Infant stimulation of maternal instruction

INFANT BEHAVIOR AND DEVELOPMENT 1,205-215 (1978)

Infant Stimulation of Maternal I nstruction*

M E R E D I T H J. WEST AND H A R R I E T L. R H E I N G O L D

University o f North Carolina at Chapel Hill

This study investigated the extent to which the speech of mothers was stimulated and modified by their year-old infants' behavior. Of the 2502 utterances of 15 mothers, recorded in a 15-rain session in the laboratory, 70% occurred within 2 see of six preselected exploratory and social behaviors of the infants. Furthermore, the mothers used different categories of speech in response to the different behaviors. Inspection also showed that their speech provided the infants considerable information about the envirofiment. In summary, the mothers' speech was not only adjusted to the varying activities of their infants but by its informative nature provided the infants useful connections between act and words.

This study had two purposes: to assess the extent to which the speech o f mothers was stimulated and modified by the nature o f their infants' behavior, and to document the informative nature o f their speech. The study qualifies as an example of the interaction between infant and mother: it explores the effect o f the infant's behavior on the m o t h e r ' s verbal behavior, examines the relationship between what the infant does and what she says, and then weighs the contribution o f what she says to the infant's store o f knowledge. In these ways the study demonstrates how b o t h infant and m o t h e r contribute to the interaction. Much study has been devoted to charting the syntactical properties o f mothers' speech to their infants (e.g., Nelson, 1973; Phillips, 1973). Some attention has been paid to the topics o f discourse used b y mothers (Nelson, 1973), and some to the role o f the infants' nonverbal behaviors in stimulating the speech addressed to them (Cohen & Beckwith, 1976; Collis & Schaffer, 1975). In no study, however, has the relation between the mother's speech and her infant's behavior been the major focus o f investigation. *Parts of this paper were presented at the biennial meeting of the Society for Research in Child Development, New Orleans, March 1977. The investigation was supported by research grants HD01107 and HD23620 from the National Institute of Child Health and Human Development to H.L.R., and grant number MR001 from the Spencer Foundation to M.J.W. Requests for reprints should be sent to Meredith J. West, Department of Psychology, Davie Hall 013A, University of North Carolina, Chapel Hill, NC 27514. 205

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The stimulus for the present study arose from observations that mothers, having been instructed to perform several tasks with their infants in the laboratory, chose on their own initiative to supplement their children's experiences by describing, often in rich detail, the properties of the new setting (Hay, 1976). Subsequent observation in the field lent support to these laboratory findings; furthermore, it suggested the possibility that the mothers' speech was sensitive to the activities of their infants. To gain further information on the nature of the mothers' verbal responses to the stimuli that their infants provided, we placed both infant and mother in a relatively unstructured situation in the laboratory with no special constraints on their behavior. Attention was paid to certain preselected behaviors of the infants and primarily to the mothers' verbal responses.

METHOD

Subiects Fifteen mother-infant pairs served as subjects. The pairs were selected by availability from records of the North Carolina Memorial Hospital and the Durham County Register of Deeds. The mean age of the 8 male and 7 female children was 12.2 months (range, 11.6-12.7). The mothers' ages ranged from 23 to 35 with a mean of 28.5 years, and their years of education ranged from 12 to 20 with a mean of 15 years. The records of 2 pairs were not used: in one, the mother's speech was inaudible; in the other, the infant fussed during the trial.

Procedure Mothers were told by telephone that we wished to study the behavior of infants and their mothers in a new setting; 93% agreed to participate. Taxi service was provided. In the laboratory the mothers were instructed to behave as they naturally would when taking their infants to a new place. They were told they could follow the infants as they moved through the rooms, talk to and play with them, or sit and watch. In a word, they were to behave ih any way that seemed natural and comfortable. The mother then carried her child into the experimental suite where the cameras, microphones, and one-way windows were pointed out. The trial began when the experimenter left, and lasted 15 minutes.

Experimental Environment Three adjoining rooms, one large room (2.9 x 4.2 m) and two smaller rooms (2.4 x 3.6 m), comprised the experimental environment. The large room contained a chair for the mother centered along the back wall and facing the smaller

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rooms, two colorful posters, and a mobile of birds. Two plastic fruits were on the chair. Each small room contained a cushion and" two toys; in one room, a small cow (Creative Playthings) and a roly-poly chime ball (Fisher-Price), and in the other, a "Snoopy" pull toy (Fisher-Price) and a pyramid of plastic tings (Fisher-Price). The behaviors of mother and child were observed through one-way windows at the rear of the toy rooms and were also recorded by closed-circuit TV cameras, one fixed and the other remotely controlled to track their activities. In addition, microphones transmitted their vocalizations to audiotape. Measure of Infants'Behavior

The behaviors were defined as follows: l o o k s a t o b j e c t - the infant stops an activity to orient his head and eyes toward an o b j e c t ; f i r s t c o n t a c t s - the infant contacts an object for the f i r s t time with feet or hands while looking at the object; m a n i p u l a t e s - the infant moves an object with feet or hands while looking at the object; s h o w s - t h e infant directs the mother's attention toward an object by p o i n t i n g , that is, extending an arm or index finger toward an object, or by h o l d i n g o u t or u p an object; gives - the infant releases an object into the hand or lap of the mother; vocalizes - t h e infant emits a discrete voiced sound, (a) with no accompanying behavior, or (b) while displaying one of the preceding behaviors. Looks at, first contacts, and manipulates were considered to be exploratory behaviors; shows, gives, and vocalizes, social behaviors. Measures of Mothers' Speech

The transcriptions of the mothers' speech were divided into utterances by pauses longer than two seconds, the completion of an intonational pattern, or a change in the topic of conversation. Four main categories of speech, established from the utterances themselves, together with a fifth catch-all category, labeled i n c i d e n t a l speech, were sufficient to include all the utterances. The categories were defined as follows: n a m e s o r d e s c r i b e s - names objects ("It's a pretend apple"; "That's a camera") or describes their properties ("That's like your toy at home"; "The cushion is soft"); q u e s t i o n s o r verbalizes i n f a n t ' s a c t i v i t y questions or verbalizes what the infant sees ("What are you looking at?"; "You're looking at the cow") or knows ("Do you know what that is?", "You know the name of that") about the environment, or describes the infant's activity ("Y~u put the cow on the chair"), state ("You're tired"), or opinion ("You like that toy"):, d i r e c t s t h e i n f a n t ' s a c t i v i t y - directs the child to do something by an imperative ("Bring me the ball") or by a question ("Can you pull the puppy dog?"); a c k n o w l e d g e s o r praises t h e i n f a n t - comments on the infant's activity with such words as "Thank you," "Yeah," "That's a good girl"; i n c i d e n t a l speech - describes own activity ("I'm going in here") or utters nonverbal sounds ("Hm," "Huh") or unintelligible phrases.

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After all the mothers' utterances were categorized, the infant behaviors and the utterances were matched; that is, an utterance was judged t o be a response to an infant behavior if it began after the onset, or within two seconds of the offset, of one of the six infant behaviors. More than one utterance could occur within this period of time.

The Observers and Their Agreement The infants' behaviors were independently recorded by two observers behind the one-way windows for nine of the children; for the remaining six, the measures were recorded, also independently, from videotape by a second pair. The infants' vocalizations, and whether they accompanied one of the other behaviors, were recorded from videotape by the first pair of observers. The mothers' speech was transcribed by one observer and reviewed by a second. The speech was then independently coded into the five categories by a third pair of observers. Observer agreement was calculated by comparing the total frequency recorded by one observer with that of the second; the smaller sum was then divided by the larger. The median percentages for the infant behaviors were as follows: 83% for looks at (range, 57-98); 100% for first contacts (range, 86-100); 90% for manipulates (range, 70-100); 80% for shows (range, 33-100; however, the mean difference between the observers was only 0.3 shows); 100% for gives (range, 86-100); 93% for vocalizes alone (range, 81-95); and 87% for vocalizations accompanied by one of the other behaviors (range, 76-93). The median percentage of agreement for matching the mothers' speech in response to the infants' behavior was 86% (range, 77-93). The median percentage of agreement for categorizing the mothers' speech was 100% (range, 95-100). Only those behaviors agreed on by the two observers were used for data analysis.

Data Analysis For each behavior, the mean proportion of infant behaviors that each mother responded to with each of the five speech categories was calculated. Proportions were used to equate for differences among mothers in (a) the number of opportunities each had to respond to a given behavior and (b) the number of infant behaviors responded to by each. This procedure can result in proportional scores that sum to more than 1.00 because the mothers often produced more than one utterance to an infant behavior. RESULTS The infants provided their mothers considerable opportunity to respond (Table 1). Of the 2502 utterances recorded for the mothers, 1752 or 70% occurred within two seconds of the infant behaviors selected for study. Of this

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TABLE 1 Mean Frequency of Infants' Behaviors and Mean Percentage of Mothers' Responses

Infants' behaviors

Mean number

Exploratory Looks at First contacts Manipulates

39.2 6.5 29.9 10.0a 6.0 b 43.0

Social Shows Gives Vocalizes only Vocalizes with another behavior

42.4

Mean % of mothers' responses

Range

14-64 3-10 15-57

56.1 47.2 59.8

29- 79 0 - 90 33- 87

2-20 1-16 10-87

70.5 93.3 23.5

38-100 67-100 7 - 72

4-81

73.3

50-100

Range

aMean number for the 11 infants displaying the behavior. bMean number for the 10 infants displaying the behavior.

total, 80% were responses to the exploratory behaviors of looks at, first contacts, and manipulates, and the remaining 20% to the social behaviors of shows, gives, and vocalizes with no accompanying behavior. The mothers also said more to each of the exploratory behaviors, averaging 2.1 utterances in response to an exploratory behavior, in contrast to 1.1 to a social behavior. Although the mothers said less to the social behaviors, they responded to more of them, responding most often when the infants showed or gave them objects. They also responded more frequently when the infants' vocalizations accompanied one of the five behaviors than when they did not (Table 1).

Sex differences. The frequency of the mothers' speech to male and female infants did not differ: The mothers spoke an average of 175.0 utterances to males (range, 116-252) and 172.1 utterances to females (range, 89-251). Likewise, the number of infant behaviors the mothers responded to was similar for both sexes: The mothers responded to 61.4% of the male infants' behaviors (range, 38.1-78.1) and to 65.4% of the females' (range, 43.1-83.1); the difference was not reliable by test. Categories of Mothers' Verbal Responses To determine if the mothers used different categories of speech to the different infant behaviors, the mean proportions of speech in each category were first compared for the general classes of exploratory and social behavior. By inspection the results showed that the mothers used more names and descriptions, more

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questions and verbalizations, and more directives to the three e x p l o r a t o r y behaviors, and more acknowledgments and praise to the social behaviors. Incidental speech did not differ "appreciably for the two categories. Thus, the mothers' speech differed by the general nature o f their children'sactivities: they supplied the most information about the environment when their children were actively investigating it, and they showed recognition o f their infants' social behaviors by acknowledging that they had seen or heard or approved o f their infants' actions. For each o f the individual behaviors, differences in the categories also appeared (Table 2). When the infants looked at an object, the mothers most often questioned or verbalized the infants' activity (e.g., "What are you looking at?"; " Y o u are looking at the cow."). When the infants first touched an object, the mothers most frequently named or described it ("That's the dog's tail."). When the infants manipulated an object, the mothers named or described it about as frequently as they questioned or verbalized what the infants were doing with it. When the infants showed the mother an object, the mothers most often named

TABLE 2 Mean Proportions of Mothers' Speech Categories in Response to Infants" Behaviorsa

Categories of mothers' speech Infants' behaviors

Names or describes environment

Questions or verbalizes activities

Directs

Acknowledges or praises

Incidental

Exploratory Looks at First contacts Manipulates

.35 .47 .42

.54 .37 .44

.21 .05 .22

.09 .12 .22

.20 .15 .31

Social Shows Gives Vocalizes only

.48 .21 .14

.21 .14 .24

.15 .05 .08

.23 .64 .13

.20 .09 .41

.26

.54

.21

.08

.31

.40

.54

.25

.29

.49

.59

.20

.05

.31

.I 1

Vocalizes with behaviors b Vocalizes and looks at Vocalizes and manipulates Vocalizes and shows

aNote. The proportions sum to more than 1.00; see text. bThese behaviors represent subsets of some of the exploratory and social behaviors; first contacts and gives occurred too infrequently to calculate accompanying vocalizations.

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or described it. When the infants gave their mothers an object, the mothers most frequently responded by acknowledging the giving'or by praising the infant. Of all the speech categories, directives were the least frequent (Table 2). When, however, the mothers did direct their infants, it typically was in response to the infant's manipulating an object or looking at something (e.g., "Can you give it to me?"). The effect of vocalizations accompanying a behavior, a subset of all instances of that behavior, showed that the mothers used more incidental speech, primarily nonverbal sounds, and fewer names and descriptions to the looks accompanied by vocalizations than to those occurring without vocalizations. Likewise, when the infants vocalized while manipulating an object, the mothers more frequently questioned or verbalized their infants' action and increased their use of incidental speech. When infants showed and vocalized, the mothers more often named and described the object and acknowledged or praised their infant's activity. When, however, the infants did no more than vocalize, the mothers responded primarily with incidental speech. Thus, the mothers responded differently to the same behaviors when they were accompanied by vocalizations. The different behaviors of the infants also affected how much speech and how many categories the mothers used. The mothers said the most when the infants manipulated objects (2.8 utterances) and the least when their infants only vocalized (1.1 utterances). The number of categories differed similarly: The mothers used the most categories when their infants manipulated objects (1.6) and the least when their infants only vocalized (1.0). When the behaviors were accompanied by vocalizations, again manipulation evoked the most speech (3.2 utterances) and the most categories (2.0 categories). Thus, what the infants were doing influenced not only what but how much the mothers said. The data discussed thus far refer to the 70% of the mothers' speech coded as responses to infant behaviors. What characterized the 30% of the mothers' speech not yet accounted for? Eighteen percent fell into the category of names or describes the objects in the environment; 33%, of questions or verbalizes the infants' activities; 16%, of directs their activities; 9%, of acknowledges their behavior or praises them; and 25%, of incidental speech. The comparable distribution by categories for the 70% of speech responding to the infants' behaviors were 25, 31, 14, 13, and 17%, respectively. The similarities may well have resulted from the conservative procedure of counting as responses only those utterances occurring within 2 sec of the offset of a behavior; therefore, some larger proportion of the mothers' speech than thus accounted for might in fact have qualified as responses to the infants' behavior. Alternatively, the mothers' speech may have occurred in response to some instances of the selected behaviors that were not observed or to behaviors other than those selected for study. Of consequence, however, is the finding that 70% of their speech did occur in almost immediate response to the selected infants' behaviors and that the categories of responses appeared to differ by the behaviors.

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Comparison of individual and group proportions. As further support for the effects of the infants' behaviors on the mothers' speech, the distribution of speech categories for each mother was compared with those obtained for the sample as a whole. Substantial agreement was found between the individual and group scores for each behavior; for example, agreement ranged from 62 (for the behavior of showing) to 87% (for giving and looking at) for the category of speech used most frequently, and from 63 (for showing) to 90% (for giving) for the category of speech used least frequently. The Informative Nature of Mothers'Speech The mothers named not only the toys, the mobile, and the pictures on posters, but many less prominent objects in the rooms, such as the cameras, cushions, microphones, tape markers on the floor, covered electric outlets, the chair, the door sill, and even the floor. They also named small details of the toys such as the eyes, ears, and tail of the dog, as well as the shoe tied around its neck. The mothers also described the colors of the objects, their texture ("It's not as soft as your pillow"), their response properties ("If you touch them, they fly."; "If you wiggle it, it moves."), and their familiarity or novelty ("That's a ring toy like Kate's."; "I don't think you've ever seen a cow before."). The plastic fruits occasioned many comments about their make-believe qualities ("That's not a real banana."; "It's a plastic apple, Mommy can't peel it for you."). Likewise, the mothers gave details about the toy animals, clarifying the cow's gender ("It's really a bull.") and imitating animals' sounds and movements, sometimes even correcting their own rendition ("Cows don't sound exactly like that."). They made the animals real for the infants by having the cow "speak" to the infants or by asking the children to take the dog for a walk. The mothers also provided information in other ways. For example, they solicited information from their infants ("What's a cow say? You learned it the other day.") and corrected their children's attempts at names ("It's a cow, not a 'nana.'"). Even the infrequent directives were often of a tutorial nature: The mothers told the infants what to do with a toy, saying, "Put the yellow one on now," often while demonstrating the act. Many of the other directives were requests for the infant to bring something to the mother, thus allowing the mother to test her infant's knowledge of the identity of-the object she had named. The mothers also gave the appropriate verbal response for a gift, and responded to the infants' vocalizations with sounds like "Uh huh" or "Hm," as if they were conversing with one another. In many ways, then, the mothers provided their children with a wealth of information about the environment, modeled appropriate verbal responses, and acknowledged their children's attempts at conversation.

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Mothers 'Nonverbal Responses Although the mothers' speech was the primary focus of study, the mothers also responded to the infants' behaviors nonverbally. Many mothers demonstrated the movements, as well as the sounds, of the toy animals: They made the cow or dog "walk" toward the infants or they blew on the birds in the mobile to make them "fly." Many mothers also pretended to bite into the plastic apple or banana and several even demonstrated how to peel the banana. In addition, the mothers often assisted their infants' attempts to manipulate the stacking rings: The mothers held the rings over the stacking pole and then allowed their infants to complete the action or guided their infants' hands as the infants tried to place the rings. Thus, not only was the mothers' speech geared to instruct their infants; many of their actions reflected this aim as well.

General Properties of Mothers' Speech The mean number of words in the utterances was 4.06 (range, 2.97-6.85). Questions accounted for 31% of all speech, imperatives for 11%, and declarative statements or single word utterances for 43%. Only 10% o f th e utterances were exact repetitions, that is, the mother repeated her statement verbatim. With the occasional exception of a mother's imitating her child's attempt to name an object (e.g., "nana" for "banana" or "ap" for "apple"), baby talk (e.g., "birdie") was a rare occurrence.

DISCUSSION The results show that the speech of the mothers was closely related to what their year-old infants were doing. The mothers did not just speak but adjusted what they said to the ongoing activities of their children. That there was such synchrony between the mothers' speech and the infants' behaviors attests to the mothers' sensitivity to their children. The greater anaount of the mothers' responsiveness to the infants' social behaviors seems reasonable given that these behaviors were directed toward them. The considerable amount of responsiveness to the infants' exploratory behaviors shows how attentive these mothers were to even so relatively inconspicuous an observation as the direction of their infants' gaze. Not only did the mothers respond differently to the different behaviors but the nature of their responses were judged to be appropriate to the behaviors. When the infants looked at objects, the mothers typically questioned or verbalized the target of the infant's gaze. When the infants showed an object or first

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touched one, the mothers typically supplied its name. In contrast, the infants' manipulation of objects, a more complex set of activities than the other behaviors, evoked a more varied response. The informative nature of the mothers' speech con.stitutes the second main finding. The mothers labeled the objects in the environment and elaborated on their properties. They put into words what the infants were doing or what they could do. They spoke the proper phrases for gifts, and they responded, even if only with "Hm"s, to their infants' vocalizations. They were teachers par excellence. The infants in turn provided the mothers ample opportunities for instruction. They were active and inquisitive in their new surroundings. The mothers' statements themselves document the scrutiny with which the infants examined the laboratory environment. The mothers talked not only about the toys but also about such minor details as the cracks between the vinyl squares of the floor and its cleanliness, details brought to their attention by the exploratory activities of their infants. Some characteristics of the study qualify the results. First, the relatively superior educational level of the mothers may have contributed not only to their sensitivity to their infants' behavior but also to the informative nature of their speech. Second, the brief period in a laboratory, with no other assigned activity but to behave as they normally would, undoubtedly increased the amount of attention they paid their infants. Such a condition, however, could contribute only to the frequency and richness of their speech, not to their responsiveness to the cues the infants provided or the distinctions they made in responding to these cues. Finally, in the absence of a suitable statistic for testing these distinctions, the results are based on inspection alone. The data of this study, in summary, add a new dimension to knowledge about the speech of mothers to their infants. Such speech is often short, simple, and concrete (Nelson, 1973; Phillips, 1973), but above all it is exquisitely attuned in its sensitivity and relevance to the infant's behavior. Furthermore, what the mothers said not only supplied information but provided the infants a potentially meaningful contingency between acts and words. ACKNOWLEDGMENTS We thank Mary Ann Emmons, Sara P. Sparrow, and Heinz J. Whitefoot for valued help in collecting and analyzing the data. REFERENCES Cohen, S. E., & Beckwith, L. Maternal language in infancy. Developmental Psychology, 1976, 12, 371-372. Collis, G. M., & Schaffer, H. R. Synchronization of visual attention in mother-infant pairs. Journal of Child Psychology and Psychiatry, 1975, 16, 315-320.

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Hay, D. F. Following their companions as a form of exploration for human infants. Unpublished doctoral dissertation, University of North Carolina, 1976. Nelson, K. Structure and strategy in learning to talk. Mdnographs of the Society for Research in Child Development, 1973, 38(1-2, Serial No. 149). Phillips, J. R. Syntax and vocabulary of mothers' speech to young children: Age and sex comparisons. Child Development, 1973, 44, 182-185.