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A simplified method for measuring infant temperament
188
August, 1970 The Journal o/ P E D I A T R I C S
A simplified methodfor measuring infant temperament A questionnaire has been developed [or assessing temperamental characteristics o[ babies in the 4 to 8 month range and has been initially standardized on 101 babies in a single private practice. It is based directly on the research interview technique o[ Thomas and associates t and yields similar results, but it can be completed by the mother in about 20 minutes and scored in less than 10. Its principal value is in determining the presence o[ the characteristics o[ the dificult baby syndrome, which may be inadequately differentiated in the mother's general description. There are other possible applications in practice, teaching, and research.
William B. Carey, M.D. MEDIA, PA.
T t~ E ~ E I s considerable evidence to support the view that all babies are not alike, physiologically or psychologically, at birth. The observant pediatrician soon learns that general rules of infant care cannot be applied with equal ease and efficacy to all infants. When psychologic problems arise in the infant, he must make some determination of the infant's own behavioral style, or temperament, in addition to the contributions of the environment. Some complicated techniques have been evolved for research on temperamental differences, the most prominent being that designed by Thomas and associates? However, no method Suitable for pediatric practice has yet been developed and published. This report describes an attempt to fill From the Children's Hospital o~ Philadelphia. Presented in part at Annual Meeting of The American Academy o[ Pediatrics, Chicago, Oct. 19, 1969. Address ]or reprints: 319 W. Front Street, Med~a, Pa. Vol. 77, No. 2, pp. 188-194
that need by the preliminary design and standardization of a questionnaire ~ that can be completed~easily and reliably by the mother and scored quickly by the doctor or his secretary. This paper also presents some findings of the application of this questionnaire to research. T h e New York Longitudinal Study (NYLS) of Thomas and associates 1, 2 was started in 1956 with the basic view that individual differences, or primary reactive patterns, are "an independent major variable which, while interacting with environmental forces in personality development, has an existence and continuity of its own. ''~ The 136 children were studied by various methods, but primarily by parent interviews" done periodically, starting at about 3 months. The authors found that the results of their in"For Questionnaire, order Document No. NAPS-01044 from ASIS National Auxiliary Publications Service, c/o CCM Information Sciences, lnc., 909 3rd. Ave., New York, N. Y. 10022. Remit $2.00 for each microfiche or $5.00 for each photocopy.
Volume 77 Number 2
Method [or measuring in[ant temperament
terviews correlated highly with direct observations made of the children. The data sought were descriptions of the children's behavior, especially how they behaved in specific situations. The interview summaries were then scored by specially trained raters, who assigned values on a 3 point scale for each of the 9 categories of reactivity (activity, rhythmicity, approach-withdrawal, adaptability, intensity, threshold, mood, distractibility, and persistence). T h e total points for the 3 levels in each category were converted by a weighting process to a single score between 0 and 2; this was used to arrive at a diagnostic label for each category, such as regular or irregular, and adaptable or nonadaptable. Vari6us diagnostic clusters of these characteristics emerged: the difficult baby, the slow-to-warm-up baby, the easy baby, etc. The difficult baby was irregular, unadaptable, low in initial approach, intense, and predominantly negative; the easy baby had the opposite characteristics. Several problems arise in attempts at practical application of this technique by others. (1) The interview and dictation of the summary take an hour and a half or more, an amount of time not readily available to the practicing pediatrician. (2) The scoring process, which takes about half an hour, is tedious, open to various interpretations, and is done with complete authority only by one of the NYLS raters. (3) The published descriptions of the interview technique do not specify what standards are used to convert the weighted score in each category into a diagnostic label. By personal communication, however, I have learned that the standard is the mean, which varies with the age and category. 4 (4) Even a careful reading of the NYLS publications gives one the impression that all babies can rather easily be fitted into one or another of the diagnostic clusters of difficult, easy, slow-to-warm-up, etc. Yet, there are many babies who cannot be so easily designated. For example, the baby who is highly irregular but otherwise easy cannot be regarded as being completely easy or difficult. Thus, while the research
1 89
technique of Thomas and associates is an ingenious addition to our approach to the study of temperament, it needs some clarifications and adaptations to make it appropriate for pediatric use. SUBJECTS AND METHODS
The 101 subjects used to standardize this questionnaire were almost all of the babies between about 4 and 8 months of age seen in my private practice during the course of one year. Seven babies were excluded because their mothers were not their full-time caretakers and one because of the mother's poor grasp of English. Of the 103 questionnaires given or sent, all were completed and returned except for two that were allegedly lost by the post office. This was a generally middle-class sample; 55 per cent of the fathers and 41 per cent of the mothers were college graduates. Fortythree infants were the firstborn of the mother while 58 were later born. By chance 66 were males and only 35 females. The questionnaire was based directly on the description of the interview of Thomas and associates in their book, Behavioral individuality in early childhood. 1 From this material it was possible to set up 70 statements, each with 3 choices for completion, describing specific behavior of the baby in certain situations. For example, item 18: (a) when full, baby clamps mouth closed, spits out food or milk, bats at spoon, etc. (intense); (b) variable; (c) just turns head away or lets food drool out of mouth (mild). As in the interview, the infant's actual responses were asked about and not maternal reactions and interpretations. A letter accompanied the questionnaire asking the mother to circle the "a, .... b," or "c" before the choice that properly described her baby. If none of the possibilities was truly suitable, no response was to be given. It was also stressed that there were no good and bad or rigl{t and wrong answers, only descriptions of what the baby did. From the 70 items 76 ratings were obtained in the nine categories of reactivity. (Six items gave points in two categories.)
190
Carey
The total ratings at the 3 levels in each category were then multiplied by 0, 1, and 2; e.g., the total of intense ratings was multiplied by 0, variable by 1, and mild by 2. These products were added and that sum divided by the total number of completed items in the category. This yielded a mean score between 0 and 2, representing the infant's typical reaction for that category. Each baby received 9 such average reactivity scores.
In addition, each mother was asked to describe briefly her general impression of her infant's temperament and to indicate in what way it had been a problem. The mothers were also requested to give an over-all rating of their babies in each of the 9 categories, such as (1) generally intense, (2) variable, (3) generally mild. Finally, data were solicited on age and educational level of the parents, previous experience with babies, and illness during the pregnancy and in the baby. The questionnaires were administered when the babies were 3 ~ to 8 ~ months of age, or the equivalent in the prematurely born, with 2 exceptions. The mothers were asked to tell how long it took them to complete the temperament part of the questionnaire. The average was 21.5 minutes. The range was 6 to 60 minutes, the vast majority taking between 15 and 25 minutes. A scoring sheet was set up so that the questionnaire could be rated quickly. The usual time for this procedure was 8 to 10 minutes. In the initial phase of this project an attempt was made to compare the results of the questionnaire with the original NYLS interview by asking the same mothers to complete both. Four mothers were interviewed by a pediatrician familiar with the NYLS technique (Dr. Thomas Coleman), and immediately afterward they were asked to fill out the questionnaire. The interview summaries were scored by NYIfS raters. To estimate the reliability ot the instrument these mothers unexpectedly received the questionnaire for a second time 2 weeks
The Journal of Pediatrics August 1970
later. This seemed long enough for them to have forgotten most of what they had written before but not long enough for the babies to have changed significantIy. RESULTS
The results of the 101 questionnaires should be looked at first in comparison with the interview technique, then as contrasted with the mothers' general impressions of their babies. The means and standard deviations for the 9 categories of reactivity were computed and are shown in Table I with the comparable NYLS values. On the basis of the numerical score alone (i.e., using 1 as the midpoint), one can conclude that by both techniques the average baby at 4 to 8 months is active, regular, adaptable, high in initial approach, low in threshold, mild, predominantly positive in mood, distractable, and persistent. The questionnaire means are almost all closer to 0 than those of the interview, but this fact, to be discussed later, appears to be of no practical importance since babies rated by each technique are judged by the mean values for that same technique and not by the other. Another way to compare the two techniques is to look at the frequency of the concurrent signs of the difficult child: irregularity, slow adaptability, initial withdrawal, intensity, and negative mood. In other words, what incidence of components of difficult temperament was turned up in the Thomas Table I
Questionnaire
Activity Rhythmicity Adaptability Approach Threshold Intensity Mood Distractibility Persistence
0.52 0.53 0.35 0.48 1.08 1.05 0.40 0.57 0.69
+ 0.32 + 0.46 +- 0.26 + 0.35 i 0.39 + 0.32 + 0.25 + 0.32 ~ 0.38
NYLS interview (Period I: mean age 5.9 months)*
0.80 0.56 0.50 0.67 1.20
1.21 0.83 0.59 0.40
Volume 77 Number 2
Method for measuring infant temperament
series by their interviews and how much in this series by the questionnaire? Using their figures for babies at 1 year, 4 since those at 6 months are not available, we find a close resemblance. The frequencies of babies with 5 of these characteristics simultaneously are 10% by the interview and 8% by the questionnaire; for 4 there are 17 per cent and I5 per cent; for 3, 20 and 23 per cent; for 2, 27 and 22 per cent; and for 0 to 1, 26 and 31 per cent. If use of the two methods identifies about the same percentage of difficult temperament in different but similar populations, the next question is do they also yield similar results from the same babies? For 3 of the 4 babies who were examined both by interview and questionnaire at about the same time, there was, with one exception, complete agreement as to the rating above or below the mean for the 5 major categories. In the test of reliability there was agreement without exception in the 5 major categories for these three who were all between 6 and 7 months of age. The fourth baby was under 3I~ months; his results were discarded. There is a limitation to diagnosing a baby as being difficult simply because all 5 of the scores of the major categories are on the difficult side of the means. By this method no allowance is made for whether the infant is only slightly or very negative, irregular, etc. For this reason it seemed logical, and made sense clinically, to redefine the difficult baby as one having 4 or 5 difficult category ratings, 2 or more of which were greater than one standard deviation from the mean. With this redefinition the group of 8 difficult babies loses 3 but adds 6 others. The easy baby was defined as having 0 to 2 such ratings, but none as large as one standard deviation. Intermediate babies, high and low, fell in between. (Intermediate high h a d 4 to 5 difficult ratings with 1 > 1 S.D. or 2 to 3 with 2 to 3 > 1 S.D. Intermediate low had 3 to 5 with 0 > 1 S.D. or 1 to 3 with 1 > 1 S.D.) The 101 babies could then be divided into 11 difficult, 49 intermediate (I5 high and 34 low), and 41 easy.
19 1
The difficult babies were not found significantly more often among either sex (11 per cent from b o t h ) ; brain injury was not evident in any of them. The only unusual feature in the obstetric and newborn histories was that 4 of the 11 were delivered by cesarean section (3 initial and 1 repeat), but all were in good condition at birth. There were slightly more among the firstborn infants (16 per cent) than the later born infants (7 per cent), but the difference is not statistically significant. Similarly, the easy babies are found in approximately equal number in the 2 sexes (39 per cent male and 43 per cent female) and among the firstborn and later born infants (37 and 43 per cent). We now turn from the standardization of the questionnaire and the comparison of it with the interview to look at the differences between the mothers' general impressions of their babies and their own detailed descriptions of them as rated by the questionnaire. As one would expect, the more difficult the baby by questionnaire rating, the more likely the mother was to report having found his temperament a problem. Seventy-three per cent of the mothers of the difficult babies complained, 42 per cent of the intermediate high, 30 per cent of the intermediate low, and 13 per cent of the easy. T h e 3 who did not offer complaints about difficult babies had babies with scores on the lower end of the range and were primiparas who may not have known what to expect. With the easy babies, the unfavorable comments were mostly relatively trivial, such as high activity which made dressing and diapering difficult. A substantial number of mothers presented general impressions that markedly minimized the amount of difficulty their babies were giving them according to their questionnaire answers. In the over-all ratings of their babies in the 5 major categories, e.g., (1) generally intense, ( 2 ) v a r i a b l e , (3) generally mild, 18 mothers assigned their babies with ratings at the easy end of the scale, when by the questionnaire they had just indicated that they were greater than one standard
19 2
Carey
deviation on the difficult side of the mean (e.g., a mother said her infant was generally adaptable, when the questionnaire score indicated that he was very slow to adapt). The appearance of these discrepancies, which occurred in about one quarter of these judgments, bore no relationship to the mother's previous experience with babies, her educational level, a history of physical problems in the pregnancy or the baby, or whether the general impressions were given just before or after the questionnaire itself. The more difficult the baby, however, the more likely was the mother to make such errors in evaluation. Also, some categories were more subject to misinterpretation than others, from the highest in adaptability to none in intensity. An important factor in these distortions may have been the mothers' wishes to make their babies seem more socially desirable. Misinterpretations in the direction of difficulty were less common: Nine rated their infants as intense when the questionnaire indicated that they were mild, and one predominantly approaching baby was called the opposite. Finally, these data can be used to give some answers to certain intriguing questions about infants. Here are two: 1. Are there temperamental differences between the two sexes? There are differences of a few percentage points between males and females falling above the mean in the 9 categories of reactivity. None of these is statistically significant except in persistence. This group of males is evidently more persistent than the females (p < 0.01). It is not clear whether this is a maternal distortion, a statistical curiosity, or a valid observation on human nature. 2. Are Colicky babies temperamentally different from those who do not cry excessively? Using Wessel and associates '~ definition, 8 babies in this group were judged to be colicky. When their tell~peramental patterns were assessed weeks after the colic had stopped, 2 were difficult, 3 intermediate high, 3 intermediate low, and none were easy.
The Journal of Pediatrics August 1970
This study sample is small but the overrepresentation from the intermediate and difficult groups is significant (X2 = 4.1; p < 0.05). T h e fact that 9 of the 11 difficult babies were not colicky makes clear the point that the 2 groups overlap but are not identical. Furthermore, difficult temperament is not the only factor involved in the production of a colicky baby2 DISCUSSION
From the growing literature on individual differences, a few pertinent points should be made. Those investigations 7-9 of consistent differences in function of newborn infants have not yet shown that they endure or that they are important for later personality development. Escalona 1~ has made valuable contributions to our understanding of the interactions of infant and environmental variables but has measured only activity and excitability. While several commentators 3, 9, 11 have pointed out the importance of individual differences for the pediatrician, only Thomas and associates 1 have provided a technique that might be adapted for pediatric use. Chess a has stated that by 3 months these patterns have become fairly stable; the slightly later age of 3I~ to 4 months, or the equivalent in the premature infants, seems more accurate. As mentioned earlier, one baby had to be eliminated from the comparison study because at just over 3 months of age a quarter of the questionnaire items could not be completed. Another baby, rated as difficult at just under 5 months, was 8 weeks premature at birth. Three weeks later, when he was the equivalent of a 3 ~ - m o n t h old term baby, he became dramatically more easy, as confirmed b y a second questionnaire, and has remained so. Several other babies have seemed clinically to become much easier at around 3 89 months of age, part'icularly with a decrease in irregularity and fussiness. Many adjustment problems for mothers and babies occur before 3 ~ months, and although the questionnaire will measure the reactions of the baby at that time, it cannot be counted on to do it well or to predict
Volume 77 Number 2
Method for measuring infant temperament
future patterns reliably. The clinician should "be wary of prognostications regarding temperament during the first 3 ~ months. Thomas and associates 1 have analyzed the stability of these temperamental characteristics in the first 2 years of life and found some to be more consistent than others. In ahnost two thirds of the 9 categories, the average child's pattern was sustained through 5 different determinations during the first 2 years. The highest consistency was found in the 5 major categories used in the diagnostic cluster of the easy and the difficult babies: rhythmicity, adaptability, approach, intensity, and mood. Although they are fairly stable, temperamental characteristics, like many other psychologic phenomena, are apparently modifiable to some extent by experience. The questionnaire measures approximately the same behavior and yields about the same results as the NYLS interview. The differences in the results can be attributed to several possible causes. (1) Small variations occur in the material covered by the interview. (2) There are differences in scoring techniques. For example, the interview counts any crying in the infant as negative temperament even though it may be in response to painful trauma. (3) Some mothers may be more likely to choose 1 of the 3 questionnaire options repeatedly as a matter of habit. The considerable discrepancies between the mothers' over-all views of their babies and the actual questionnaire scores, particularly among the more difficult ones, should serve as a warning to the pediatrician not to accept too hastily any superficial impression of a baby's functioning. If he really wants to know what is going on with a baby, he must obtain descriptions of the baby, either by questionnaire or some sort of interview, and then make his own diagnosis. Clinical impressions are of value, however, in interpreting the questionnaire's results, since both it and the interview give equal scores to functions of differing import/race, such as irregularity of sleep and of bowel movements.
19 3
Only 5 of the 9 categories of reactivity are used in the determination of difficult, intermediate, and easy babies. Activity, distractibility, and persistence can be of significance in behavioral problems at a later date but are evidently not of major importance in early infancyY High or low threshold has not seemed to predispose to problems in behavior. In fact, 10 of the 15 very high threshold ratings were in easy babies. If these other 4 categories were eliminated from the questionnaire, it would take even less time to administer and rate without losing its principal value. What can be concluded about the usefulness of. this questionnaire in pediatric practice? 1. If there are no substantial problems in the mother's caring for the baby, the questionnaire could simply define the temperamental characteristics. This may be somewhat of a luxury, but some mothers have reported that just the thought required in answering the questions accurately was helpful in sharpening their perceptions of their babies' functioning. The mother of the one pair of twins in this study was helped to understand that the reason she felt more positively toward one of them was that his style of reacting made him easier for her to understand and respond to. 2. When there is a problem in the motherchild interaction, it is important to know what the contribution of the baby may be. As we have seen, the mother's general impression of the baby may be distorted. More thought must be given to determine the best way to use the questionnaire results in the clinical counseling situation. At present it seems wise to regard it as a screening device, which identifies difficult temperament but requires some additional interviewing to elaborate on these findings and their impact on the mother. 3. In pediatric residency training it is important to introduce the concept of temperamental differences. Having urged residents to consider this aspect of the child, we must provide them with some way to measure it.
194
Carey
4. Possible research applications are numerous: D o babies with certain temperamental characteristics such as persistence or activity achieve their developmental milestones earlier than others and seem to be brighter than they are? Are others besides the inactive babies 12 more susceptible to the effects of environmental deprivation? Is it quite certain that difficult babies function neurologically just the same as others? H o w does the clinician differentiate reliably between the minimally brain d a m a g e d and the difficult infant? Does the high rate of cesarean sections in this series indicate that obstetric complications, as well as genetic influences, 13 are a factor in the production of temperamental characteristics? There appears to be no simple answer to the p r o b l e m of how to live with a difficult baby. T h e parents of these babies, who seem to be no different from the general population, must be capable of unusual firmness, patience, consistency, and tolerance, lest a destructive interaction result in a lifelong behavioral disability. 2 For example, if the child is slow to adapt and gets upset in new situations, the parents may avoid these new situations for fear that the resulting turmoil will be harmful. His experience is limited narrowly and he becomes less confident of himself. T h e pediatrician can offer sedation for the baby when appropriate, assurance to the parents that they are not responsible by their actions for the baby's unpleasant behavior, and a fairly confident prediction that things will get better eventually if wisely managed. For example, he can counsel the parents of the unadaptable child not to let him back away from a reasonable exposure to new situations. Such babies do get easier to live with if well handled but are likely to show their difficulty later under stress or with new situations. 2 O n e mother of a very difficult baby, who is now a year old, recently re-
The Journal o] Pediatrics August 1970
ported at a routine visit that he has become relatively easy. A m o m e n t later she calmly added that the first week of their summer vacation had been a disaster because the baby had an extremely hard time adjusting to the unfamiliar place. The process of developing the questionnaire and evaluating its worth has been furthered considerably by the cooperation and support of two members of the NYLS team, Doctors Stella Chess and Sam Korn. REFERENCES
1. Thomas, A., Chess, S., Birch, H. G., Hertzlg, M. E., and Korn, S.: Behavioral individuality in early childhood, New York, 1963, New York University Press. 2. Thomas, A., Chess, S., and Birch, H. G.: Temperament and behavior disorders in children, New York, 1968, New York University Press. 3. Chess, S.: Individuality in children, its importance to the pediatrician, J. PEDIAT. 69: 676, 1966. 4. Korn, S.: Personal communication. 5. Wessel, M. A., Cobb, J. C., Jackson, E. B., Harris~ G. S., Jr., and Detwiler, A. C.: Paroxysmal fussing in infancy, sometimes called "colic," Pediatrics 14: 421, 1954. 6. Carey, W. B.: Maternal anxiety and infantile colic. Is there a relationship? Clln. Pediat. 7: 590, 1968. 7. Kron, R. E., Ipsen, J., and Goddard, K. E.: Consistent individual differences in the nutritive sucking behavior of the human newborn, Psychosom. Med. 30: 15I, 1968. 8. Bridget, W. H., and Relser, M., Psychophysiological studies of the neonate, Psychosore. Med. 21: 265, 1959. 9. Lipton, E. L., Steinschneider, A., and Richmond, J.: The autonomic nervous system in early life, New Eng. J. Med. 273: 147, 1965. 10. Escalona, S. K.: The roots of individuality, Chicago, 1968, Aldine Publishing Company. I1. Brazelton, T. B.: The early mother-infant adjustment, Pediatrics 32: 931, 1963. 12. Schaffer, H. R.: Activity level as a constitutional determinant of infantile reaction to deprivation, Child Develop. 37: 595, 1966. 13. Rutter, M., Korn, S., and Birch, H. G.: Genetic and environmental factors in the development of "primary reactive patterns," Brit. J. Soc. Clin. PsychoL 2: 161, 1963.
August, 1970 The Journal o/ P E D I A T R I C S
A simplified methodfor measuring infant temperament A questionnaire has been developed [or assessing temperamental characteristics o[ babies in the 4 to 8 month range and has been initially standardized on 101 babies in a single private practice. It is based directly on the research interview technique o[ Thomas and associates t and yields similar results, but it can be completed by the mother in about 20 minutes and scored in less than 10. Its principal value is in determining the presence o[ the characteristics o[ the dificult baby syndrome, which may be inadequately differentiated in the mother's general description. There are other possible applications in practice, teaching, and research.
William B. Carey, M.D. MEDIA, PA.
T t~ E ~ E I s considerable evidence to support the view that all babies are not alike, physiologically or psychologically, at birth. The observant pediatrician soon learns that general rules of infant care cannot be applied with equal ease and efficacy to all infants. When psychologic problems arise in the infant, he must make some determination of the infant's own behavioral style, or temperament, in addition to the contributions of the environment. Some complicated techniques have been evolved for research on temperamental differences, the most prominent being that designed by Thomas and associates? However, no method Suitable for pediatric practice has yet been developed and published. This report describes an attempt to fill From the Children's Hospital o~ Philadelphia. Presented in part at Annual Meeting of The American Academy o[ Pediatrics, Chicago, Oct. 19, 1969. Address ]or reprints: 319 W. Front Street, Med~a, Pa. Vol. 77, No. 2, pp. 188-194
that need by the preliminary design and standardization of a questionnaire ~ that can be completed~easily and reliably by the mother and scored quickly by the doctor or his secretary. This paper also presents some findings of the application of this questionnaire to research. T h e New York Longitudinal Study (NYLS) of Thomas and associates 1, 2 was started in 1956 with the basic view that individual differences, or primary reactive patterns, are "an independent major variable which, while interacting with environmental forces in personality development, has an existence and continuity of its own. ''~ The 136 children were studied by various methods, but primarily by parent interviews" done periodically, starting at about 3 months. The authors found that the results of their in"For Questionnaire, order Document No. NAPS-01044 from ASIS National Auxiliary Publications Service, c/o CCM Information Sciences, lnc., 909 3rd. Ave., New York, N. Y. 10022. Remit $2.00 for each microfiche or $5.00 for each photocopy.
Volume 77 Number 2
Method [or measuring in[ant temperament
terviews correlated highly with direct observations made of the children. The data sought were descriptions of the children's behavior, especially how they behaved in specific situations. The interview summaries were then scored by specially trained raters, who assigned values on a 3 point scale for each of the 9 categories of reactivity (activity, rhythmicity, approach-withdrawal, adaptability, intensity, threshold, mood, distractibility, and persistence). T h e total points for the 3 levels in each category were converted by a weighting process to a single score between 0 and 2; this was used to arrive at a diagnostic label for each category, such as regular or irregular, and adaptable or nonadaptable. Vari6us diagnostic clusters of these characteristics emerged: the difficult baby, the slow-to-warm-up baby, the easy baby, etc. The difficult baby was irregular, unadaptable, low in initial approach, intense, and predominantly negative; the easy baby had the opposite characteristics. Several problems arise in attempts at practical application of this technique by others. (1) The interview and dictation of the summary take an hour and a half or more, an amount of time not readily available to the practicing pediatrician. (2) The scoring process, which takes about half an hour, is tedious, open to various interpretations, and is done with complete authority only by one of the NYLS raters. (3) The published descriptions of the interview technique do not specify what standards are used to convert the weighted score in each category into a diagnostic label. By personal communication, however, I have learned that the standard is the mean, which varies with the age and category. 4 (4) Even a careful reading of the NYLS publications gives one the impression that all babies can rather easily be fitted into one or another of the diagnostic clusters of difficult, easy, slow-to-warm-up, etc. Yet, there are many babies who cannot be so easily designated. For example, the baby who is highly irregular but otherwise easy cannot be regarded as being completely easy or difficult. Thus, while the research
1 89
technique of Thomas and associates is an ingenious addition to our approach to the study of temperament, it needs some clarifications and adaptations to make it appropriate for pediatric use. SUBJECTS AND METHODS
The 101 subjects used to standardize this questionnaire were almost all of the babies between about 4 and 8 months of age seen in my private practice during the course of one year. Seven babies were excluded because their mothers were not their full-time caretakers and one because of the mother's poor grasp of English. Of the 103 questionnaires given or sent, all were completed and returned except for two that were allegedly lost by the post office. This was a generally middle-class sample; 55 per cent of the fathers and 41 per cent of the mothers were college graduates. Fortythree infants were the firstborn of the mother while 58 were later born. By chance 66 were males and only 35 females. The questionnaire was based directly on the description of the interview of Thomas and associates in their book, Behavioral individuality in early childhood. 1 From this material it was possible to set up 70 statements, each with 3 choices for completion, describing specific behavior of the baby in certain situations. For example, item 18: (a) when full, baby clamps mouth closed, spits out food or milk, bats at spoon, etc. (intense); (b) variable; (c) just turns head away or lets food drool out of mouth (mild). As in the interview, the infant's actual responses were asked about and not maternal reactions and interpretations. A letter accompanied the questionnaire asking the mother to circle the "a, .... b," or "c" before the choice that properly described her baby. If none of the possibilities was truly suitable, no response was to be given. It was also stressed that there were no good and bad or rigl{t and wrong answers, only descriptions of what the baby did. From the 70 items 76 ratings were obtained in the nine categories of reactivity. (Six items gave points in two categories.)
190
Carey
The total ratings at the 3 levels in each category were then multiplied by 0, 1, and 2; e.g., the total of intense ratings was multiplied by 0, variable by 1, and mild by 2. These products were added and that sum divided by the total number of completed items in the category. This yielded a mean score between 0 and 2, representing the infant's typical reaction for that category. Each baby received 9 such average reactivity scores.
In addition, each mother was asked to describe briefly her general impression of her infant's temperament and to indicate in what way it had been a problem. The mothers were also requested to give an over-all rating of their babies in each of the 9 categories, such as (1) generally intense, (2) variable, (3) generally mild. Finally, data were solicited on age and educational level of the parents, previous experience with babies, and illness during the pregnancy and in the baby. The questionnaires were administered when the babies were 3 ~ to 8 ~ months of age, or the equivalent in the prematurely born, with 2 exceptions. The mothers were asked to tell how long it took them to complete the temperament part of the questionnaire. The average was 21.5 minutes. The range was 6 to 60 minutes, the vast majority taking between 15 and 25 minutes. A scoring sheet was set up so that the questionnaire could be rated quickly. The usual time for this procedure was 8 to 10 minutes. In the initial phase of this project an attempt was made to compare the results of the questionnaire with the original NYLS interview by asking the same mothers to complete both. Four mothers were interviewed by a pediatrician familiar with the NYLS technique (Dr. Thomas Coleman), and immediately afterward they were asked to fill out the questionnaire. The interview summaries were scored by NYIfS raters. To estimate the reliability ot the instrument these mothers unexpectedly received the questionnaire for a second time 2 weeks
The Journal of Pediatrics August 1970
later. This seemed long enough for them to have forgotten most of what they had written before but not long enough for the babies to have changed significantIy. RESULTS
The results of the 101 questionnaires should be looked at first in comparison with the interview technique, then as contrasted with the mothers' general impressions of their babies. The means and standard deviations for the 9 categories of reactivity were computed and are shown in Table I with the comparable NYLS values. On the basis of the numerical score alone (i.e., using 1 as the midpoint), one can conclude that by both techniques the average baby at 4 to 8 months is active, regular, adaptable, high in initial approach, low in threshold, mild, predominantly positive in mood, distractable, and persistent. The questionnaire means are almost all closer to 0 than those of the interview, but this fact, to be discussed later, appears to be of no practical importance since babies rated by each technique are judged by the mean values for that same technique and not by the other. Another way to compare the two techniques is to look at the frequency of the concurrent signs of the difficult child: irregularity, slow adaptability, initial withdrawal, intensity, and negative mood. In other words, what incidence of components of difficult temperament was turned up in the Thomas Table I
Questionnaire
Activity Rhythmicity Adaptability Approach Threshold Intensity Mood Distractibility Persistence
0.52 0.53 0.35 0.48 1.08 1.05 0.40 0.57 0.69
+ 0.32 + 0.46 +- 0.26 + 0.35 i 0.39 + 0.32 + 0.25 + 0.32 ~ 0.38
NYLS interview (Period I: mean age 5.9 months)*
0.80 0.56 0.50 0.67 1.20
1.21 0.83 0.59 0.40
Volume 77 Number 2
Method for measuring infant temperament
series by their interviews and how much in this series by the questionnaire? Using their figures for babies at 1 year, 4 since those at 6 months are not available, we find a close resemblance. The frequencies of babies with 5 of these characteristics simultaneously are 10% by the interview and 8% by the questionnaire; for 4 there are 17 per cent and I5 per cent; for 3, 20 and 23 per cent; for 2, 27 and 22 per cent; and for 0 to 1, 26 and 31 per cent. If use of the two methods identifies about the same percentage of difficult temperament in different but similar populations, the next question is do they also yield similar results from the same babies? For 3 of the 4 babies who were examined both by interview and questionnaire at about the same time, there was, with one exception, complete agreement as to the rating above or below the mean for the 5 major categories. In the test of reliability there was agreement without exception in the 5 major categories for these three who were all between 6 and 7 months of age. The fourth baby was under 3I~ months; his results were discarded. There is a limitation to diagnosing a baby as being difficult simply because all 5 of the scores of the major categories are on the difficult side of the means. By this method no allowance is made for whether the infant is only slightly or very negative, irregular, etc. For this reason it seemed logical, and made sense clinically, to redefine the difficult baby as one having 4 or 5 difficult category ratings, 2 or more of which were greater than one standard deviation from the mean. With this redefinition the group of 8 difficult babies loses 3 but adds 6 others. The easy baby was defined as having 0 to 2 such ratings, but none as large as one standard deviation. Intermediate babies, high and low, fell in between. (Intermediate high h a d 4 to 5 difficult ratings with 1 > 1 S.D. or 2 to 3 with 2 to 3 > 1 S.D. Intermediate low had 3 to 5 with 0 > 1 S.D. or 1 to 3 with 1 > 1 S.D.) The 101 babies could then be divided into 11 difficult, 49 intermediate (I5 high and 34 low), and 41 easy.
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The difficult babies were not found significantly more often among either sex (11 per cent from b o t h ) ; brain injury was not evident in any of them. The only unusual feature in the obstetric and newborn histories was that 4 of the 11 were delivered by cesarean section (3 initial and 1 repeat), but all were in good condition at birth. There were slightly more among the firstborn infants (16 per cent) than the later born infants (7 per cent), but the difference is not statistically significant. Similarly, the easy babies are found in approximately equal number in the 2 sexes (39 per cent male and 43 per cent female) and among the firstborn and later born infants (37 and 43 per cent). We now turn from the standardization of the questionnaire and the comparison of it with the interview to look at the differences between the mothers' general impressions of their babies and their own detailed descriptions of them as rated by the questionnaire. As one would expect, the more difficult the baby by questionnaire rating, the more likely the mother was to report having found his temperament a problem. Seventy-three per cent of the mothers of the difficult babies complained, 42 per cent of the intermediate high, 30 per cent of the intermediate low, and 13 per cent of the easy. T h e 3 who did not offer complaints about difficult babies had babies with scores on the lower end of the range and were primiparas who may not have known what to expect. With the easy babies, the unfavorable comments were mostly relatively trivial, such as high activity which made dressing and diapering difficult. A substantial number of mothers presented general impressions that markedly minimized the amount of difficulty their babies were giving them according to their questionnaire answers. In the over-all ratings of their babies in the 5 major categories, e.g., (1) generally intense, ( 2 ) v a r i a b l e , (3) generally mild, 18 mothers assigned their babies with ratings at the easy end of the scale, when by the questionnaire they had just indicated that they were greater than one standard
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Carey
deviation on the difficult side of the mean (e.g., a mother said her infant was generally adaptable, when the questionnaire score indicated that he was very slow to adapt). The appearance of these discrepancies, which occurred in about one quarter of these judgments, bore no relationship to the mother's previous experience with babies, her educational level, a history of physical problems in the pregnancy or the baby, or whether the general impressions were given just before or after the questionnaire itself. The more difficult the baby, however, the more likely was the mother to make such errors in evaluation. Also, some categories were more subject to misinterpretation than others, from the highest in adaptability to none in intensity. An important factor in these distortions may have been the mothers' wishes to make their babies seem more socially desirable. Misinterpretations in the direction of difficulty were less common: Nine rated their infants as intense when the questionnaire indicated that they were mild, and one predominantly approaching baby was called the opposite. Finally, these data can be used to give some answers to certain intriguing questions about infants. Here are two: 1. Are there temperamental differences between the two sexes? There are differences of a few percentage points between males and females falling above the mean in the 9 categories of reactivity. None of these is statistically significant except in persistence. This group of males is evidently more persistent than the females (p < 0.01). It is not clear whether this is a maternal distortion, a statistical curiosity, or a valid observation on human nature. 2. Are Colicky babies temperamentally different from those who do not cry excessively? Using Wessel and associates '~ definition, 8 babies in this group were judged to be colicky. When their tell~peramental patterns were assessed weeks after the colic had stopped, 2 were difficult, 3 intermediate high, 3 intermediate low, and none were easy.
The Journal of Pediatrics August 1970
This study sample is small but the overrepresentation from the intermediate and difficult groups is significant (X2 = 4.1; p < 0.05). T h e fact that 9 of the 11 difficult babies were not colicky makes clear the point that the 2 groups overlap but are not identical. Furthermore, difficult temperament is not the only factor involved in the production of a colicky baby2 DISCUSSION
From the growing literature on individual differences, a few pertinent points should be made. Those investigations 7-9 of consistent differences in function of newborn infants have not yet shown that they endure or that they are important for later personality development. Escalona 1~ has made valuable contributions to our understanding of the interactions of infant and environmental variables but has measured only activity and excitability. While several commentators 3, 9, 11 have pointed out the importance of individual differences for the pediatrician, only Thomas and associates 1 have provided a technique that might be adapted for pediatric use. Chess a has stated that by 3 months these patterns have become fairly stable; the slightly later age of 3I~ to 4 months, or the equivalent in the premature infants, seems more accurate. As mentioned earlier, one baby had to be eliminated from the comparison study because at just over 3 months of age a quarter of the questionnaire items could not be completed. Another baby, rated as difficult at just under 5 months, was 8 weeks premature at birth. Three weeks later, when he was the equivalent of a 3 ~ - m o n t h old term baby, he became dramatically more easy, as confirmed b y a second questionnaire, and has remained so. Several other babies have seemed clinically to become much easier at around 3 89 months of age, part'icularly with a decrease in irregularity and fussiness. Many adjustment problems for mothers and babies occur before 3 ~ months, and although the questionnaire will measure the reactions of the baby at that time, it cannot be counted on to do it well or to predict
Volume 77 Number 2
Method for measuring infant temperament
future patterns reliably. The clinician should "be wary of prognostications regarding temperament during the first 3 ~ months. Thomas and associates 1 have analyzed the stability of these temperamental characteristics in the first 2 years of life and found some to be more consistent than others. In ahnost two thirds of the 9 categories, the average child's pattern was sustained through 5 different determinations during the first 2 years. The highest consistency was found in the 5 major categories used in the diagnostic cluster of the easy and the difficult babies: rhythmicity, adaptability, approach, intensity, and mood. Although they are fairly stable, temperamental characteristics, like many other psychologic phenomena, are apparently modifiable to some extent by experience. The questionnaire measures approximately the same behavior and yields about the same results as the NYLS interview. The differences in the results can be attributed to several possible causes. (1) Small variations occur in the material covered by the interview. (2) There are differences in scoring techniques. For example, the interview counts any crying in the infant as negative temperament even though it may be in response to painful trauma. (3) Some mothers may be more likely to choose 1 of the 3 questionnaire options repeatedly as a matter of habit. The considerable discrepancies between the mothers' over-all views of their babies and the actual questionnaire scores, particularly among the more difficult ones, should serve as a warning to the pediatrician not to accept too hastily any superficial impression of a baby's functioning. If he really wants to know what is going on with a baby, he must obtain descriptions of the baby, either by questionnaire or some sort of interview, and then make his own diagnosis. Clinical impressions are of value, however, in interpreting the questionnaire's results, since both it and the interview give equal scores to functions of differing import/race, such as irregularity of sleep and of bowel movements.
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Only 5 of the 9 categories of reactivity are used in the determination of difficult, intermediate, and easy babies. Activity, distractibility, and persistence can be of significance in behavioral problems at a later date but are evidently not of major importance in early infancyY High or low threshold has not seemed to predispose to problems in behavior. In fact, 10 of the 15 very high threshold ratings were in easy babies. If these other 4 categories were eliminated from the questionnaire, it would take even less time to administer and rate without losing its principal value. What can be concluded about the usefulness of. this questionnaire in pediatric practice? 1. If there are no substantial problems in the mother's caring for the baby, the questionnaire could simply define the temperamental characteristics. This may be somewhat of a luxury, but some mothers have reported that just the thought required in answering the questions accurately was helpful in sharpening their perceptions of their babies' functioning. The mother of the one pair of twins in this study was helped to understand that the reason she felt more positively toward one of them was that his style of reacting made him easier for her to understand and respond to. 2. When there is a problem in the motherchild interaction, it is important to know what the contribution of the baby may be. As we have seen, the mother's general impression of the baby may be distorted. More thought must be given to determine the best way to use the questionnaire results in the clinical counseling situation. At present it seems wise to regard it as a screening device, which identifies difficult temperament but requires some additional interviewing to elaborate on these findings and their impact on the mother. 3. In pediatric residency training it is important to introduce the concept of temperamental differences. Having urged residents to consider this aspect of the child, we must provide them with some way to measure it.
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4. Possible research applications are numerous: D o babies with certain temperamental characteristics such as persistence or activity achieve their developmental milestones earlier than others and seem to be brighter than they are? Are others besides the inactive babies 12 more susceptible to the effects of environmental deprivation? Is it quite certain that difficult babies function neurologically just the same as others? H o w does the clinician differentiate reliably between the minimally brain d a m a g e d and the difficult infant? Does the high rate of cesarean sections in this series indicate that obstetric complications, as well as genetic influences, 13 are a factor in the production of temperamental characteristics? There appears to be no simple answer to the p r o b l e m of how to live with a difficult baby. T h e parents of these babies, who seem to be no different from the general population, must be capable of unusual firmness, patience, consistency, and tolerance, lest a destructive interaction result in a lifelong behavioral disability. 2 For example, if the child is slow to adapt and gets upset in new situations, the parents may avoid these new situations for fear that the resulting turmoil will be harmful. His experience is limited narrowly and he becomes less confident of himself. T h e pediatrician can offer sedation for the baby when appropriate, assurance to the parents that they are not responsible by their actions for the baby's unpleasant behavior, and a fairly confident prediction that things will get better eventually if wisely managed. For example, he can counsel the parents of the unadaptable child not to let him back away from a reasonable exposure to new situations. Such babies do get easier to live with if well handled but are likely to show their difficulty later under stress or with new situations. 2 O n e mother of a very difficult baby, who is now a year old, recently re-
The Journal o] Pediatrics August 1970
ported at a routine visit that he has become relatively easy. A m o m e n t later she calmly added that the first week of their summer vacation had been a disaster because the baby had an extremely hard time adjusting to the unfamiliar place. The process of developing the questionnaire and evaluating its worth has been furthered considerably by the cooperation and support of two members of the NYLS team, Doctors Stella Chess and Sam Korn. REFERENCES
1. Thomas, A., Chess, S., Birch, H. G., Hertzlg, M. E., and Korn, S.: Behavioral individuality in early childhood, New York, 1963, New York University Press. 2. Thomas, A., Chess, S., and Birch, H. G.: Temperament and behavior disorders in children, New York, 1968, New York University Press. 3. Chess, S.: Individuality in children, its importance to the pediatrician, J. PEDIAT. 69: 676, 1966. 4. Korn, S.: Personal communication. 5. Wessel, M. A., Cobb, J. C., Jackson, E. B., Harris~ G. S., Jr., and Detwiler, A. C.: Paroxysmal fussing in infancy, sometimes called "colic," Pediatrics 14: 421, 1954. 6. Carey, W. B.: Maternal anxiety and infantile colic. Is there a relationship? Clln. Pediat. 7: 590, 1968. 7. Kron, R. E., Ipsen, J., and Goddard, K. E.: Consistent individual differences in the nutritive sucking behavior of the human newborn, Psychosom. Med. 30: 15I, 1968. 8. Bridget, W. H., and Relser, M., Psychophysiological studies of the neonate, Psychosore. Med. 21: 265, 1959. 9. Lipton, E. L., Steinschneider, A., and Richmond, J.: The autonomic nervous system in early life, New Eng. J. Med. 273: 147, 1965. 10. Escalona, S. K.: The roots of individuality, Chicago, 1968, Aldine Publishing Company. I1. Brazelton, T. B.: The early mother-infant adjustment, Pediatrics 32: 931, 1963. 12. Schaffer, H. R.: Activity level as a constitutional determinant of infantile reaction to deprivation, Child Develop. 37: 595, 1966. 13. Rutter, M., Korn, S., and Birch, H. G.: Genetic and environmental factors in the development of "primary reactive patterns," Brit. J. Soc. Clin. PsychoL 2: 161, 1963.