Food sharing in albino rat pups: Does familiarity breed contempt?

The present experiment investigated the effects of kinship and familiarity upon food sharing in pairs of albino rat pups. Five pairs of rats from each of the following groups were tested: (1) familiar siblings, (2) nonfamiliar siblings, (3) familiar nonsiblings, and (4) nonfamiliar non-siblings. A small food portion was used, necessitating not only close physical contact, but also cooperation in the sense that both pups were required to remain relatively immobile in order for both to feed simultaneously. Results indicated more frequent sharing among unfamiliar pups, whether related or not. Results also indicated that food sharing increased in frequency among all four groups over the 5-day testing period, suggesting that cooperation in the form of food sharing can develop, or increase in frequency, over time in albino rat pups.     

Mirror-image stimulation and short separations in stumptail monkeys

Two experiments examined the responses of infant stumptail macaques (Macaco arctoides) to mirror-image stimulation (MIS) during short social separations. Overall, infants living in pairs showed agitation when separated from their partners, but were calmer when the partner, an unfamiliar peer, or their own mirror image was visible. MIS elicited more facial expressions than the familiar peer, and more affiliative contact than an unfamiliar peer. In contrast, infants reared in a group were not calmed during separations either by an unfamiliar peer or by MIS, and they exhibited some negative reactions to the mirror. Social responsiveness to MIS varies with the social background of the subjects.     

Differences on Bayley's infant behavior record for a sample of high-risk infants and their controls

3 groups of high-risk newborns and their controls were assessed at 92 weeks post-conceptional age using Bayley's Infant Behavioral Record (IBR). The 3 groups of high-risk infants were those who weighed 1,500 grams or less at birth and required no ventilator therapy, those weighing 1,500 grams or less at birth who required ventilator therapy, and newborns weighing more than 1,500 grams at birth who required ventilator therapy. Controls were healthy term infants matched for 7 socioeconomic and demographic variables. The first principal component of the IBR ratings for the 3 groups of high-risk infants and the controls were similar. All 3 groups of high-risk infants received less desirable IBR ratings on most items than their controls. In addition, there were some differences among high-risk groups; ventilated infants regardless of birth weight received the lowest ratings reflecting overall performance on the IBR, very low birthweight, ventilated newborns were more likely to receive ratings characterizing an overly active infant with a short attention span, and very low birth-weight, never-ventilated infants were most likely to be rated as happy but passive and delayed. The differences between the high-risk infants and controls in large part resulted from infants who were also delayed in terms of their mental and motor development.     

Psychological factors capable of preventing the inhibition of antibody responses in separated infant monkeys

The capacity of infant squirrel monkeys to mount an antibody response to viral challenge was evaluated after removal from their mothers in several social and physical environments. Control and separated infants were injected with a benign virus, the bacteriophage X174, and levels of neutralizing antibody were assessed for 3 weeks. Infants separated alone in an unfamiliar environment showed a significant reduction in antibody levels as compared to control infants. Allowing infants to remain in the home environment, either alone or with peers, prevented this inhibition of antibody responses from occurring. Similarly, providing familiar peers in the novel environment facilitated the normal expression of antibody responses. These results indicate that the trauma of maternal separation is significantly reduced when infants are familiar with the separation environment or familiar social companions are available. The reduced antibody response was associated with the highest level of adrenal activation induced by the unfamiliar separation condition, but antibody titers and plasma cortisol levels could not be specifically correlated in individual infants.     

Radial localization of odors by human newborns.

To study sensitivity to radial location of an odor source, 20 human newborns, ranging from 16 to 130 hours of age, were presented with a small amount of ammonium hydroxide. The odor source was placed near the nose slightly to the left or right of midline, with its position randomized over repeated trails. Direction of headturn with respect to the odor location and diffuse motor activity were scored from the videotape recordings of the newborns' behavior. It was found that as a group, the newborns turned away from the odor source more frequently than they turned toward it. The tendency to turn away from the odor was stronger in infants who displayed less motor activity after the response. Newborns also exhibited a right bias in the direction of the head movements. It is concluded that a spatially appropriate avoidance response is present in the neonate and that the newborn is innately sensitive to the radial location of an odor.     

Newborn response to auditory stimulus discrepancy

Newborns were assessed for their recovery of head turning toward laterally presented auditory stimuli (titi) that varied from a familiar standard on 1 of 5 levels of fundamental frequency. Following habituation to repeated standard trials, newborns recovered to 14% and 21%, but not to 0%, 7%, or 28% discrepancies, indicating that recovery was a quadratic function of the degree of stimulus-schema discrepancy. Moreover, newborns reliably turned away from the standard stimulus during posthabituation no-change control trials, indicating that the neural network associated with that stimulus was not fatigued. Infants in every condition showed recovery of head turning to a novel posttest stimulus (papa). These data are interpreted with a dual processing model postulated to include both reflexive (context-independent) orientation and stimulus-schema comparison process (context-dependent) orientation.     

When half a word is enough: infants can recognize spoken words using partial phonetic information

Adults process speech incrementally, rapidly identifying spoken words on the basis of initial phonetic information sufficient to distinguish them from alternatives. In this study, infants in the second year also made use of word-initial information to understand fluent speech. The time course of comprehension was examined by tracking infants' eye movements as they looked at pictures in response to familiar spoken words, presented both as whole words in intact form and as partial words in which only the first 300 ms of the word was heard. In Experiment 1, 21-month-old infants (N = 32) recognized partial words as quickly and reliably as they recognized whole words; in Experiment 2, these findings were replicated with 18-month-old infants (N = 32). Combining the data from both experiments, efficiency in spoken word recognition was examined in relation to level of lexical development. Infants with more than 100 words in their productive vocabulary were more accurate in identifying familiar words than were infants with less than 60 words. Grouped by response speed, infants with faster mean reaction times were more accurate in word recognition and also had larger productive vocabularies than infants with slower response latencies. These results show that infants in the second year are capable of incremental speech processing even before entering the vocabulary spurt, and that lexical growth is associated with increased speed and efficiency in understanding spoken language.     

The affective response of Down's syndrome infants to a repeated event

In a study with 17 Down's syndrome infants, the older infants (mean age = 20 months, 6 days) responded to the regular reappearance of a squeaky doll with significantly more affective behavior than did younger infants (mean age = 9 months, 24 days). When the 10 younger infants were included in a longitudinal study of their responses to this same event, the onset of affective behavior was significantly correlated with the mental development index of the Bayley Scales of Infant Development, and was also associated with some aspects of temperament as measured by the Carey Survey of Temperamental Characteristics: these aspects were poor adaptability to change and a low tendency to approach new situations.     

Holistic face processing in newborns, 3-month-old infants, and adults: evidence from the composite face effect

Holistic face processing was investigated in newborns, 3-month-old infants, and adults through a modified version of the composite face paradigm and the recording of eye movements. After familiarization to the top portion of a face, participants (N = 70) were shown 2 aligned or misaligned faces, 1 of which comprised the familiar top part. In the aligned condition, no visual preference was found at any group age. In the misaligned condition, 3-month-olds preferred the face stimulus with the familiar top part, adults preferred the face stimulus with the novel one, and newborns did not manifest any visual preference. Results revealed that both infants' and adults' eye movements may be affected by holistic face information and demonstrated holistic face processing in 3-month-olds.     

Verbal and Behavioral Responsiveness to the Cries of Atypical Infants

A total of 176 subjects (53 male students, 65 female students, and 58 mothers) were exposed to 1 of 6 types of infant cries coming from an adjacent room while their behavioral and affective responses were observed. The cries were the pain cries of 2 normal newborns, 1 infant with maladie du cri du chat, 1 with Down syndrome, 1 asphyxiated infant with brain damage, and one asphyxiated infant without brain damage. Subsequently the subjects rated the overhead cry on a series of affective, attributional, and perceptual dimensions. The results indicated that the 6 cries differentially affected the subjects' affective, self-reported, and behavioral responses, as well as their tendency to report not hearing the cry. In general, the findings suggested that the highest- pitched cries (those of the asphyxiated infants), in comparison to the lowest-pitched cries (those of the normal and Down infants), elicited less optimal responses from the listeners.     

Infants' attentional responses to frequency modulated sweeps

In 3 experiments, the attentional responses of 4-month-old infants to frequency-modulated (FM) sweeps corresponding to the frequency range of adult-to-infant and adult-to-adult intonation patterns were assessed. In Experiment 1, infants were observed to discriminate "exaggerated" (i.e., adult-to-infant) FM sweeps from "normal" (i.e., adult-to-adult) FM sweeps in a habituation-dishabituation paradigm but did not selectively attend to one over the other. In Experiment 2, where the same stimuli were used in a paired-comparison paradigm, again no differential attention was observed. In Experiment 3, the most exaggerated sweep was paired against a continuous, monotonic pure tone, but again no difference in salience was observed. These data suggest that the extent of modulation or intonation of an auditory stimulus per se does not constitute a salient cue for infants' attention to sound.     

牛奶伴侣燕麦饼干的生产工艺研究

根据人体营养结构需求,利用牛奶、燕麦为原材料,开发具有营养保健功能且符合人类膳食结构的牛奶伴侣燕麦饼干品种,探索其生产工艺流程和合理配方.     

Responses of Free-ranging Rhesus Monkeys to a Natural Form of Social Separation. I. Parallels with Mother-Infant Separation in Captivity

Observations of 23 free-ranging rhesus monkey infants on Cayo Santiago, Puerto Rico, indicated that mothers' first postpartum estrous periods were marked by large increases in the amount of time infants were separated from their mothers, by disturbances in mother-infant relationships, and by increases in infant distress behavior. When their mothers resumed mating, most infants showed signs of agitation; a few briefly showed indications of depression. Male infants responded to their mothers' resumption of mating by playing more, whereas females engaged in less play and more allogrooming. The results suggest ( a ) that basic parallels exist between the behavioral responses of rhesus infants to their mothers' resumption of mating in the field and to forcible separation from their mothers in captivity and ( b ) that early separation experiences may play a role in the normal development or manifestation of sex differences in behavior.     

Stranger responses: effects of familiarity, stranger's approach, and sex of infant

Most investigators examining contextual influences on infant responses to a stranger have limited their study to the initial responses of the infant. Few have considered infant reactions beyond the first minutes of the encounter or the enduring effects of contextual variables once mothers have left. The present study examines the effects of stranger's style of approach, familiarity with the stranger, and infant sex on infant response before and after maternal separation. Familiarity was operationalized in 2 ways: the length of time mothers stayed before leaving infants with the stranger and meeting the stranger a second time. Findings suggest that all these factors influence infant behavior. Ifants looked and smiled at the stranger significantly more when approached slowly. Contrary to expectations, infants (particularly girls) who met the familiar stranger after 1 week protested significantly more when left with her at that time. Trends indicate the length of time mothers stayed was least influential since most infants became extremely distressed once mothers departed.     

Adult male--infant interactions among monkeys living in nuclear families.

Adult male rhesus monkeys were housed in nuclear families containing adult female mates, offspring, and other infants and adults. Behaviors exhibited by the adult males were recorded 4 days per week over a 37-month period; in interactions involving other monkeys, the identity and the responses of those participants were also recorded. The results indicated that, although adult males were less active and more stable in their behavioral levels than mates or offspring, they clearly distributed both initiates and responses differently to male offspring, female offspring, mates, and both infant and adult monkeys from other families. These results suggest that adult males have the potential to play more important roles in the social development of infants than had been previously suspected on the basis of field data. Implications for human father-infant interactions are discussed.     

Concentrations of sex hormones in umbilical-cord blood: their relation to sex and birth order of infants.

In 3 groups of human newborns, 5 sex hormones were assayed from samples of umbilical-cord blood, and concentrations were analyzed by the sex and birth order of the infants. The 5 hormones assayed were testosterone, androstenedione, estrone, estradiol, and progesterone. Concentrations of testosterone were significantly greater in males than females. The other 4 hormones did not differ significantly by sex. In both sexes, firstborns had significantly more progesterone and estrogens, with progesterone showing the largest birth-order effects. Among male infants, firstborns had higher concentrations of testosterone. The higher concentrations of progesterone in firstborns of both sexes, and of testosterone in firstborn boys, were found not to be due to length of labor, birth weight, or maternal age. However, they were a function of temporal spacing of childbirths. Later borns who were closely spaced in relation to their next-older siblings had lower concentrations of hormones. The effect of temporal separation was greater on male than female infants for each of the 5 hormones studied. The results are discussed in terms of the possible effects of hormone "depletion" on the psychological development of closely spaced later borns.     

Temperament and attachment security in the strange situation: an empirical rapprochement

In response to Frodi and Thompson's recent demonstration that infants classified A1-B2 in the Strange Situation differ significantly in emotional expression from infants classified B3-C2, several longitudinal data sets were examined to determine whether these group differences might be a function of infant temperament. Data from 3 separate samples revealed significant concordance between infant-mother and infant-father Strange Situation classifications when scored in terms of A1-B2 versus B3-C2, but not when scored in terms of the traditional A-B-C system. In addition, in 2 samples on which newborn behavioral data were available, A1-B2 infants displayed more autonomic stability than B3-C2 infants, and in one of the samples the former infants were more alert and positively responsive as newborns (with means in the same direction in Sample 2). Moreover, mothers of A1-B2 infants described their babies as less difficult to care for at 3 months of age. Considered together, these findings suggest that infant temperament affects the manner in which security or insecurity is expressed rather than whether or not the infant develops a secure or insecure attachment. These findings are discussed in terms of their implications for the study of the interactional antecedents and the developmental consequences of attachment security.     

Defensive Behaviors in Infant Rhesus Monkeys: Ontogeny and Context-dependent Selective Expression

We examined the ontogeny of the infant rhesus monkey's defensive behaviors and the ability to modulate them in response to specific environmental cues. Rhesus infants in 4 age groups (N = 8 per group) were briefly separated from their mothers and tested under 3 conditions: alone, in the presence of a human who averted his gaze, and in the presence of a human staring at them. Infants as young as 0 to 2 weeks displayed defensive behaviors but did not selectively respond to the human's presence or direction of gaze. By 9 to 12 weeks of age, infants modulated their responses in relation to the parameters of the threat. At this age, infant rhesus monkeys undergo cognitive and emotional changes associated with brain development similar to those in human infants 7 to 12 months old. This also is the time when human infants engage in complex emotional and behavioral responses to threatening situations. Understanding the development and expression of defensive behaviors in infant monkeys should be applicable to similar issues in emotional development of human infants.     

Perceiving "outside the box" occurs early in development: evidence for boundary extension in three- to seven-month-old infants

This investigation examined whether infants display boundary extension-a tendency to remember more of a visual scene than was presented. Three- to 7-month-olds were familiarized with a photograph of a visual scene, and tested with wide-angle versus close-up views of the scene. Infants preferred the close-up, indicating that they perceived the wide angle (the one consistent with boundary extension) as more familiar. Converging experiments showed that: (a) infants did not spontaneously prefer the close-up, (b) adults did not judge the wide angle to be more similar to the familiarization stimulus, and (c) infants spontaneously preferred the close-up when the photographs depicted outline objects without backgrounds. The findings suggest that infants anticipate information that lies beyond the borders of a scene view.