Cardiac and behavioral interrelationships in the reactions of infants to strangers.

Recorded cardiac and various behavioral reactions of 80 5- and 9-mo-old infants to strangers to determine (a) whether the shift with age from attentiveness to fearfulness of strangers is accompanied by a shift from heart rate (HR) deceleration to acceleration; (b) whether testing infants in the presence of the mother attenuates cardiac and behavioral manifestations of stranger distress; and (c) whether the direction of HR change is related to the direction of change of facial expression, even when age is held constant. Results are generally positive. Behavioral data confirmed that most 5-mo-olds were not frightened by the stranger, and many but not all 9-mo-olds were. HR responses also changed with age, being predominantly deceleratory to the stranger at 5 mo of age and acceleratory at 9 mo. The accelerations were of much greater frequency and larger magnitude when 9-mo-olds were tested in the mother's absence. In contrast, behavioral reactions were not significantly affected by the mother's absence. The direction of HR responding was linked at both ages to affective expression: Whether 5 or 9 mo of age, behaviorally distressed Ss gave progressively acceleratory responses, whereas behaviorally undistressed Ss did not. It is concluded that future studies can profit from careful recording of both HR and behavioral expression in the infant. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depth perception in Mongolian gerbils (Meriones unguiculatus) and spiny mice (Acomys russatus and A. cahirinus).

Studied depth perception in gerbils and spiny mice with a modified visual cliff that varied the height of a platform from 5.08 to 25.4 cm and presented Ss with an apparent drop-off to a patterned or a white field. Ss were 6 8–22 mo old female gerbils and 12 7–28 mo old spiny mice. Time to descend from the platform and orienting response frequency were recorded. For gerbils, neither measure varied significantly between the platforms. Both mice species increased descent time and orienting response frequency as platform height increased. Results suggest that both gerbils and spiny mice perceived depth, though there appeared to be a difference between the species' use of sensory cues in descending from a visual cliff. The spiny mice appeared to rely more on visual cues than did the gerbils. Data also reveal subtle behavioral differences between the mice species that may relate to their successful sympatry. Results are discussed by alluding to ecological differences between these species in their natural habitats. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Security of attachment and stranger sociability in infancy.

Examined the relationship between stranger sociability and the security of the infant–mother attachment relationship in 43 infants observed at 12? mo and again at 19? mo of age. The sociability measure was a sequential-initiatives procedure and was followed by the Ainsworth Strange Situation (ASS). Reaction in the ASS allowed Ss to be classified as securely attached (B), avoidant (A), or resistant (C). Subgroups within these classifications reflect variation in reunion behaviors. At both ages, Ss in subgroups B? and B? had the highest sociability scores, whereas A? and C? Ss had the lowest. Analysis of the relationship between stranger sociability and interactive behaviors in the ASS revealed the centrality of a distal interactive mode in both contexts. Because of a high incidence of family change, only 53% of Ss had the same overall attachment classification at both ages. Sociability scores at 12? and 19? mo were highly correlated when attachment status was temporally consistent. Absolute changes in sociability scores reflected a similar pattern of results. Cross-lagged correlational analyses suggested that predictive relationships with the security of attachment are meaningful only when attachment status itself is consistent over time. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-modal and intramodal transfer as predictors of mental development in full-term and preterm infants.

25 full-term (FT) and 33 preterm (PT) infants who had participated in studies of cross-modal (CM) and intramodal (IM) transfer at 12 mo of age were seen at older ages to assess the predictive validity of these early measures for later cognition. FT Ss were administered the Bayley Scales of Infant Development at 24 mo of age; PT Ss were administered these scales at 12 and 24 mo of age, the Stanford-Binet Intelligence Scale (Form L-M) at 34 and 40 mo of age, and the Wechsler Intelligence Scale for Children—Revised and the Developmental Test of Visual-Motor Integration at 6 yrs of age. For FT Ss, both 12-mo measures were significantly related to 24-mo Bayley Mental Development Index (MDI) scores; for PT Ss, both 12-mo measures were related not only to 24-mo Bayley MDI but to each subsequent measure of cognitive outcome through 6 yrs. 12-mo IM scores were highly correlated with the 6-yr assessment of visual–motor integration. A measure of object permanence obtained at 12 mo was also related to cognitive outcome, but not so consistently as were the other 2 12-mo measures. Although parental education was a significant predictor beginning at 24 mo, multiple regression analyses indicated that the CM and the IM measures substantially increased the percentage of variance in outcome that could be accounted for by parental education alone. (61 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory deficits associated with senescence: A neurophysiological and behavioral study in the rat.

Neurophysiological and behavioral measures were obtained from 32 senescent (28–34 mo) and 32 mature adult (10–26 mo) Long-Evans hooded rats. Extracellularly recorded synaptic responses were obtained from electrodes chronically implanted in the fascia dentata and perforant path. Ss were first tested on a circular platform, which favored the use of spatial cues for its solution; the senescent Ss exhibited poorer memory for the rewarded place. When granule cell synaptic responses were recorded after a single session of very brief high-frequency stimulation, the amount of elevation and time course of decline were equivalent between age groups. After 3 repetitions, however, young Ss maintained the increased synaptic strength for at least 14 days, whereas old Ss declined after the 1st session. The amount of synaptic enhancement was statistically correlated with the ability to perform the circular platform task both within and between groups. Furthermore, the aftereffects of the high-frequency stimulation selectively impaired the old Ss' spontaneous alternation behavior on a –T maze. Results are discussed in terms of the synaptic theory of memory formation and the aging process. (78 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Les enfants anxieux-isolés sont-ils inhibés dans un contexte de nouveauté sociale?

Studied correlations between social behaviors in nursery school and social behaviors in novel situations to test genetic vs environmental theories of social withdrawal in early childhood. Ss were 30 preschool children (mean age 46 mo) of average social competence, 30 socially competent preschool children (mean age 47 mo), 30 aggressive-irritable preschool children (mean age 46 mo), and 28 anxious-withdrawn preschool children (mean age 45 mo). Ss were assigned to their respective groups on the basis of socioaffective ratings provided by their nursery school teachers. Each S's social behaviors were observed in 2 novel situations involving the S's own mother as well as another mother–child dyad. Intergroup differences in measures of sociability vs social inhibition were analyzed, and the effects of the mother's behaviors toward her child were determined. A French version of the Preschool Socioaffective Profile (P. J. LaFrenière et al, 1990) was used. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of recursive awareness of intention.

24 Ss (aged 3–9 yrs) played a card game against an adult opponent that required strategic actions indicating recursive awareness of intention. Behavioral measures of success indicated that recursive strategies were used by Ss aged 5 yrs and older but not by 3-yr-olds. Verbal indicators of recursion showed a developmental lag relative to the behavioral measures. Ss appeared to be better at retaliating against deceptive strategies than at initiating them. First-level awareness of the opponent's visual processes appeared at younger ages than did recursive awareness of intention. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental analysis of behavioral dysfunction in rats with septal lesions.

At 7 days of age, 48 male Long-Evans hooded rats received lesions of the septal nuclei or control operations. Ss then received 30 hrs of training on a DRL 20-sec schedule for 1 hr/day beginning at either 27 or 96 days of age. At 126 days of age, all Ss received 10 additional training sessions. After operant testing, all Ss received 10 additional training sessions. After operant testing, all Ss were tested on spontaneous alternation, spatial reversal, and passive avoidance. Results indicate that on a DRL 20-sec schedule Ss that received lesions of the septum neonatally and were tested at different ages performed in a similar manner. Approximately 50% of the Ss with lesions of the septal nuclei reached efficiency levels comparable with those of normal controls. When tested for retention, these efficient Ss still performed similarly to normal Ss. Ss with septal lesions were facilitated in the acquisition of a spatial habit, were deficient in spatial habit reversal, were less likely to demonstrate spontaneous alternation, and were deficient in passive avoidance. It is concluded that neonatal lesions of the septal nuclei produce permanent behavioral impairments on a diversity of measures and that, although juvenile animals with limbic system damage often manifest behaviors different from adult Ss, the difference is not evident during operant testing (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Father, mother, and stranger as elicitors of attachment behaviors in infancy.

Compared fathers with mothers and strangers as elicitors of attachment behaviors in 10 male and 10 female infants from each of 3 age groups (10, 13, and 16 mo). Differential proximity-seeking behavior, distress vocalization, and stranger eye contact from a "secure base" were used to index attachment. Fathers were superior to strangers as elicitors of attachment behaviors but 2nd to mothers at all age levels. When both parents were present, Ss approached mothers twice as often as fathers. Tested with each parent separately, they traveled to the mother in a shorter time than they traveled the same distance to the father and spent more time near the mother. The amount of eye contact with strangers was greater when Ss were near mothers as compared to fathers. Distress vocalization during separation from the parents was one of the few measures which did not discriminate between mothers and fathers. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social and nonsocial behaviors of adult rhesus monkeys after amygdalectomy in infancy or adulthood.

At 6 yrs of age, 6 female rhesus monkeys that had sustained bilateral amygdalectomy in infancy and 5 intact controls were transferred to an observation cage where behaviors were recorded while the Ss were alone, paired with unfamiliar stimulus animals, and paired with familiar Ss from the opposite experimental group. The 5 adult controls then underwent amygdalectomy, and all tests were repeated with the infant- and adult-operated Ss. Infant-operated Ss changed behaviors more rapidly than did intact controls in social and nonsocial situations, and their activity levels were less modified after a 24-hr period in the observation cage. They were subordinate to intact controls but expressed less fear than did controls when briefly placed with an unfamiliar aggressive animal. Adult amygdalectomy produced many changes in behavior, but these were identical to those observed in like-age monkeys that had been amygdalectomized in infancy. Infant-operated monkeys demonstrated more behavioral deficits at 6 yrs than they had earlier in life. (49 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What do babies listen to most? A developmental study of auditory preferences in nonhandicapped infants and infants with Down's syndrome.

Studied the auditory preferences of 10 Down's syndrome (DS; mean CA 12.4 mo; mean MA 9.3 mo) and 10 nonhandicapped (NH; mean CA 9.3 mo; mean MA 9.6 mo) infants at the developmental ages of around 9 and 18 mo. An apparatus that allows infants to choose to listen to 1 of a pair of auditory stimuli and that records their responses was used. At both ages, Ss had the choice of listening first to either a children's rhyme or a repetitive tone and then to either the mother talking to her own child (baby talk) or the mother talking to an adult. At both ages, both groups of Ss significantly preferred to listen to the children's rhyme and to the baby talk. At 9 mo, both groups listened significantly more to nursery rhymes than to spoken stimuli; by 18 mo, NH Ss showed a significant increase in listening to baby talk, which they then listened to longer than to rhymes. DS Ss showed a significant decrease in listening to baby talk at this age and still listened longer to rhymes. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender labeling and the adoption of sex-typed behaviors.

A gender-labeling task was used to test the ability of 21 girls and 22 boys ranging in age from 21 to 40 mo to discriminate between pictures of boys and girls and male and female adults. Ss who passed the gender task (mean age 30 mo) were compared with Ss who failed it (mean age 26 mo) on 3 behaviors most often categorized as sex typed (toy choice, aggression, and peer playmate selection). It was predicted that Ss who passed the task would choose more sex-typed toys and same-sex peers and that there would be a drop in aggression for girls who passed but no change for boys. Results confirm the predictions for aggression and peer choice but not for toy choice. The relation between the child's understanding of gender categories and environmental influences is discussed. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of prefrontal cortex ablation in neonatal, juvenile, and young adult rats.

Long-Evans hooded rats sustaining lesions in the medial (MF) or the orbital (OF) prefrontal cortex at various ages (10, 25, 40, or 60 days postnatally) were tested as adults on a series of behavioral tasks that are known to be sensitive to such lesions in adults. On spatial alternation learning, both the 40- and 60-day MF Ss were seriously impaired, whereas neither the 10- nor the 25-day MF Ss differed from controls. On a hoarding task, 25- and 60-day MF Ss hoarded less food than either controls or 10-day MF Ss. Lesions of OF cortex in males at 40 or 60 days significantly increased running-wheel activity; OF lesions in both sexes at 25 days of age or later decreased the rate of continuous reinforcement reacquisition relative to controls, whereas 10-day OF Ss did not differ from controls on either task. Thus, Ss with lesions of either frontal area at 10 days of age showed complete behavioral sparing on all measures. The effects of lesions at later ages varied with the behavioral task employed and with lesion locus. Although the 10-day Ss received a somewhat longer postoperative recovery interval than most of the later operates, these results cannot be explained on the basis of recovery time alone. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rudiments of infant temperament: Newborn to 9 months.

Assessed temperament for 110 newborn twins drawn from 23 male–male twin pairs, 21 female–female pairs, and 11 opposite-sex pairs, using a comprehensive neonatal examination that focused on irritability, resistance to soothing, activity, and reinforcement value. The same Ss were later assessed at 9 mo in a structured laboratory setting. Summary ratings of emotional activity were compiled for each S, representing the preponderant reaction of the S in both settings. Individual differences were markedly evident, ranging from wailing distress to smiling and contentment. The neonatal variables correlated significantly with emotional tone at 9 mo, and a further analysis revealed a generalized multiple correlation between the neonatal variables and the 9-mo measures of temperament. When extreme groups on emotional tone were selected at 9 mo (crying and distress vs smiling and contentment), the groups were significantly discriminated by their neonatal scores, with 70% of the Ss being correctly assigned to the appropriate extreme group. Overall, the irritable, difficult-to-soothe neonate was likely to be fussier and more distressed in the laboratory assessment than the more tractable neonate. The results affirm a significant predictive linkage between neonatal behaviors and later measures of temperament and thus give credence to the premise of some stability in infant temperament. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemispheric changes in information processing during development.

Hemispheric processing of visually presented words and pictures was examined in 3 groups of Ss with mean ages of 8 yrs 8 mo, 12 yrs 3 mo, and 27 yrs 9 mo (154 Ss). Pictorial or symbolic stimuli were presented singly to either the right or left visual hemifield. Ss had to decide whether the 1st stimulus in a pair matched the 2nd stimulus. The major results were that (a) age groups differed in the strength of lateral differences, and (b) for all age groups, the right hemisphere was significantly faster in processing unmatched stimuli. Results suggest that lateral specialization of the left hemisphere is not complete until adolescence and that over the age range tested, the left hemisphere becomes progressively more specialized for the processing of matched data. (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Undernutrition by rearing in large litters delays the development of reflexive, locomotor, and memory processes in mice.

In 3 experiments with a total of 512 Swiss-Webster mice, the effects of early postnatal undernutrition on the ontogeny of several behavioral capacities of varying complexity were investigated. After birth, mouse pups in all experiments were reared in either normally nourished or undernourished conditions by maintaining litter sizes at 6 or 16, respectively. Exps I and II examined the development of adultlike patterns of swimming behaviors and spontaneous locomotor activity, respectively, as a function of litter size. The maturation of both behavior patterns was delayed by about 2 days in the 16-litter mice. In Exp III, normally-nourished and undernourished Ss received 25 trials in a shock–escape T-maze at 9, 11, and 13 days of age, followed by similar retention tests 24 hrs later. Although litter size had little effect on correct turns at each age during training, Ss reared in litters of 6 showed significant retention of prior training by 12 days of age, whereas comparable retention was not noted for the large litter mice until 14 days of age. Results suggest that nutritional deficits, imposed by rearing in large litters during the postnatal period of rapid CNS maturation, retard the development of behavioral capacities involving both unlearned and learned responses. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Toward an animal model of Type A behavior.

Attempted to differentiate behaviors of Mongolian gerbils analogous to Type A (coronary-prone) and Type B (non-coronary-prone) human behavior. Preliminary classification of 20 Ss was based on performance on differential reinforcement of low rates 20-sec and 60-sec schedules. To retain their preliminary classification, Type A and Type B Ss were required to be dominant and subordinate, respectively, in matches with Ss of opposite behavioral classification. Ss that exhibited Type A timing won significantly more dominance matches than did Type B Ss. Incidence rates of Type A and Type B behavior in the 2 selectively bred generations were significantly greater than frequencies in the original stock. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interplay among behavioral systems: Illustrations from the study of attachment, affiliation, and wariness in young children with Down's syndrome.

42 Down's syndrome (DS) children, age 30–42 mo, were seen in M. D. Ainsworth and B. A. Wittig's (1969) "strange situation" to assess the interrelationships among the affiliative, attachment, and fear/wariness behavioral systems. A stranger evoked affiliative behaviors in Ss but also elicited wariness and attachment behaviors. The emergence, sequence, and intensity of these behavioral systems varied with the context and the behaviors of both stranger and mother. The finding that more than one behavioral system was activated suggests that an explanation of social responsiveness must be sufficiently broad and integrative to encompass different but interrelated behavioral systems, with their respective functions and determinants. Despite certain quantitative and qualitative differences, behavioral systems appear to be similarly organized in DS and normal children. It is argued that the behavioral organization manifested by the retarded children supports and extends E. Zigler's (see record 1969-08608-001) "developmental" position. These findings suggest that the DS group constitutes a legitimate target of research for elucidating the processes of normal and deviant development. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shifting strategies for behavioral thermoregulation in developing golden hamsters.

Studied developmental changes in the golden hamster pup's capacity for behavioral temperature regulation. Groups of 3 pups aged 4-24 days were tested at room temperature (22°C), on a strong gradient (34-22°C), and on a mild gradient (30-22°C). The proportion of time engaged in the following behaviors was recorded: contact with the warm edge (thermotaxis), active huddling, and quiet huddling. Results show that Ss tested at 22° engaged in active huddling, and their temperature dropped rapidly. Only on Day 14 were they able to maintain their temperature constant with a combination of vigorous exploration and quiet huddling. On the strong gradient, Ss were able to regulate their temperature at all ages. Young Ss (4-5 days) depended on thermotaxis rather than huddling, separating when their temperature started to rise. With age, quiet huddling replaced thermotaxis as a dominant behavior. On the mild gradient, Ss combined active and quiet huddling with thermotaxis, so that their temperature dropped at a slow steady rate. It is concluded that hamster pups have a well-developed capacity for behavioral temperature regulation. Whether they attempt to keep their temperature constant or tolerate a slow rate of drop depends on the amount of exogenous heat available, which under natural conditions would be supplied predominantly by the mother. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)