Evelyn B. Thoman

Visual alertness in neonates as evoked by maternal care

Abstract The object of this study was to explore, within the context of common maternal ministrations, the relative efficacy of contact and of vestibular stimulation, with and without the upright position, in producing visual alertness in neonates. The subjects were 40 crying and 24 sleeping 2- to 3-day-old healthy full-term newborns, equally divided into males and females, breast and bottle-fed infants. Each subject was given, in random order, six interventions which entailed singly, or in combination, contact and vestibular stimulation with or without the upright position. A six-point scale assessing levels of alertness with high interobserver reliability was devised. There were highly significant individual differences in alerting response between the infants, but no differnces due to sex or mode of feeding. In the context of soothing the infant, vestibular stimulation had a highly significant effect on alerting. Contact had little effect on evoking alertness except when combined with vestibular stimulation and the upright. The infants responded minimally when stimulated in the context of rousing. The findings imply that, at least during the neonatal period, the vestibular stimulation which attends most caretaking activities may be more crucial than contact for certain aspects of early human development.

Neonate-Mother Interaction: Effects of Parity on Feeding Behavior.

THOMAN, EVELYN B.; TURNER, ANN M.; LEIDERMAN, P. HERBERT; and BARNETT, CLIFFORD R. Neonate-Mother Interaction: Effects on Feeding Behavior. CHmD DEVELOPMENT, 1970, 41, 1103-1111. A procedure was developed for the study of feeding patterns of mothers with their newborn infants. By means of an automated recording system, time measures of components of bottle feedings were obtained without the presence of an observer. The measures clearly discriminated the feeding behaviors of primiparous and multiparous mothers with their 2-day-old infants. Total observation times, including feeding and nonfeeding activities were significantly longer for the primiparous pairs. The feeding portion of the observations was also longer for the primiparas. Although these mothers were more persistent in their feeding endeavors, they were also less effective in their efforts, as indicated by a lower total consumption of formula by their infants and by a lower rate of formula intake. The findings were related to studies of parity effects on the newborn and research on birth-order effects on older children.

Role of maternal disturbance and temperature change in early experience studies

Abstract This study was designed to compare temperature and maternal variables as possible mediating factors in infantile treatment effects. Groups of infant rats were handled with and without temperature reduction on Days 2–7 after birth. Additional groups were handled with temperature reduction, but one group was returned to the mother cool and the other group was returned to the mother warm. Still another group of pups was untreated, but the mothers were molested in the same way as were mothers of handled animals. As adults, all animals were tested for 4 days in the open field. Following the final testing session, blood samples were obtained for an assay of adrenal corticosterone activity. The measures used in the open field did not discriminate the groups. On the plasma corticosterone measure, regardless of whether or not treatment in infancy had involved a reduction in temperature and regardless of whether they had been returned to the mother cool or warm, all handled groups were significantly lower than the like-sex control group. Furthermore, offspring of the molested mothers, although they had received no direct infantile treatment, also showed a lower corticosterone level than the like-sex control animals. This finding definitely implicates the mother in the early handling effects.

Learning in the neonatal rat

Abstract For the first 3 days after birth, five groups of rats were differentially reared in order to vary learning opportunities. One of the groups was reared in an incubator and tube-fed. The other four groups were reared by foster mothers, and three of these groups were additionally treated with stimulus components of the artificial feeding situation. After only eighteen feedings, or learning trials, incubator-reared pups were found to respond to being handled and to being stimulated with the feeding tube with very active wriggling, squealing and suckling movements, whereas most untreated pups either did not respond or responded negatively to the test stimuli. In a test situation in which a pup could orient towards either a surrogate mother or a live rat mother, the untreated pups did not move to make a choice. Rather than indicating group preferences, this test revealed a striking difference between untreated and incubator-reared pups in their activity level.

Physiological and behavioral consequences of postnatal maternal stress in rats

Abstract To investigate the effects of maternal stress on the offspring, independent groups of lactating rats were subjected to ether anesthesia and jugular venipuncture on Day 3, 6, or 9 post partum, or to shock on Day 3 post partum. At weaning, 162 pups from the litters of these and control mothers were used to assess adrenocortical activity either immediately upon removal from the nest or after 15 min exposure to a novel environment. In addition, 33 males and 33 females were weaned and tested as adults in an avoidance learning situation. Plasma corticosterone levels, both before and after novelty, were significantly higher in the weanling offspring of all treated mothers when compared with those of non-treated mothers. In adulthood the offspring of mothers stressed 3 days post partum were significantly different from all other groups and showed poorer avoidance learning.

Hormonal and behavioral changes in the rat mother as a function of early experience treatments of the offspring

Abstract In order to investigate the long-term effects on the rat mother of early mother-infant manipulations, maternal rats were assigned to groups in which, for 16 days following parturition, the offspring were handled; or rotated among mothers; the mother alone was disturbed; or no treatment was given. Beginning 3 weeks after the litters were weaned, newborn foster pups were placed with the maternal females and maintained with them for 20 days thereafter. Groups of foster pups were alternated between the subjects and lactating females twice daily. The 3 treated groups of rat mothers differed from the controls on each measure taken, in that: the original litters weighed less at weaning, retrieving scores on all tests with the foster pups were higher, lactation was reinitiated earlier, and diestrous cycles were more prolonged during the fostering period. Furthermore, there was a significant negative correlation between retrieving scores and the number of estrous periods that occurred during the fostering period; and also between retrieving and initiation of lactation as measured by milk in the duodenum of the pups. Since the variations in behavior as a function of the early mother-infant manipulations preceded hormonal changes, it was postulated that the behavioral response may act to initiate changes in the central nervous system regulation of the hormones involved in maternal behavior.