Experience and progesterone in ring dove incubation.

Abstract: Doves were tested for progesterone-induced incubation after they had acquired previous experience with from one to five different phases of their initial breeding cycle. A sixth group had no previous breeding experience. Previous breeding experience inclusive of at least the nestbuilding phase of the cycle is a significant facilitator of incubation behaviour induced by injected progesterone, but previous experience with only the courtship phase was not sufficient. Experience with phases additional to nestbuilding increased overall nestresponsiveness without significantly increasing the number of birds incubating. The nature of a ring dove's previous experience is therefore an important influence in its behavioural response to exogenous progesterone. Article: The reproductive cycle of sexually mature ring doves can be divided into a sequence of functional phases: courtship, nestbuilding, egglaying, incubation, and care of young. The organization of the behavioural patterns of each phase and the transitions between phases are influenced by both the external situation and the dove's hormonal condition In an earlier study of the hormonal initiation of incubation, Methods Ninety pairs of sexually-mature ring doves (Streptopelia risoria) of comparable ages at the time of testing were used. All birds lacked reproductive experience at the beginning of the study. The testing cages were breeding cages of wood, measuring 70 x 45 x 35 cm, with dispensers for food, water and grit and having wire-mesh front doors. Isolation cages were double-width hanging rat-cages in racks. Breeding and isolation cages were kept in separate rooms. Lights were clock-controlled (Tork) to turn on at 06.00 hours and off at 20.00 hours E.S.T. Temperature was generally kept between 22° and 24°C

Ohm's Law for a Relativistic Pair Plasma

We derive the fully relativistic Ohm's law for an electron-positron plasma. The absence of non-resistive terms in Ohm's law and the natural substitution of the 4-velocity for the velocity flux in the relativistic bulk plasma equations do not require the field gradient length scale to be much larger than the lepton inertial lengths, or the existence of a frame in which the distribution functions are isotropic.Comment: 12 pages, plain TeX, Phys. Rev. Lett. 71 3481 (1993

Different assessment tasks produce different estimates of handedness stability during the eight to 14 month age period

Using 150 infants (57% males), two common tasks for assessing infant hand-use preferences for acquiring objects were compared for their ability to detect stable preferences during the age period of eight to 14 months. One task assesses the preference using nine presentations of objects; the other uses 32 presentations. Monthly classifications of hand preference for each task were determined by either a commonly used a decision criterion in which one hand is used 50% more often than the other or a criterion based on proportion of hand-use difference that exceeds a conventional alpha probability of 0.05. The seven monthly assessments provided by the two tasks also were examined for latent classes in their developmental trajectories. The two tasks were significantly different for both their identification of latent classes and their monthly classification of the infant’s hand-use preference. The 32 presentations yielded three developmental trajectories (45% right preferring, 5% left preferring, and 50% no clear preference) whereas the nine presentations revealed only two trajectories (70% right, 30% no preference). The nine presentations task, with the 50% proportion decision criterion, was very generous in classifying right and left-preferring infants at each month but produced greater fluctuations across months compared to the 32 presentation task with an alpha decision criterion. Both tasks revealed that a large proportion of infants are still developing a hand-use preference during this age period. Recommendations are made for examining the development of hand-use preferences and their relation to the development of other neuropsychological functions

Do hand preferences predict stacking skill during infancy?

The cascade theory of handedness suggests that hand preferences develop from a history of cascading and sequentially developing manual asymmetries for a variety of actions. Infants who consistently use their preferred hand for a variety of actions likely would gain proficiency using that preferred hand and, consequently, perform more proficiently on other challenging manual tasks. One such task is object stacking, which has been linked with a number of cognitive abilities. If infant hand preference facilitates the development of stacking skill, then this could provide a link by which early hand preference might affect the development of cognition. From a sample of 380 infants assessed for an acquisition hand preference across 6-14 months, 131 infants were assessed for stacking skill from 10 to 14 months at monthly visits. Four unique handedness sub-groups were identified from the 380-infant sample: left, trending right, stable right, or no hand preference. Each of the four hand preference groups exhibited different trajectories in the development of their stacking skills. Left- and stable right-handers stacked more items than infants with no preference by 14 months, whereas infants with a trending right preference did not. The proportion of preferred hand use (right and left) from 6 to 9 months also predicted an earlier initial onset of stacking skill, whereas the proportion of only right hand use did not. Thus, the development of a hand preference predicts an earlier emergence of stacking skill and may have implications for other domains of infant cognitive development

The effect of certain task characteristics on performance on two neuropsychological tests of spatial abilites.

Certain neuropsychological assessments of spatial ability assume that the processing of diagonality and nondiagonality of patterns is equivalent and that processing 2-D representations is equivalent to processing 3-D objects. The Stick Test and the Locomotor Maze Test also assume that successful performance requires the use of mental rotation. Normal adult subjects received either 2-D or 3-D versions of the Stick Test (n = 45) or an unlabeled or labeled version of the maze test (n = 25). Both tests used either nondiagonal or diagonal patterns. More errors were made on 2-D representations of sticks than on the 3-D sticks. Also, more errors occurred with the diagonal than with the orthogonal patterns on both tasks. When maze paths were labeled, fewer subjects made errors on the orthogonal paths than on the diagonal paths. Few subjects reported using mental rotation to perform these tasks. The performance of normal adults may violate the assumptions usually made about a test,s measure of spatial ability

A developmental psychobiological approach to developmental neuropsychology.

Although both developmental psychobiology and developmental neuropsychology examine the interface between biological and psychological processes, they differ in conceptual framework. This article argues for the incorporation into developmental neuropsychology of certain aspects of the conceptual framework of developmental psychobiology. Three principles of dynamic psychobiological interaction are described and applied to four issues in neuropsychology (handedness, sex differences in behavior, critical periods, and modularity of structure–function relations). Then, it is proposed that developmental psychobiology can make four direct contributions to developmental neuropsychology. Finally, it is argued that the value of the conceptual framework provided by developmental psychobiology depends, in part, on how well it translates into procedures that can be applied in the clinical settings of the developmental neuropsychologist

What is embodied: "A-not-B error" or delayed-response learning?

The procedures used to ensure reliable occurrences of the A- not-B error distort and miss essential features of Piaget’s original observa- tions. A model that meshes a mental event, highly restricted by testing pro- cedures, to the dynamics of bodily movement is of limited value. To embody more than just perseverative reaching, the formal model must in- corporate Piaget’s essential features

Maternal influences on infant hand-use during play with toys.

Infant hand-use preferences are related to mother's, but not father's, handedness. Since infants match mother's hand-use during toy play, maternal handedness can affect infant hand-use. Twenty-eight mother— infant pairs (14 left-handed and 14 right-handed infants but all right- handed mothers) were videotaped while playing with six toys on the infant's 7-, 9-, and 11-month birthdays. Play was analyzed for five kinds of hand-use biasing situations, but maternal hand-use was the dominant influence. Infant matching of maternal hand-use increased with age and right-handed infants and female infants matched maternal hand-use more frequently. Concordance of hand-use preference between mother and infant seemed to account for both the matching and the stronger preferences of the right-handed compared to the left-handed infants

Infant Hand Preference and the Development of Cognitive Abilities

Hand preference develops in the first two postnatal years with nearly half of infants exhibiting a consistent early preference for acquiring objects. Others exhibit a more variable developmental trajectory but by the end of their second postnatal year, most exhibit a consistent hand preference for role-differentiated bimanual manipulation. According to some forms of embodiment theory, these differences in hand use patterns should influence the way children interact with their environments, which, in turn, should affect the structure and function of brain development. Such early differences in brain development should result in different trajectories of psychological development. We present evidence that children with consistent early hand preferences exhibit advanced patterns of cognitive development as compared to children who develop a hand preference later. Differences in the developmental trajectory of hand preference are predictive of developmental differences in language, object management skills, and tool-use skills. As predicted by Casasanto’s body-specificity hypothesis, infants with different hand preferences proceed along different developmental pathways of cognitive functioning

Ontogenetic constraints on the evolution of right-handedness.

Ontogenetic factors constrain the evolution of species-typical traits. Because human infants are born “prematurely” relative to other pri- mates, the development of handedness during infancy can reveal impor- tant ontogenetic influences on handedness that may have contributed to the evolution of the human species-typical trait of a population-level right- hand dominance