Chance, choice, and the future of reproduction

The evolution of reproduction has been characterized by the development of complex biological and behavioral mechanisms that serve to regulate chance events. Human reproduction has been characterized by the increasing importance of individual choice. Some contemporary manifestations of this broad trend are the high incidence of contraceptive and "proceptive" behavior among couples in Western, industrialized nations. The former behavior willingly attempts to prevent conception while the latter actively attempts to induce conception (such as concentrating intercourse around the time of ovulation). Both patterns of behavior indicate that a choice is being made. A 3-year study of 1000 women revealed proceptive behavior as the most important factor predicting occurance of conception among married couples in the United States. The general strategeis people follow while making childbearing decisions: termination, sequencing, and pre-planning form a continuum following the historical trend toward greater reproductive control. In the terminating strategy, a couple makes no decision about child bearing until the number of children they have become enough or too much. In the sequencing strategy, decisions to have children are made 1 child at a time until a satisfactory limit is reached. In the pre-planning strategy, a plan is worked out ahead of time and is subsequently carried out. As new reproductive technology is introduced and as progressive change is made in society's reproductive related values and beliefs, choice will continue to dominate chance as the highly likely trend for the future of reproduction. Surrogate maternity is just 1 example of this trend. However, these new options, which culminate in the theory and practice of "progensis," (still in its infancy), as well as offering a rich opportunity, can also incur psychological burdens on a couple. Thus, as with any kind of freedom, these developments will require care, caution and responsibility.     

Temporal reproduction

A signal appeared for a certain time period. After the period elapsed, pigeons had to begin and complete a sequence of 15 responses in a time window ranging from the signal duration to 50% longer. Sessions involved as many as 10 different signal durations occurring in a random sequence. The times produced by pigeons often were in the same ranges as those that have been found with adult human subjects. The average times were described equally well as linear or power functions of signal duration. However, instead of the overestimation of durations usually found when animals have timed the duration of antecedent stimuli, the linear functions suggested that the pigeons underestimated the durations of their own behavior. The birds showing the strongest control when the conditions involved eight or 10 different duration requirements revealed the constant coefficients of variation that support Weber's law and scalar timing theory. Scalar timing in temporal differentiation appears to depend on non-ambiguous information about the duration required for reinforcement and on a high degree of sensitivity to the duration requirement.     

Humane reproduction

Discusses social, economic, and humane considerations in population control. Mental health aspects of controlled fertility are considered in relation to the family's psychosocial and material resources, the effects of reproduction on the individual the family, and community, and the advantages and disadvantages of controlled reproduction. A distinction between family planning and population control is outlined. It is suggested that there is hardly a single more effective tool for preventing psychological disorders than the prevention of unwanted pregnancies. Analyses of educational and medical services and methods of birth control are presented. A comprehensive neighborhood health station, which would consolidate these services, is suggested. It is concluded that humane programs of reproduction would lead to a reconciliation of biological drives with a responsible concern for the quality of life.     

The reproduction of intelligence

Although a negative relationship between fertility and education has been described consistently in most countries of the world, less is known about the relationship between intelligence and reproductive outcomes. Also the paths through which intelligence influences reproductive outcomes are uncertain. The present study uses the NLSY79 to analyze the relationship of intelligence measured in 1980 with the number of children reported in 2004, when the respondents were between 39 and 47 years old. Intelligence is negatively related to the number of children, with partial correlations (age controlled) of ?.156, ?.069, ?.235 and ?.028 for White females, White males, Black females and Black males, respectively. This effect is related mainly to the g-factor. It is mediated in part by education and income, and to a lesser extent by the more “liberal” gender attitudes of more intelligent people. In the absence of migration and with constant environment, genetic selection would reduce the average IQ of the US population by about .8 points per generation.     

Bartlett revisited: Direct comparison of repeated reproduction and serial reproduction techniques

Bartlett developed the procedures of repeated reproduction (the same person repeatedly recalling information) and serial reproduction (people transmitting information from one person to another). Our experiment directly compared recall accuracy across these two techniques, which has not previously been reported, using DRM word lists. Recall of the initial study list words remained constant across repeated reproductions but declined markedly across serial reproductions. In contrast, recall of associated words that were not originally studied (i.e. critical words) was steady across both conditions. Because more of the original list words were forgotten across each link of the serial reproduction chain, the proportion of critical items recalled (relative to list words) increased significantly as the list passed between people. Using output bound scoring, serial reproduction resulted in lower accuracy than repeated reproduction by the final recall trial. Our results are broadly consistent with Bartlett's (1932) informal observations: Serial reproduction produces greater forgetting of the original material than does repeated reproduction and also leads to greater distortion relative to the proportion of correct material recalled.     

Heritage space,multiple temporalities,and the reproduction of Guangzhou Overseas Chinese Village

This paper investigates the everyday experiences of long-term residents during the urban heritage revitalization process of Guangzhou Overseas Chinese Village (GOCV) as China's first overseas Chinese village. Drawing upon insights from the recent theories of multiple temporalities, this paper argues that the everyday sensory experiences of long-term residents during the urban heritage revitalization process can be understood through three interconnected temporal modes (past, present, and future). These modes reflect the sociopolitical context of different periods and influence the everyday rhythms and practices of community residents. Specifically, regarding the past, patriotic fervor, a shared identity, and the experience of living collectively have created a “happy home for returned overseas Chinese”. In terms of the present, the market-oriented reform and commodification of housing has had a profound impact on the built forms and meaning systems of the neighborhood, leading to long-term residents' nostalgia for the past and resistance to present changes in the everyday rhythms. Lastly, based on an envisioned future, long-term residents carry out specific preservation practices to maintain and enhance their place identity. This article explores the approaches to enrich the urban heritage research by illuminating the importance of temporality for understanding the spatial (re)production of living urban heritage.     

Care and the self: biotechnology,reproduction, and the good life

This paper explores a novel philosophy of ethical care in the face of burgeoning biomedical technologies. I respond to a serious challenge facing traditional bioethics with its roots in analytic philosophy. The hallmarks of these traditional approaches are reason and autonomy, founded on a belief in the liberal humanist subject. In recent years, however, there have been mounting challenges to this view of human subjectivity, emerging from poststructuralist critiques, such as Michel Foucault's, but increasingly also as a result of advances in biotechnology itself. In the face of these developments, I argue that the theoretical relevance and practical application of mainstream bioethics is increasingly under strain. Traditionalists will undoubtedly resist. Together, professional philosopher-bioethicists, public health policymakers, and the global commercial healthcare industry tend to respond conservatively by shoring up the liberal humanist subject as the foundation for medical ethics and consumer decision-making, appealing to the familiar tropes of reason, autonomy, and freedom.     

Numerical reproduction in pigeons

Pigeons were trained to match the number of responses made during a production phase to the number of keylight flashes (2, 4, or 6) in a previous sample phase. In Experiment 1, there were 2 conditions in which the flashes were programmed to occur at a constant rate or within a constant overall duration. For both conditions, although accuracy was relatively low, responding increased linearly with flash number and coefficients of variation decreased. Positive transfer to novel numbers was obtained only when test and baseline trials had the same temporal organization, but multiple regressions revealed significant control by number independently of temporal cues. In Experiment 2, flashes were programmed to occur pseudorandomly to degrade the validity of temporal cues. Results were similar to in Experiment 1. A prototype response class model accounted for the major features of the data. According to the model, responses during the production phase are shaped into higher order units that are associated with different stimulus numbers and function as a rough category scale of numerosity.     

Sequencing of behaviors in Aplysia fasciata: integration of feeding, reproduction, and locomotion.

To begin studying the neural basis of higher-order decision-making in Aplysia fasciata, we examined individual bouts of behavior in various conditions of access to food and/or mates. We then determined rules governing transitions between bouts. The data indicate that a single intermediate condition, moving in place, may be centrally related to transitions between behaviors. In all conditions, over 85% of all transitions between behaviors were via moving in place. Moving in place tended to precede and follow other categories of activity (crawling, swimming, immobile), and feeding. Also, moving in place apparently represents a fixed proportion of all bouts of behavior. In each condition, moving in place represented approximately 40% of all bouts, while the number of bouts of other behaviors varied markedly. After a bout of moving in place there was a strong tendency for the animal to return to the behavior performed before moving in place. Additional preferred sequences of behavior were also seen. Courtship tended to precede mating, and crawling preceded swimming.     

Time reproduction, working memory, and behavioral inhibition in children with ADHD.

Barkley (1997a) proposed that the central deficit in Attention Deficit Hyperactivity Disorder (ADHD) is in behavioral inhibition, resulting in deficits both in working memory and sense of time. To test this theory, 21 children with ADHD and a matched sample (ages 6-13) completed a variety of tasks that measured behavioral inhibition, working memory, attention, and time reproduction. Children with ADHD performed significantly below controls on measures of inhibition, attention, and time reproduction. They did not differ significantly from controls, however, on tasks of working memory. In addition, performance on the working memory tasks was not correlated with the time reproduction task. We discuss the relevance of these results in the context of current theories of ADHD.     

The reproduction of vertical and oblique orientations in the visual, haptic, and somatovestibular systems

This study investigates whether the vertical orientation may be predominantly used as an amodal reference norm by the visual, haptic, and somato-vestibular perceptual systems to define oblique orientations. We examined this question by asking the same sighted adult subjects to reproduce, in the frontal (roll) plane, the vertical (0°) and six oblique orientations in three tasks involving different perceptual systems. In the visual task, the subjects adjusted a moveable rod so that it reproduced the orientation of a visual rod seen previously in a dark room. In the haptic task, the blindfolded sighted subjects scanned an oriented rod with one hand and reproduced its orientation, with the same hand, on a moveable response rod. In the somato-vestibular task, the blindfolded sighted subjects, sitting in a rotating chair, adjusted this chair in order to reproduce the tested orientation of their own body. The results showed that similar oblique effects (unsigned angular error difference between six oblique orientations and vertical orientation) were observed across the three tasks. However, there were no positive correlations between the visual, haptic,     

Daily variation of multiple behaviors in Aplysia fasciata: integration of feeding, reproduction, and locomotion

Daily variations in feeding, reproductive behaviors, and activity level were examined under three conditions: (1) animals had access to food and mates; (2) there was access only to food; (3) neither food nor mates were present. Behaviors differed in amplitude of variations from their daily mean value. Egg-laying had the strongest tendency to be clustered. Amplitude of variations in courtship and swimming was larger than those of immobility, crawling, and feeding, while moving in place was the least clustered behavior. Changes in state affected the tendency to be clustered. When food and mates were present, amplitude of variations became progressively larger for immobility, moving in place, crawling, and swimming. Behaviors differed in the degree to which variations were patterned as a 1/day oscillation. Relatively little of the variability in crawling, moving in place, courtship, and egg-laying was due to a 1/day oscillation under any condition. By contrast, a large proportion of the variability of immobility, swimming, mating, and eating was modulated by a 1/day oscillation in at least one condition. The contribution of a 1/day oscillation to variability differed in the conditions examined. For immobility and swimming, when food and mates were present, the 1/day component of variability became smaller. By contrast, presence of mates led to an increase in the 1/day component of variability modulating feeding. Daily peaks of swimming and feeding were in phase with one another, and out of phase with mating and feeding. The ratio of locomotion to inactivity is constant, independent of change in external conditions. However, this ratio varied throughout the day. When food and mates were absent, variations of immobility and swimming were strongly related to variations in the inactivity ratio. When food and mates were added, this tendency decreased. The data suggest that daily variations in occurrence of behaviors can be accounted for by interactions between oscillators affecting Aplysia behavior and motivational variables. A 1/day oscillator has strong effects on mating, swimming, and immobility. The effect of the oscillator is modified by changes in motivational state.     

On additivity of duration reproduction functions

In the present paper properties of theoretical response functions in the duration reproduction task (drt) are studied. If the drt response is to be interpreted as the measure of a temporal duration elapsed in the past, the reproduction function (rf) must be additively measuring. The additivity property is defined for bivariate rfs, taking into account the delay between retention and reproduction. The requirement that an rf be additively measuring leads to a system of two functional equations, which are solved by (i) linear functions of time, or (ii) functions of the form yielded by the ‘dual klepsydra model’ of duration reproduction [Wackermann, J., & Ehm, W. (2006). The klepsydra model of internal time representation and time reproduction. Journal of Theoretical Biology, 239, 482-493]. This result supports the outstanding rôle of the ‘klepsydraic reproduction function’ (krf) in models of internal representation and reproduction of temporal durations.     

Movement cue reproduction under preselection

A series of three experiments was undertaken to determine the role of prior knowledge of different movement cues in the preselection effect. Experiments 1 and 2 examined the singular and combinative role of location and extent cues under both preselected and constrained conditions. The third experiment provided a framework for evaluating the sources of informations which may contribute to the preselection phenomenon. In experiments 1 an 2, the results suggest the advantage of preseleted over constrained movement was constant across movement cues. The second experiment demonstrated that the dual cue condition was superior to location alone and extent alone in both accuracy and consistency. Finally, the third experiment indicated that prior knowledge (strategy) was the primary variable responsible for the preselection effect.     

The differential contribution of executive functions to temporal generalisation,reproduction and verbal estimation

Evidence from dual-task studies suggests that executive resources are recruited during timing. However, there has been little exploration of whether executive recruitment is universal across temporal tasks, or whether different temporal tasks recruit different executive resources. The current study explored this further by examining how individual differences in updating, switching, inhibition and access affected performance on temporal generalisation, reproduction and verbal estimation tasks. It was found that temporal tasks differentially loaded onto different executive resources. Temporal generalisation performance was related to updating and access ability. Reproduction performance was related to updating, access and switching. Verbal estimation performance was only related to access. The results suggest that executive resources may be recruited when monitoring and maintaining multiple durations in memory at the same time, and when retrieving duration representations from long-term memory. The findings emphasise the need to consider timing behaviour as the product of a wide range of complex, integrated, cognitive systems, rather than as the output of a clock in isolation.