摘要:

AbstractA series of experiments was undertaken to both discover and explore the causes of sexually dimorphic phenotypic asymmetries in infant and adult Mongolian gerbils. We found that (1) the order in which the eyes of individual gerbil pups opened varied with their gender; right eyes of female pups opened before left eyes, while left eyes of male pups opened before right eyes, and (2) the paw that adult gerbils held in the air while maintaining a species‐typical tripedal stance varied with gender; female gerbils held their right paws in the air significantly more often than did male gerbils. Both order of eye opening and laterality of paw use while in a tripedal stance varied significantly as a function of the intrauterine position which subjects had occupied as fetuses. These data implicate exposure to testosterone as a mediator of the development of asymmetries exhibited by Mongolian gerbils. © 1993 John Wiley&Sons, I

ISSN:0012-1630    

DOI:10.1002/dev.420260402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThis study examined whether hand/object size ratios define common boundaries to the grip configuration patterns of infants and adults. A group of 5‐ to 8‐month‐old infants and a group of adults engaged in a displacement grasping task with inverted cups that varied in size. The findings showed that infant and adult grip configurations varied systematically with object size: More digits were brought into the contact grip configurations with increasing object size. Furthermore, when object size was scaled to hand size, common dimensionless ratios defined the grasping patterns and transitions between grasping patterns in a similar manner for both adults and infants. Consistent with a dynamical view of the development of coordination, the strong role of body scale on the developmental prehensile coordination pattern was observed for a given set of task constraints. © 1993 John Wiley&Son

ISSN:0012-1630    

DOI:10.1002/dev.420260403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractHow many and what kinds of processes mediate infant visual attention? Are they influenced by stimulus “complexity?” Analyses were performed on visual fixation data from ninety 4‐month‐old infants; the time each infant spent looking at a black and white checkerboard pattern containing either 4 × 4, 12 × 12, or 20 × 20 checks per picture was measured for eight 10‐s trials, with 10‐s interstimulus intervals (Kaplan&Werner, 1986). Correlational and factor analyses revealed one significant source of individual variability (or factor) in the 4 × 4 data, and two significant sources in the 12 × 12 and 20 × 20 data. One factor gained strength over progressive trials and accounted for decreases in looking time. A second factor gained strength over the first few trials, then lost strength over the remaining trials, and accounted for initial increments in looking time. The two factors are consistent with a dual‐process model of infant response dynamics; the first may represent habituation, a decremental process, and the second may represent sensitization, an incremental process that is activated by “complex” stimuli. © 1

ISSN:0012-1630    

DOI:10.1002/dev.420260404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe current study extends previous documentation of behavioral asymmetries in hand‐to‐mouth, self‐consoling behaviors of infant chimpanzees. The underlying source of lateralized hand‐to‐mouth, self‐calming behavior was investigated by comparing individual differences in neonatal arousal levels, regulatory ability, and motor performance with individual differences in the degree of laterality at 3 months. Asymmetrical hand‐to‐mouth, self‐calming behaviors at 3 months of age were significantly related to general arousal at 2 days of age (i.e., the Range of State cluster scores measured by the Brazelton Neonatal Behavioral Assessment Scale). Simply stated, chimpanzees with a right‐hand bias in hand‐to‐mouth behavior exhibited lower arousal at 2 days of age compared with nonright‐handed individuals. The only item of the Range of State cluster to distinguish subjects was irritability: Right‐handed subjects were less irritable. Previously, a trend was reported with respect to sex differences in the laterality of hand‐to‐mouth behavior. With the greater number of subjects in the present study, we found that females exhibited a significantly greater right‐hand bias for hand‐to‐mouth behaviors (12 of 13) than did males (9 of 15). We conclude that neonatal arousability, and not regulatory capacity or motor performance, predicts the degree of laterality found in hand‐to‐mouth, self‐calming behaviors in 3‐month‐old chimpanzees. These data are discussed from the standpoint of early pari‐parturitional or intrauterine factors affecting lat

ISSN:0012-1630    

DOI:10.1002/dev.420260405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0012-1630    

DOI:10.1002/dev.420260401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY