Children's sensitivity to social contexts at 18 months of age.

Investigated whether, in an unfamiliar, semipublic place, children as young as 18 mo of age would be sensitive to variations in the nature of social encounters between their mothers and an unfamiliar adult (E). Measures of the child's distance from the mother at the beginning of each 10-sec interval of the encounter, the percentage of 10-sec intervals spent by the child on the stranger's side of the room, frequency of child vocalizations to the mother, times child made physical contact with the mother, and frequency of smiling show that 18-mo-old children are already sensitive to background contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Socially induced delayed reproduction in female Mongolian gerbils (Meriones unguiculatus): Is there anything special about dominant females?

In 4 experiments, the authors explored effects of interaction with both sexually active adult female and unfamiliar adult male Mongolian gerbils (Meriones unguiculatus) on young female gerbils' ages at first parturition. Presence of a natural mother retarded development of her daughters. However, presence of a natural mother had no greater effect on her daughters' development than did presence of any other familiar animal, either male or female. Further, exposing young female gerbils to an unfamiliar male accelerated their development even when their reproductively active mothers were present. The data indicate that maintaining young female gerbils in stable family groups results in both inhibition of sexual maturation (caused by exposure to familiar individuals) and failure to activate sexual development (caused by lack of exposure to unfamiliar males). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social organization predicts nature of infant-adult interactions in two species of wild guinea pigs (Cavia aperea and Galea monasteriensis).

The authors compared interactions of infants with mothers and unfamiliar females in a novel environment in 2 caviomorph rodent species: the harem-living Cavia aperea, the probable progenitor of the domestic guinea pig; and the pair-living Galea monasteriensis. In C. aperea, interactions with mothers and unfamiliar females were largely similar; in G. monasteriensis, interactions with the mother, but not unfamiliar female, were characterized by physical closeness and sociopositive behavior. In G. monasteriensis, plasma cortisol levels were lower when with the mother than when with the unfamiliar female. Results are consistent with the species' social organizations and suggest that behavioral interactions of pups with mothers and other females in domestic guinea pigs reflect primarily the social organization of the progenitor species rather than domestication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting boys' social acceptance and aggression: The role of mother–child interactions and boys' beliefs about peers.

Seven- to 9-year-old boys (N?=?177) and their mothers participated in this study in which the associations between boys' experiences with their mothers, their beliefs about familiar and unfamiliar peers, and their peer adjustment were examined across a 2-year period. Boys' negative behavior with mothers was associated with their having more negative beliefs about familiar and unfamiliar peers and with their being more aggressive and less well-liked. Beliefs about familiar peers predicted changes in boys' social acceptance, whereas negative beliefs about unfamiliar peers predicted changes in aggression. In addition, boys' beliefs about peers changed in response to their social experience. The implications of these findings for children's social development are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavior of mother rats in conflict tests sensitive to antianxiety agents.

The purpose of this investigation was to observe the behavior of mother rats in conflict tests. In the punished drinking test, in which licking from a water spout is punished by electric shocks, mothers (observed on Day 1 postpartum following 24 hr of water deprivation) were found to drink more than virgins. Mothers (Day 1 postpartum) also consumed more food than controls in an unfamiliar open field. In contrast, no difference between mothers (Day 5 postpartum) and virgins was present in the exploration of an electrified shock probe. The largest maternal anticonflict effects in the drinking and feeding tests were recorded when the females were tested with their pups. Increased punished drinking was also observed in virgin rats treated with the anxiolytic benzodiazepine midazolam. Following 24 hr of water deprivation, unpunished drinking was higher in lactating females than in virgins, so the increased acceptance of punishment by mothers might have been due to their being more thirsty than virgins. However, virgins, deprived of water for 48 hr and whose unpunished drinking was similar to that of mothers deprived for 24 hr, did not accept as many punishments as the lactating females. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Early weaning in the rat: Effects on whole-brain RNA and free amino acids.

Each of 67 CAW:CFE(SD)spf rat litters was reared with its mother or with its mother and a virgin female ("aunt"). At pup age 15 days, some litters were deprived of their mothers, some remained with mothers whose nipples were cauterized to prevent suckling, and some remained intact until 21 days when all pups were housed individually or in peer groups until tested at 56 days. While increases in whole-brain free aspartic acid were attributed to loss of opportunity for suckling since they occurred in pups without mothers or with cauterized mothers, decreases in brain RNA caused by deprivation were prevented by the presence of mother or aunt. Rearing with aunts increased brain weight and emotional reactivity. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Causes and consequences of natal dispersal in root voles, Microtus oeconomus

To test the causes and consequences of variation in natal dispersal in root voles we released 53 matrilines (mothers with newly weaned litters) separately in field enclosures, during nine consecutive periods. The matrilines could disperse and distribute themselves among three pre-emptied habitat patches. Two dispersal measures were recorded: short-distance dispersal defined as individuals immigrating to a neighbouring patch, and long-distance dispersal defined as unsettled individuals captured along the fence of the enclosures. We analysed the role of social factors (i.e. maternal and litter characteristics), habitat quality (i.e. seasonal effect) and experimentally manipulated shape of the natal patch in dispersal. The consequences of dispersal were analysed with respect to the spatial distribution of kin, and to pregnancy in females and sexual maturation in males. Dispersal was unrelated to patch shape. In agreement with the inbreeding avoidance hypothesis, long-distance dispersal was male biased and philopatric males were most frequently reproductively inactive. Whilst young males avoided their mother, they seemed to disperse, settle and mature sexually independently of their sisters. In agreement with the resource competition hypothesis, young females avoided their mother and were most frequently reproductively inactive when residing in their mother's patch. We conclude that inbreeding avoidance was underlying the male dispersal pattern. For females, long-distance dispersal was most in agreement with the inbreeding avoidance hypothesis while short-distance dispersal could be explained by the resource competition hypothesis. (c) 1998 The Association for the Study of Animal Behaviour.     

Arousal reducing properties of attachment objects: Testing the functional limits of the security blanket relative to the mother.

Investigated whether the properties of social and nonsocial attachment objects would be differentially reduced by inducing a high arousal state. Ss were 23 females and 25 males (ages 21-41 mo) whose mothers rated their intensity of blanket attachment on a 10-point scale ranging from no attachment to extremely strong attachment. Ss were randomly assigned to either a mother-, blanket-, or no familiar object-present (control) condition, forming 6 groups of 8 Ss. To raise arousal levels both physiologically and behaviorally, prerecorded clicking noises were broadcast at 85 dB on a variable time 10-sec schedule, and median room illumination was reduced from 64.0 to .11 footcandles. Results show that the presence of the mother led to significantly more repeated play, longer contact with the familiar object, more frequent contact with and closer proximity to it, greater distance from the escort and the exit, more locomotor activity, and longer delay of crying than no familiar object or than blanket (regardless of whether the child was blanket attached). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Growth of social play with peers during the second year of life.

To assess the social interactions between unfamiliar peers, 30 pairs of home-reared children-10 pairs in each of 3 age groups, 10-12, 16-18, and 22-24 mo of age-were observed in an unfamiliar play setting with their mothers. The children contacted their mothers little and interacted more with toys and one another, exchanging smiles, vocalizations, and toys and imitating each other's actions. Contact with the same objects and involvement in the peer's activities with objects increased reliably with age. By 2 yrs of age, social play exceeded solitary play and the social partner was most often the peer. Results suggest that children generalize to peers' behaviors developed through child-adult interaction, but that peers provide stimulation differing from that of familiar adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral and developmental consequences of early rearing experience for captive giant pandas (Ailuropoda melanoleuca).

Mother-reared (MR) and peer-reared (PR) captive giant panda (Ailuropoda melanoleuca) cubs were compared to evaluate the effects of early removal from mother on behavioral development. Males and females and twins and singletons were compared to assess the effects of social setting on behavioral development. Subjects included 2 PR females, 3 MR females, 3 MR males, and 3 mothers. MR cubs spent more time manipulating bamboo and fell more often than PR cubs. PR cubs spent more time inactive. Male cubs directed more playful behavior at their mothers. Twins spent more time play fighting with their mothers than with their siblings. The results suggest that peer-rearing does not provide young pandas with the same level of social stimulation as mother-rearing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Urine marking and maternal aggression of wild female mice in relation to anogenital distance at birth

A series of experiments were conducted with wild house mice to verify the effect of intrauterine position on females' anogenital distance at birth (AGD) and to examine the relationships between a female's AGD, used as a bioassay of androgen exposure during fetal life, and her social behavior and reproductive success in adulthood. Experiment 1 showed that cesarean-delivered females that developed in utero between two males (2 M females) have significantly longer AGD's than females positioned between two females (0 M females). We then categorized naturally delivered females shortly after birth as having a long, medium or short AGD. In adulthood, these females were tested for their behavior towards unfamiliar pups, their rate of urine-marking in response to a variety of social stimuli, postpartum aggression and success in protecting their litters in response to male and female intruders. Adult females with different AGD's at birth did not differ either in their behavior toward pups or in their rate of urine marking. Conversely, males housed across a wire mesh partition from a long-AGD female deposited a higher number of urine marks than those exposed to a short-AGD female. When tested after delivering a litter, long-AGD females displayed more tail-rattling (a component of agonistic behavior) towards intruders of both sexes in comparison to short-AGD females. These results are consistent with the hypothesis that females with a long AGD are exposed to higher levels of Testosterone during fetal life than females with a short AGD. Although not related to AGD, other measures of maternal aggression were affected by postpartum day, sex of intruders and a female's infanticidal potential while a virgin.     

Female sexual preferences differ in Mus spicilegus and Mus musculus domesticus: the role of familiarization and sexual experience

Mating systems correspond to particular ecological conditions and result from proximate interactions between individuals. We compared the mating preferences of female mice of two species: the house mouse, Mus musculus domesticus, and the mound-builder mouse, Mus spicilegus. Because of differences in their habitat, we expected to observe differences in their sexual preferences. We studied female preferences for a familiar or an unfamiliar male and the occurrence of copulation with the unfamiliar male, during two states of female sexual activity: (1) the postpartum oestrus of paired females, to evaluate the stability of their sexual partnership; and (2) the oestrus of females familiarized with a male, to study the mechanisms underlying their sexual preferences. In the polygamous house mouse, postpartum oestrous females did not show a clear preference between their familiar male and the unfamiliar one. Moreover, oestrous females, familiarized with a male (without sexual interactions), preferred an unfamiliar male and copulated with him. In contrast, postpartum oestrous females and oestrous females of M. spicilegus preferred their familiar male and rarely copulated with the unfamiliar male. This study indicates a strong pair bond in established breeding pairs in M. spicilegus and shows that this bond can be established by familiarization, which is not the case in M. m. domesticus. Our study suggests the existence of monogamous traits in M. spicilegus in contrast to the polygamous M. m. domesticus. (c) 1998 The Association for the Study of Animal Behaviour.     

Peers as primary attachment sources in yearling rhesus monkeys (Macaca mulatta).

Peer bonds were examined in 2 experiments using juvenile rhesus monkeys to determine (1) whether specific attachment bonds are formed between age-mates, (2) whether preferred age-mates can provide a secure base, and (3) whether a previous attachment bond affects the quality of subsequent attachment bonds. In Exp 1, 8 peer-only reared (POR) monkeys demonstrated a specific preference for a predicted favorite peer when given a choice between a familiar and 2 unfamiliar peers. In Exp 2, POR Ss were placed in a novel setting with either their most preferred peer, a familiar but not preferred peer, or an unfamiliar peer, and their responses were compared with those of a 2nd group of monkeys, reared for their 1st 6 mo of life by their mother. Both mother-reared (MP) and POR monkeys displayed significantly more intimate contact and significantly less distress when with their most preferred peer; nevertheless, even when they were with their most preferred peer, POR Ss exhibited more distress than MP Ss. Findings are discussed with reference to current attachment theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synchrony, pseudosynchrony, and dissynchrony: Measuring the entrainment process in mother-infant interactions.

We examined a new method for studying synchrony (i.e., the coordination of movement between individuals in social interactions) in two studies. Raters viewed video clips of interactions and judged the level of synchrony occurring between a mother and a 14-month-old child. Some of the video clips were genuine interactions, but most were pseudointeractions artificially constructed from the genuine interactions via split-screen editing techniques. For mothers interacting with their own children, genuine synchrony was significantly higher than pseudosynchrony, a difference that increased with time. When mothers interacted with an unfamiliar child, however, genuine synchrony was not higher than pseudosynchrony. In fact, mothers with unfamiliar children showed a state of dissynchrony (levels of genuine synchrony significantly lower than levels of pseudosynchrony). Our results suggest that synchrony can be reliably rated, thus allowing future investigations to include such measurements when studying social interaction processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory basis of maternal attachment in ducklings (Anas platyrhynchos) under simulated naturalistic imprinting conditions.

The presence of broodmates during the imprinting process results in peer imprinting that interrupts a visually mediated maternal attachment. We sought to determine the conditions in which group-trained mallard ducklings (Anas platyrhynchos) acquire a maternal attachment. At 48 hr of age, ducklings were allowed to follow a vocal, stuffed mallard hen individually or in groups of 4. Individual ducklings showed a preference for the silent, familiar mallard over an unfamiliar pintail. Ducklings trained in groups did not show a preference. When the mallard maternal call was present during testing, group-trained ducklings overwhelmingly responded to it regardless of whether it came from the familiar mallard or an unfamiliar pintail. Training ducklings in groups, which simulates the natural social context of imprinting, results in peer imprinting. Thus, early in development the young become visually imprinted to each other, and the maternal call mediates attachment to the mother. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of olfactory cues on sexual behavior in the brown lemming, Lemmus trimucronatus..

Tested 3 groups of 12 female lemmings each to determine the effects of odor familiarity on measures of reproductive behavior. A familiar odor (FO) group was exposed to the bedding of a particular male for 1 wk, then tested with that male. A 2nd female group (unfamiliar odor; UO) was exposed to the bedding of a male for 1 wk, then tested with a different male. A 3rd group (control; CO) was not exposed to male bedding prior to being tested with a male. The FO females engaged in higher frequencies of contact social behaviors than did UO and CO females. Males with FO females ejaculated more frequently than did the males with UO and CO females. Latencies to first display of sexual behaviors (female:lordosis; male:mount, thrust, and ejaculation) were lower for FO pairs. Results suggest that previous exposure of females to the odor of a given male facilitates sexual behaviors when such females are later paired with that male. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Patterns of social preference across different social contexts in golden lion tamarins (Leontopithecus rosalia).

We investigated the role of mutual and circumstantial factors in maintaining exclusive social relationships in a New World primate. Four breeding pairs of golden lion tamarins (Leontopithecus rosalia rosalia) were allowed to interact with their mate or an unfamiliar, opposite-sex adult in each of 4 different social contexts: in view of the mate, out of the mate's view, with only the mate present, and with only the unfamiliar animal present. Males and females were in proximity to, approached, and sniffed their mates significantly more often than they did unfamiliar tamarins. These behaviors suggest a preference for the familiar mate. However, when mates were absent, tamarins demonstrated significantly higher levels of approach and sniffs toward unfamiliar animals. These patterns of behavior indicate that circumstantial factors, such as social context, may regulate social interactions between paired tamarins and unfamiliar, opposite-sex conspecifics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ontogeny of dam–young recognition in captive Belding's ground squirrels (Spermophilus beldingi).

Investigated in 3 experiments the development of dam–young discrimination in Belding's ground squirrels by observing 8 dams retrieve unweaned young and by observing social interactions between dams and weaned young. Pups were cross-fostered at birth in order to examine how genetic relatedness (related or unrelated) and rearing association (familiar or unfamiliar) influenced discrimination. On Days 1 (24 hrs after fostering), 8, and 15 (Exp I), dams retrieved pups indiscriminately, but on Day 22 (about the time of weaning) dams retrieved familiar young (those they had reared) faster than unfamiliar young. On Day 29 (Exp II), familiar dam–young pairs were less agonistic during paired-encounter tests than were unfamiliar pairs. Results suggest that (a) dam–young discrimination is based on rearing association rather than genetic relatedness per se, and (b) discrimination emerges around weaning when dams and alien young first encounter each other under field conditions. In Exp III, olfactory cues seemed crucial to discrimination as determined by an olfactory impairment using zinc sulfate. (61 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxytocin receptor activity in the ventrocaudal periaqueductal gray modulates anxiety-related behavior in postpartum rats.

Postpartum rats are less anxious than diestrous virgin females, a phenomenon requiring that mothers have recent contact with their infants. Oxytocin (OT) is one of many neurochemicals released intracerebrally while mothers interact with infants, and we investigated whether OT receptor activity in the ventrocaudal periaqueductal gray (cPAGv) contributes to mothers' reduced anxiety. Infusion of the highly specific OT receptor antagonist, desGly-NH?,d(CH?)?[D-Tyr2,Thr?]OVT, into the cPAGv reduced the percentage of time dams spent in the open arms of an elevated plus-maze, but had no effect on the open-arm behavior of diestrous virgins. Conversely, after separating dams from their litters for 4 hr to increase anxiety, a lower (2 ng) but not higher (5 ng) dose of OT infused into each hemisphere of the cPAGv doubled the percentage of time dams spent in open arms, but did not do so in virgins. OTergic manipulations inconsistently affected risk-assessment behaviors (stretch-attend postures, head dips) in both virgins and dams. Therefore, OT receptor activation in the cPAGv is an important consequence of contact with infants that reduces some anxiety-related behaviors in mother rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Providing attachment objects to facilitate learning and reduce distress: Effects of mothers and security blankets.

Evaluated the effects of the presence of an attachment object on preschoolers' emotionality and discrimination performance in a novel learning situation. Maternal ratings were used to select 30 blanket-attached and 30 blanket-nonattached children. Either their mother, security blanket, or no familiar object was nearby while the Ss could key press for candy reward when a cue was given. Ss with mothers and blanket-attached Ss with blankets demonstrated no differences in discrimination performance and distress postponement, but they were superior to blanket-nonattached Ss with blankets and to Ss with no familiar object available. It is concluded that both social and inanimate attachment objects may serve to reduce young children's anxiety in novel situations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)