the medium-risk preterm infants. This findin~ is reminiscent of the finding of Zeskind and Lester (1978) and Zeskind (1980) showing that medical risk associated with the pregenancy of women was reflected in the perceived qualities of the cries of their healthy newborns. In the case of this study it is possible that even though all the preterm subjects were assumed to be equally well, the low-risk group may have made a more rapid recovery from the stress of preterm birth. The mechanism through which a history of medical risk affects features of the cry signal are not known. The full-term male cries and the low-risk preterm male cries were sometimes given significantly higher (more "negative" as in more urgent) mean ratings than the respective female cries, The direction of the sex differences was reversed in the case of the medium-risk preterm cries. The small number of cries in each cry-type x cry-sex category does not permit the formal testing of a hypothesis we have regarding the source of the cry-type by cry-sex interaction. We would speculate, however, that the interaction is due to the association between fetal and neonatal medical risk, the perceived qualities of the cries as shown by Zeskind and Lester (1978), and in this study. In the general population male infants are at greater risk for mortality and morbidity than female infants (Graham, Ernhart, Thurston, & Craft, 1962; Huntingford, 1963; Ucko, 1965; Taffel, 1978; U. S. Vital Statistics, 1975). This greater risk which is associated with being a male infant may express itself in male infants' cries, and consequently lead to more conceptually "negative" perceptions of their cries. Still unanswered, however, is the question of why medium-risk female cries are perceived as more negative than the cries of their male counterparts. This study was partially undertaken in an attempt to provide evidence ~or the hypothesis that the less optimal interaction between preterms and. their caregivers, often described in the literature, is partially influenced by behaviors of the preterm infants. On the basis of conflicting and methodologically problematic existing research results (described in the introduction), it was suggested that the cries of preterms might be perceived as more urgent, grating, arousing, sick, and immature sounding than cries of full-term infants of the same conceptional age, race, and socioeconomic background. While support for this suggestion was found when medium-risk infant cries were used, another set of findings was contrary to this
FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
172
suggestion; low-risk infant cries were rated as either more or less urgent, grating, sick, etc., than cires of full-term infants. This latter finding invites further speculation about cry features as communications that influence" infant care. On the one hand, a pleasant sounding cry of a preterm infant may be as maladaptive as an unpleasant cry. The pleasant cry may lead to neglect, the unpleasant cry to abuse. On the other hand, the pleasant cry may invite more positive interactions from caregivers, thus promoting healthy development. The present research design does not permit testing of these alternatives. Combinations of naturalistic and experimental research designs will be necessary to address some of these issues. Further, it will be important to document the relationship between cry features (physical features and perceived features) and caregivers' responsiveness to crying infants. The research paradigm employed here is in the traditino of designs typically used to investigate the influence of infant cries on caregivers. While the cries used in the present study represented a range of preterm and full-term infants' cries, the sample of stimuli was undoubtedly not entirely representative of full-term and preterm infants cries. Cries were collected under the stress of a neurological exam, they were listened to in the absence of the cryers through a cassette recorder, and they were rated by women who were not at the time responsible for the care of the cryers or other young infants. The perceived qualities of preterm cries and their contribution to optimal infant caregiver relationships needs to be conceptualized and studied in a framework which takes into account a panorama of infant behaviors (e.g., Brazelton, 1973). Features of the naturalistic caregiving environment (Lester & Zeskind, 1979) that promote or hinder healthy development will ultimately need to be investigated if we are to understand fully the interplay of infant affect and stress with adaptive and maladaptive parent-child interaction. REFERENCES Barnett, C. R., Leidarman, P. H., Grobstein, R., & Klaus, M. H. Neonatal separation: The maternal side of interactional deprivation. Pediatrics, 1970, 45, 197-205. Bell, R. Q. Parent, child, and reciprocal influences. American Psychologist, 1979, 34, 821-826. Bowlby, J. Attachment and loss (Vol. 1). New York: Basic Books, 1969. Brazelton, T. B. Neonatal behavior assessment scale. Philadelphia: J. B. Lippincott, 1973.
David, M., & Appell, G. A study of nursing care and nurse-infant interaction. In B. M. Foss (Ed.), Determinants of infant behavior. New York: John Wiley & Sons, Inc. 1961. Emda, R. N., Gacnsbauer, T. J., & Harmon, R. I. Emotionc~l expression in infancy. New York: International Universities Press, Inc., 1976. Fantz, R. L., & Fagan, J. F., III. Visual attention to size and number of pattern details by term and preterm infants during the fast six months. Child Development, 1975, 46, 3-18. Field, T. M., Goldberg, S., Stern, D., & Sostek, A. M. High-risk infants and children. New York: Acadamie Press, 1980. Friedman, S. L., Jacobs, B. S., & Werthmarm, M. W., Jr. Sensory processing in preterm and full-term infants at the neonatal period. In S. L. Friedman & M. Sigman (Eds.), Preterm birth and psychological development. New York: Academic Press, 1981. (a) Friedman, S. L., Ja¢obs, B. S., & Werthmarm, M. W., Jr. Preterras of low medical risk: Spontaneous behaviors and soothability at expected date of birth. Infant Behavior and Development, 1982, 5,
3-10. (b)
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Frodi, A. M., Lamb, M. E., Leavitt, L. A., & Donovan, W. L. Fathers' and mothers' responses to infant smiles and cries. Infant Behavior and Development, 1978, I, 187-198. (a) Frodi, A. M., Laml~, M. E., Leavitt, L. A., Donovan, W. L., Neff, C., & Sherry, D. Fathers' and mothers" responses to the faces and cries of normal and premature infants. Developmental Po'chology, 1978, 14, 490-498. (b) Frodi, A. M., Lamb, M. E., & Willie, D. Mothers' responses to cries of normal end premature infants as a function of birth status of their own child. Journal of Research in Personality, 1981, 15, 122-133. Goldberg, S. Prematurity: Effects on parent-infant interaction. Journal of Pediatric Psychology, 1978,3, 137-144. Graham, F. K., Ernhart, C. B., Thurston, D., & Craft, M. Development three years after perinatal anoxia and other potentially damaging newborn experiences. Psychological Monographs, 1962, 76 (Whole No. 522~. Greenhouse, S. W., & Geisser, S. On methods in the analysis of profile data. Psychometrika, 1959, 24, 95-112. Hobel, C. J., Hyvarinen, M. A., Okada, D. M., & Oh, W. Prenatal and intrapartum high risk screening. American Journal of Obstetrics and Gynecology, 1973, 117, 1-19. Howard, J., Parmalee, A. H., Kopp, C. B., & Littman, B. A neurological comparison of preterm and full-term infants at term conceptional age. The Journal of Pediatrics, 1976, 88, 995-1002. Hunter, R. S., Kilstrom, N., Kraybill, E. N., & Loda. F. Antecedents of child abuse and neglect in premature infants: A prospective study in a newborn intensive care unit. Pediatrics, 1978, 61, 629-635. Huntingford, P. J. Influence of anaesthesia on the incidence of maternal morbidity, neonatal asphyxia, and preinatal mortality. British Medical Journal, 1963, I, ! 195-1199. Klein, M., & Stern, L. Low birthweight and battered child syndrome. American Journal of Diseases of Children, 1971, I22, 15-18. Lester, B. M., & Zeskind, P. S. The organization of crying in the infant at risk. In T. M. Field, A. M. Sostek, S. Goldberg, & H. H. Shnman (Eds.), Infants born at risk. Washington, DC: Spectrum Books, 1979. Lewis, M., & Rosenbinm, L. A. The effect of the infant on its caregiver. New York: John Wiley and Sons, 1974. Murray, A. D. Infant crying as an elicitor of parental behavior: An examination of twn models. Psychological Bulletin, 1979, 86, 191-215. Schmitt, B., & Kempe, H. Neglect and abuse of children. In V. Vaughan, I I I & R. J. McKay (Eds.), Nelson Textbook of Pediatrics, 10th Edition. Philadelphia: Saunders Co., 1975. Taffel, S. M. Congenital anomalies and birth injuries among live births: United States, 1973-1974. Hyattsville, MD, U.S. DHEW PHS, National Center for Health Statistics, 1978. Ucko, L. E. A comparative study of asphyxiated and non-asphyxiated boys from birth to five years. Developmental Medicine and Child Neurology, 1965, 7, 643-657. U. S. Vital Statistics. Mortality, Part A (Vol. 2). Tables 2-2, 2-14, 1975. Waxier, C. Z., Chapman, M., & Yarrow, M. R. Prosocial behavior, cognitive development, and moral reasoning: An ongoing research project, Laboratory of Developmental Psychology, National Institute of Mental Health. 1979-1980. Winer. B. Statistical principles in experimental design. New York: McGraw-Hill, 1971. Zeskihd, P. S. Adult responses to cries of low and high risk infants. Infant Behavior and Development, 1980, 3, 167-177. Zeskind, P. S., & Lester, B. M. Acoustic features and auditory perceptions of the cries of newborns with prenatal and perinatral complications. Child Development, 1978, 49, 580-589.
Perceptions of Cries of Full-term and Preterm Infants* SARAH L. FRIEDMAN, CAROLYN ZAHN-WAXLER, AND MARIAN RADKE-YARROW
National Institute o f Mental Health Bethesda. MD 20205 Sixty-one mothers rated 12 infant cries. There were four cries (30 sac each) of healthy full-term neonates, four cires of very low-risk preterm infants, and four tires of medium-risk preterm infants. The cries were each rated on five 7-point scales with the conceptually "negative" polarity representing the urgent, grating, sick, arousing, and immature qualities of cries. Preterm tires were not uniformly rated as more urgent, grating, sick, arousing or immature than cries of full-term infants of the same conceptional age and of similar racial and socioeconomic background. Some preterm cries were rated as significantly more urgent, grating, sick, arousing or immature than full-term cries; other preterm cires were rated as significantly less urgent, etc., than full-term cries. Even though all the preterm infants were ostensibly healthy when their cries were recorded at expected date of birth, the ratings of the cries were related to the medical risk associated with the cryers' neonatal medical condition. The findings have implications for future research regarding cry features as adaptive ancl maladaptive communications that influence infants' development.
Mothers of preterm and full-term infants do not interact with their infants in the same way (Goldberg, 1978; Field, Goldberg, Stem, & Sostek, 1980). The interaction between preterm infants and their caregivers is believed to be less optimal than the interaction of full-term infants with their mothers. The less than optimal interaction in the preterms-mothers dyads is often attributed to the disruption of the bonding or attachment process due to separation between preterms and their mothers while the infants are in the hospital for intensive care (Barnett, Leidermann, Grobstein, & Klaus, 1970). It is reasonable to assume, however, that another contributor to caregivers' social interaction with preterms is the behavior of the preterms themselves. Infants' and children's behaviors are k n o w n to influence the behaviors of their caregivers toward them (Lewis & Rosenblum, 1974; Bell, 1979). A n example of infant behavior which is frequent and affects caregivers is crying (Bowlby, 1969; David & Appell, 1961; Erode, Gaensbauer, & Harmon, * Manyindividualshelped to makethis studypossible. MiltonWerthmann,of the WashingtonHospitalCentergave us accessto a populationof full-termand preterminfants.Mrs. AnneMayfieldrecruitedthe infants,Mrs. Blanche Jacobsassistedwiththe recordingof the cries. Mrs.GeriCoopermanand Mrs. JeanDarbyWelshrecruitedthe mothers who rated the cries and explainedthe procedures to them. Miss ChristineDavenportceded the data. John Bartko monitoredour choiceof statisticalmethodsand Mrs. JeanDarbyWelshwas involvedwiththe analysisof the data. Mrs. Eunice Keanellyand Mrs. Bertha LeCompte typed the manuscript.We thank these individualsfor their valuable contributionsand dedicatedinvolvementin the study.Correspondenceand requestsfor reprintsshouldbe addressedto: Sarah L. Friedman,NationalInstituteof Education, 1200 19 Street,N.W. Washington,DC 20208. 161
162
FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
1976; Murray, 1979). Crying provides a means of communication about the infant's needs. It is, simultaneously, an expression of affect that can impinge positively or negatively upon the caregiver. It can elicit the caregiver's comforting responses (Zeskind, 1980), and through the caregiver's responding to it, the attachment bond between infant and caregiver can grow. Consequently, if an infant's cries are for some reason unusual, they may have an impact on the quality of the interaction between the infant and the caregiver. It also follows that if preterms' cries are preceived as more negative sounding than cries of full-term infants, caregivers may respond to preterms differently from the way they respond to full-term infants. There is evidence to show that infant cries can be perceived as aversive stimuli (Frodi, Lamb, Leavitt, & Donovan, 1978a) and that cries of preterms are more aversive than cries of full-term infants. In a study by Frodi, Lamb, Leavitt, Donovan, Neff, and Sherry (1978b), mothers and fathers were presented with video tapes of crying infants. Half of the viewers observed a full-term newborn, while half observed a preterm infant. Half of the full-term and half of the preterm video tapes carried the cry of a preterm infant, while the other half carded the cry of a full-term infant. The cry of the one preterm infant elicited significantly greater autonomic arosual and was perceived by the mothers and fathers as significantly more aversive than the cry of the term infant. Other recent evidence shows that preterm infants are more irritable (they fuss more and cry more) and less soothable than full-term infants (Friedman, Jacobs, & Werthmann, 1982 b). These differences in how c .rying is expressed by the infant and perceived by the caregiver may potentially lead to differences in the responses of caregivers to full-term infants and to preterm infants. Continuous exposure to aversive cries, especially if these are prolonged and the infant is hard to soothe, may lead to caregivers' physically abusing the crying infant. This possibility is supported by statistics showing that the incidence of child abuse among preterms is higher than what would be expected by chance (Hunter, Kilstrom, Kiaybill, & Loda, 1978; Klein & Stern, 1971; Schmitt & Kempe, 1975). The findings of Frodi et al. (1978b), as described above, have significant implications for the understanding of the interaction of preterms and their caregivers, and therefore have been frequently cited. These findings, however, were not replicated by a later study by Frodi, Lamb, and Willie (1981) in which the stimuli were ostensibly the same as in the Frodi et al. 1978b study. The.importance of the studies by Frodi and her collaborators, as well as methodological problems with the above studies, gave the impetus to our study. Some of the methodological problems are described below~ The Frodi et al. studies have a cry of one preterm and a cry of one full-term as stimuli. Most probably, the cry of the preterm is not representative of all preterm cries: Preterms vary greatly in the degree to which they are at medical risk in the early weeks of their life, and medical risk has been shown t~o affect cry features as well as people's perception of cries (Lester & Zeskind, 1979)-. Also, the cries of the Frodi et al. studies were not of infants of the same age from conception. The difference in the biological/conceptional age of the infants may have determined the findings. The likelihood of finding differences in the behavior of ~|l-term and
PERCEPTIONS OF INFANTS' CRIES
163
preterm infants is increased when the infants are tested at different conceptional ages (e.g., Fantz & Fagan, 1975). The assumptions underlying the present study were (a) that preterm infants do not constitute a homogeneous group and consequently one example of preterm cries does not appropriately represent the domain of such cries, and Co) that results indicating differences in responses to preterm and full-term cries may not allow generalization if the stimulus cries were recorded when the criers were of different conceptional ages. In the present study, women's ratings of cries of four full-term neonates and eight preterms at expected date of birth were compared. Four preterms were of extremely low medical risk in the neonatal period. The other four were of medium medical risk. The work of Frodi et al. (1978b, 1981) suggested that some o f the preterm cries may be rated as more grating and arousing than the full-term cries. The work of Zeskind and Lester (1978) on medical risk and full-term infants' cries suggested that a neonatal history of medical risk in preterm infants might be associated with cries that are perceived as more urgent, grating, sick, and arousing. The purpose of the present study was to compare the responses of women (mothers) to a sample of full-term and preterm cries. The results of the study were expected to shed light on the possible contribution of women's perception of preterm cries to the non-harmonious interactions of some preterm infants with their caregivers. METHOD Subjects Sixty-one women (raters) participated in the study. They were middle-class suburban mothers of children who participated in an ongoing study by Waxier, Chapman, and Yarrow (1979-1980).
Materials The stimuli were two series of six 30-second cries played at a constant level on a cassette recorder. The sound pressure level of the cries was measured with a General Radio Meter Type 1565-A. Scale A of the meter was used since it discriminates heavily against low frequency sounds to give an indication closely correlated with subjective estimates of loudness. The sound pressure level of the cries did not drop below 70dB and did not exceed 90dB. The characteristic variations in the level of the cries ranged between 75dB and 88dB, and were on the average at similar levels.for full-term, low-risk preterm, and moderate-risk preterm cries. The cries in each of the series were elicited during a neurological examination (Howard, Parmelee, Kopp, & Littman, 1976) given when the infants were between 38 and 42 weeks conceptional age (age counted from the last menstrual period of the infants' mothers). The examination was conducted while each of the 12 infants was in a bassinet and the microphone through which the cries were recorded was placed on the mattress to the side of each infant. The cries were selected from cries of 45 black preterm infants and 23 full-term black infants, who were all of similar socio-
164
FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
economic background and who participated in a study by Friedman, Jacobs, and Werthrnann, (1981,'a). The selection of cries was guided by the following criteria: They would include equal numbers of full-term cries, low medical risk preterm cries and moderate-risk preterm cries, and an equal representation of male and female cries in each of the above sub-categories, and they would be cry segments lasting not less than 30 sec. The amount of medical risk associated with the neonatal histories of the preterm infants was estimated by the birthweight, Hobel Infant Risk Score (Hobel, Hyvarinen, Okada, & Oh, 1973), length of hospital stay, and length of intensive care. The moderate medical risk cries were of four infants who were of low birth weight, who had a relatively high infant risk score, whose hospital stay and intensive care were long relative to the 45 preterms in the total sample. The low medical risk cries were of four infants who were at the other extreme of the preterm sample. Table 1 gives some neonatal, day-of-test and maternal variables describing the infants whose cries were used as stimuli in the present study. The stimulus materials were arranged in two series of six cries." Each series TABLE 1 Neonatal, Day-of-Test, and Maternal Variables
Full-Term (n = 4 ) Gestational Age---Birth (weeks) Conceptional A g ~ T e s t (weeks) Weight--Birth (grams) Weight--Test (grams) Apgar--1 min Apgar--5 min Risk Score (Hobel)° Hospital Stay (days) Intensive Care (days) Mother's Age (years) Mother's Education (years) Prenatal Care (1; 2; 3; 4) b
M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D. M S.D.
40.62 (0.47) 40.62 (0.47) 3,353.00 (275.38) approximately birth weight 9.0 (0.0) 9.2 (0.5) 0.25 (0.50) 1.76 (0.33) 0.0
Low-Risk Pmterm (n = 4 ) 33.75 (3.86) 39.50 (1.00) 2,063.00 (610.51) 3,201.50 (106.42) 7.5 (I .7) 8.8 (0.5) . 13.25 (15.71 ) 14.75 (20.23) 0.0
Medium-Risk Preterm (n = 4 ) 31.87 (2.71) 39.25 (I .89) 1,423.25 (289.00) 2,525.50 (635.00) 4.3 (I .5) (n = 3) 7.3 (0.6) (n = 3) 42.25 (8.77) 44.00
(15.57) 9.00
(0.0)
(0.0)
(4.89)
29.25 (3.94) 13.50 (3.31) 4.0 (0.0)
28.25 (4.57) 12.50 (2.51) 3.75
24.25 (2.21) 13.66 (2.08) (n = 3) 3.66 (0.57) (n = 3)
(0.50)
aHobel, Hyvarinen, Okado, & Oh, 1973 bl = none; 2 = first half pregnancy; 3 = second half pregnancy; 4 = total pregnancy
PERCEPTIONS OF INFANTS' CRIES
165
presented the three types of cries: Full-term (FT), "low medical risk (LR), and medium (or moderate) medical risk (MR). Each series peresented a male and female cry for each of the three cry types. While the individual cries in each series were of different infants, the types of infant cries were the same and appeared in the same order: full-term male, moderate-risk preterm female, low-risk preterm male, fullte/rn female, moderate-risk preterm male and low-risk preterm female.
Experimental Design and Procedure Each of the 12 cries was rated on five 7-point scales. The five scales were: not urgent-urgent; pleasing-grating; healthy-sick; soothing-arousing; mature-immature. The first four scales were previously used by Zeskind and Lester (1978) in a study of adults' perception of neonates' cries. Because the preterm infants whose cries we used were of different health histories, which in turn could affect their maturation, we included also a scale of maturity. Half of the cries were rated on scales going from " l o w " values to " h i g h " values (e.g., soothing-arousing) and the other half on scales going in the opposite direction. The polarity of the scales was alternated on a page-by-page basis on the rating booklet. The ratings were later mcoded so that for the purpose of data analysis they were all coded by the same system. Half of the sample (N = 31) rated cries I through 6 (series 1) first, and then cries 7 through 12 (series 2). The other half of the sample (N = 30) rated cries 7 through 12 first, and then cries 1 through 6. Each woman rated the cries individually in the presence o f a research assistant, who explained the task to her. The assistant was blind to the rationale for the study. The women were told that the purpose of the study was to measure how different cries sound to people by having them judge the cries against a series of descriptive scales. No reference was made to the age of the crying infants or to their gestational or medical status at the neonatal period. Following each woman's rating of the cries, she answered three questions regarding her being distrubed by scratching, shrieking or sudden noises. On the basis of their responses, the women in each study were divided into two groups: a low-sensitivity group and a high-sensitivity group. Eighteen low-sensitivity women and 13 high-sensitivity women rated cries in series 1 first. Sixteen low-sensitivity and 14 high-sensitivity women rated cries in series 2 first. It was thought that sensitivity to unpleasant sounds might interact with the women's ratings of cries, hence that it would be important to control statistically for the effect of the raters' sensitivity. RESULTS Preliminary analyses were conducted to determine the most approp.riate approach to data reduction. The data were analyzed by two repeated measures analyses of variance, one for the data of the women who rated cries 1 through 6 first, and one for the data of the women who rated cries 7 through 12 first. Each analysis had one fixed variable and four repeated variables. The fixed variable was the sensitivity of the raters (low, high). The repeated variables were the rating scales (urgent, grating,
166
FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
sick, arousing, immature), the type of cry (full-term, low-risk preterm, medium-risk preterm), the sex of cry" (male, female), and the cry series. Because analyses indicated no effect of rater sensitivity, this variable was not cor!sidered in subsequent analyses. Also, since order of presentation of cries did not influence the ratings, the responses of all 61 raters were pooled. The remaining variables were retained and 10 separate analyses of the 3 factor by 2 factor repeated measures analysis of variance form were performed. In these analyses, the fixed factor consisted of ratings of the 61 women, and the two repeated measures factors were the three types of cries and the two genders of cries (Winer, 1971, pp. 539-599). The t-trst five analyses were of the separate ratings on the dimensions labeled as urgent, grating, sick, arousing, and immature given by the 61 raters to cries 1 through 6 (Series 1). The other five analyses examined the ratings of cries 7 through 12 (Series 2) on these same dimensions. The dependent measures in the above analyses were not independent. Correlations between the ratings given all possible pairs of cries on a given scale were frequently significantly correlated. On scale I ("urgent"), 33 out of 66 correlations were significant; on scale 2 ("grating"), 45 of 66 correlations were significant; on scale 3 ("sick"), 23 out of 66 correlations had ap level smaller than .05; on scale 4 ("arousing"), 33 out of the 66 correlations were significant; on the fifth scale ("immature"), 64 out of 66 correlations were significant. Consequently, conservative degrees of freedom were used fo.r assessing the significance of the results (.Greenhouse & Geisser, 1959). The F values, based on the 10 repeated measures analyses of variance, the conservative degrees of freedom, and the probability level of obtaining such results by chance are presented in Table 2. As can be seen in Table 2, Type-of-cry was a significant variable in the five analyses of the ratings given cries in Series 1. It was significant in four out of five of the analyses of ratings given cries in Series 2: The ratings of the cries on the urgent, grating, sick, and arousing scales were significantly influenced by the type of cries rated in both series. The ratings of cries on the immaturity scale were affected by the type of cry only when the cries of Series 1 were rated. Tukey post hoc contrasts revealed that 12 out of 20 possible contrasts between medium-risk preterm cries and full-term cries were significant: Mediumrisk preterm cries were given higher mean ratings, indicating that they were perceived as more negative sounding than full-term cries. Ten out of 20 possible Tukey contrasts between medium-risk and low-risk preterm cries were significant, showing higher mean ratings for medium-risk than low-risk preterm cries. The contrasts between ratings of low-risk preterm cries and of full-term cries revealed unexpected results: Some low-risk preterm cries were given significantly higher (more "negative" as in more urgent, more sick, etc.) mean ratings than full-term cries. Other low-risk preterm cries were given significantly lower (less "negative," as in less urgent) mean ratings than full-term cries. Low-risk preterm cries Were given significantly higher mean ratings than full-term cries in 7 out of 10 opportunities to rate cries of Series 2. Low-risk preterm cries were given significantly, lower mean ratings than full-term cries in 7 out of 10 opportunities to rate cries in Series 1.
167
PERCEPTIONS OF INFANTS' CRIES TABLE 2* Results of 10 Scale (1) x Type of cry (3) x Sex of cry (2) Analyses of Variance. Given Are the F Values, Conservative Degrees of Freedom and the Probability of Getting the Results by Chance.
Series 1 (cries I-6) conservative
Series 2 (cries 7-12) conservative
Source of
Variation
Scale
F Value
df
P Value
F Value
df
P Value
Urgent
Type of cry Sex of cry Type x Sex
68.72 0.26 26.04
1,60 1,60 1,60
<.0001 n.s <.0001
65.46 15.42 26.56
1,60 1,60 1,60
<.0001 <.001 <.0001
Grating
Type of cry Sex of cry Type X Sex
62.90 12.87 19.58
1,60 1,60 1,60
<.0001 <.001 <.0001
59.06 32.83 10.47
1,60 1,60 1,60
<.0001 <.0001 <.01
Sick
Type of cry Sex of cry Type x Sex
17.12 18.64
2.55
1,60 1,60 1,60
<.001 <.0001 n.s
17.33 8.12 0.43
1,60 1,60 1,60
<.001 <.01 n.s
Arousing
Type of cry Sex of cry Type x Sex
69.79 3.02 13.68
1,60 1,60 1,60
<.0001 n.s <.001
36.10 68.15 18.81 "
1,60 1,60 1,60
<.0001 <.0001 <.0001
Immature
Type of cry Sex of cry Type x Sex
12.91 0.05 5.36
1,60 1,60 1,60
<.001 n.s <.05
3.16 1.86 9.04
1,60 1,60 1,60
n.s n.s <.01
°The Type of cry was a significant variable in repeated measures ANOVAs in which Scale was one of the repeated factors. When chi-square analyses were applied to the frequency distributions of the ratings over cry-types for each of the five scalesand for the five scalescombined--similar results were also obtained (the X2 value was significant).
Figures 1a and 1b present the means of ratings given on each of the five scales to cries in each cry category. The Tukey critical values for testing the post hoc significance of the difference between the ratings given to cries in the cry-type categories are also given in the figures. Table 3 shows the percent of type of cry contrasts which were significant. The analysis of variance also revealed sex-of-cry main effects and sex-of-cry by type-~-cry interactions. The gender of the infant emitting the cry was significant in two out of the five possible analyses of ratings given cries in Series 1: Mothers rated boys' and girls' cries differently on how grating and sick the cries sounded. Sex-ofcry was a significant variable in four out of five analyses pertaining to cries in Series 2: It was a significant variable in all the analyses, except for that of ratings on immaturity of cry (see Table 2). An interaction of Type-of-cry x Sex-of-cry occurred in all analyses, except the ones of ratings given on the sick scale. Male cries were rated with significantly higher (i.e., more "negative" as in more urgent) mean
168
FRIEDMAN, ZAHN-WALKER, AND RADKE-YARROW
SERIES 1 (cries 1-6) -"URGENT"
71_,,GRATING" .
m r,D
61 m
~m
q,
~f o6
4
t--
! 3 2
I *M F
L
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FULL MEDIUM TERM RISK * ' 1 = 0.85, 2=0.66
]
1
*M F LOW RISK
*M *M FULL MEDIUM TERM RISK *'1 =0.62, 2=0.50
7 ."SICK"
7i "AROUSING" ~
6
6
51
5
I *M F LOW RISK
I,~I ¢,o
=
4
3
3
2
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*M F *M FULL MEDIUM TERM RISK *'1=0.96, 2=0.76
*M F LOW RISK
*M F
*M
FULL MEDIUM TERM RISK *'1 = 0.64, 2=0.53
*M LOW RISK
7 "IMMATURE"
8 6 4 "M =Male F = Female
*M F
*M F
FULL MEDIUM TERM RISK *'1 =0.75, 2=0.62
"M F
*'NOTE:I. Tukeycriticalvaluefor determiningthe presermeof significantdiffemnambetween mmn rafln~ of type=of erie=. 2. Tukeyaiticalvaluefor determiningthe pre~'¢e of significantdlffanmcu ratingsof c~m of dlff~ont uDxinfamy_
LOW RISK
Figure 1. Means of ratings given on each of the five scalesto cries in each cry-lype by cry-sex categories. Figure la refers to cries in Series 1. Fibure l b refers to cries in Series 2.
169
PERCEPTIONS OF INFANTS' CRIES SERIES 2 (cries 7-12) "GRATING"
7 "URGENT"
'F 6 5
r... r,,.
¢ou')
03 O: U3
¢'4 r,.
"_.¢
-="i;
r-.
2
*M *M F FULL MEDIUM TERM RISK *'1 = 0.74, 2 = 0.64
*M F LOW RISK
"SICK"
*M F *M F FULL MEDIUM TERM RISK * ' 1 = 0.58, 2=0.46
*M LOW RISK
71_"AROUSING" oO O~
5F
In
4~-
3F 2F
i
*M F *M F FULL MEDIUM TERM RISK *'1=0.85, 2=0.68
*M F LOW RISK
*M F *M F FULL MEDIUM TERM RISK * ' 1 = 0.60, 2=0.48
*M F LOW RISK
7 "IMMATURE" ¢0 GO ¢N
6
5
~
~
m
4 Male F = Fercale
•M =
3 2
" N O T E : 1. Tukey critical value for determining the i ~ u e n c e of significsm differences mean ratings of types of cries, 2. Tukey critical value far detmmining the wesenca of significant d i f f e n m c u between ratings ot cries of different sex infants.
1 *M F *M F FULL MEDIUM TERM RISK *'1=0.66, 2=0.52
*M F LOW RISK
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170
TABLE 3 The Percent cff Post I-I0c Type-of-Cry Significant Contrasts (Tukey). Comparisons Are Between Mean Ratings Given the Three Types of Cries Over the Five Scales.
Series I (cries I-6)
Medium-Risk Medium-Risk Low-Risk Low-Risk Full-Term Full-Term
< < < < < <
Series 2 (cries 7-12)
Male Cries
Female Cries
Male Cries
Female
Total
Cries
Total
O0 O0 60 60 O0 O0
O0 O0 100 80 20 80
O0 O0 80 70 10 40
O0 O0 O0 O0 80 60
O0 O0 40 O0 60 100
O0 O0 20 O0 70 80
Full-Term Low-Risk Medium-Risk Full-Term Low-Risk /V~dium-Risk
ratings than female cries when they were the cries of low-risk preterms or of full-term infants. Female cries received significantly higher (more "negative" as in more sick) mean ratings than male cries when the cries were of medium-risk preterm infants (See Table 4). TABLE 4 The Percent of Past Hoc Sex-of-Cry Significant Contrasts (Tukey). Comparisons Are Between Mean Ratings Given Male and Female Cries.
Series 1 (cries 1-6)
Male > Female Female > Male
Series 2 (cries 7-12)
FullTerm
MediumRisk
LowRisk
Total
FullTerm
MediumRisk
LowRisk
Total
O0 O0
O0 60
80 O0
26 20
60 O0
O0 20
60 O0
40 06
Contrary to our expectations, we found that preterm cries are not universally perceived as more urgent, grating, sick, arousing, and immature than full-term infants' cries. Some low-risk preterm cries were rated as less urgent, grating, sick, arousing or immature than full-term cries. Other low-risk preterm cries as well as medium-risk preterm cries were rated as more urgent, grating, sick, arousing or immature than full-term cries. In addition we found that male and female cries were sometimes rated differently and that the direction of the difference varied with the type of cry involved. DISCUSSION Preterm infant cries were not uniformly rated as more urgent, grating, sick arousing or immature than cries of full-term infants of the same conceptional age, and of similar racial and socioeconomic background. While cries of medium-risk infants were consistently rated as the more negative, (e.g., more urgent, grating, sick, arousing, immature) some low-risk preterm cries actually were rated as.less urgent,
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171
more pleasing, healthy, soothing or mature than cries of full-term infants. This composite of findings, therefore, suggests caution in making generalizations about the aversiveness of preterm cries and the corresponding implications for caregiverchild interactions. Frodi et al. (1978b) reported that preterm cries are perceived as more aversive than cries of term infants. Adults' responses to the cry of one preterm infant in the Frodi et al. study might have been dependent on variables other than the cryer's prematurity. The present study suggests that the amount of neonatal medical risk the cryer suffered and the cryer's sex (both unspecified in the Frodi et al. study) could have contributed to the perceived aversiveness of the cry. Our results suggest that cries of preterms who are ostensibly healthy at expected date of birth can reflect the medical risk associated with their neonatal condition: The low-risk preterm cries were frequently rated as less urgent, more pleasing, healthy, soothing or mature than cries of the medium-risk preterm infants. This findin~ is reminiscent of the finding of Zeskind and Lester (1978) and Zeskind (1980) showing that medical risk associated with the pregenancy of women was reflected in the perceived qualities of the cries of their healthy newborns. In the case of this study it is possible that even though all the preterm subjects were assumed to be equally well, the low-risk group may have made a more rapid recovery from the stress of preterm birth. The mechanism through which a history of medical risk affects features of the cry signal are not known. The full-term male cries and the low-risk preterm male cries were sometimes given significantly higher (more "negative" as in more urgent) mean ratings than the respective female cries, The direction of the sex differences was reversed in the case of the medium-risk preterm cries. The small number of cries in each cry-type x cry-sex category does not permit the formal testing of a hypothesis we have regarding the source of the cry-type by cry-sex interaction. We would speculate, however, that the interaction is due to the association between fetal and neonatal medical risk, the perceived qualities of the cries as shown by Zeskind and Lester (1978), and in this study. In the general population male infants are at greater risk for mortality and morbidity than female infants (Graham, Ernhart, Thurston, & Craft, 1962; Huntingford, 1963; Ucko, 1965; Taffel, 1978; U. S. Vital Statistics, 1975). This greater risk which is associated with being a male infant may express itself in male infants' cries, and consequently lead to more conceptually "negative" perceptions of their cries. Still unanswered, however, is the question of why medium-risk female cries are perceived as more negative than the cries of their male counterparts. This study was partially undertaken in an attempt to provide evidence ~or the hypothesis that the less optimal interaction between preterms and. their caregivers, often described in the literature, is partially influenced by behaviors of the preterm infants. On the basis of conflicting and methodologically problematic existing research results (described in the introduction), it was suggested that the cries of preterms might be perceived as more urgent, grating, arousing, sick, and immature sounding than cries of full-term infants of the same conceptional age, race, and socioeconomic background. While support for this suggestion was found when medium-risk infant cries were used, another set of findings was contrary to this
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172
suggestion; low-risk infant cries were rated as either more or less urgent, grating, sick, etc., than cires of full-term infants. This latter finding invites further speculation about cry features as communications that influence" infant care. On the one hand, a pleasant sounding cry of a preterm infant may be as maladaptive as an unpleasant cry. The pleasant cry may lead to neglect, the unpleasant cry to abuse. On the other hand, the pleasant cry may invite more positive interactions from caregivers, thus promoting healthy development. The present research design does not permit testing of these alternatives. Combinations of naturalistic and experimental research designs will be necessary to address some of these issues. Further, it will be important to document the relationship between cry features (physical features and perceived features) and caregivers' responsiveness to crying infants. The research paradigm employed here is in the traditino of designs typically used to investigate the influence of infant cries on caregivers. While the cries used in the present study represented a range of preterm and full-term infants' cries, the sample of stimuli was undoubtedly not entirely representative of full-term and preterm infants cries. Cries were collected under the stress of a neurological exam, they were listened to in the absence of the cryers through a cassette recorder, and they were rated by women who were not at the time responsible for the care of the cryers or other young infants. The perceived qualities of preterm cries and their contribution to optimal infant caregiver relationships needs to be conceptualized and studied in a framework which takes into account a panorama of infant behaviors (e.g., Brazelton, 1973). Features of the naturalistic caregiving environment (Lester & Zeskind, 1979) that promote or hinder healthy development will ultimately need to be investigated if we are to understand fully the interplay of infant affect and stress with adaptive and maladaptive parent-child interaction. REFERENCES Barnett, C. R., Leidarman, P. H., Grobstein, R., & Klaus, M. H. Neonatal separation: The maternal side of interactional deprivation. Pediatrics, 1970, 45, 197-205. Bell, R. Q. Parent, child, and reciprocal influences. American Psychologist, 1979, 34, 821-826. Bowlby, J. Attachment and loss (Vol. 1). New York: Basic Books, 1969. Brazelton, T. B. Neonatal behavior assessment scale. Philadelphia: J. B. Lippincott, 1973.
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