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461.
462.
Symmetry and transitivity of conditional relations in monkeys (Cebus apella) and pigeons (Columba livia)
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D'Amato MR Salmon DP Loukas E Tomie A 《Journal of the experimental analysis of behavior》1985,44(1):35-47
In Experiment 1 six monkeys were tested with discriminative relations that were backward relative to their training in a 0-second conditional (“symbolic”) matching procedure. Although there was some indication of backward associations, the evidence was generally weak, and statistical evaluations did not reach conventional significance levels. Unlike children, who show backward associations to the point of symmetry, monkeys and pigeons display at best only weak and transient backward associations. In Experiment 2 associative transitivity was assessed across two sets of conditional matching tasks. All four monkeys tested demonstrated strong transitivity. In contrast, in Experiment 3 there was no evidence of transitivity in three pigeons tested under conditions closely comparable to those of Experiment 2. These results may identify some key features of interspecies differences and contribute to analyses of serial learning in animals. 相似文献
463.
Pigeons' responses were reinforced on two identical and concurrently available chain variable-interval-schedules. Unlike the typical concurrent chains procedure, both links were operative throughout, thus producing three types of concurrency: (1) concurrent initial links; (2) concurrent initial and terminal links; (3) concurrent terminal links. Choice proportions in each of these three states suggested that the pigeons were sensitive to momentary likelihoods of reinforcement: choice proportions for a schedule were higher when the schedule had been operative for some time, resulting in a higher probability of reinforcement. The study also showed that the relative rates of responding did not match the relative rates of reinforcement in any of the three states of concurrency. Instead, the choice proportions in both the concurrent initial and in the concurrent terminal links were intermediate between the scheduled and the obtained relative rates of reinforcement, while the choice proportions for a terminal link concurrent with an initial link consistently overmatched the relative interreinforcement times (and were typically 1.00). These data indicate that an accurate characterization of choice may not be obtained by considering only the relative interreinforcement interval where one interreinforcement interval is segmented into a chain. Instead, the organism's choice for a schedule will be substantially lowered by the chaining operation. 相似文献
464.
465.
Pigeons' responses in the presence of two concurrently available (initial-link) stimuli produced one of two different (terminal-link) stimuli according to identical but independent variable-interval schedules. Responding in the mutually exclusive terminal links was reinforced with food according to fixed-ratio schedules for six pigeons and according to fixed-interval schedules for two pigeons. None of the pigeons matched the proportion of (choice) responses in the initial links to the proportion of the rates of reinforcement obtained during the terminal links. Instead, as the values of each of the terminal-link schedules were increased by a constant amount, the choice proportions for the stimulus associated with the smaller of the two values increased, even though the relative rates of reinforcement during the terminal links decreased. These results are incompatible with those from previous studies with aperiodic (variable-interval or variable-ratio) schedules. The present results do suggest, however, that in transforming aperiodic schedules into their periodic equivalents, it may be necessary to consider the size of the smallest interreinforcement interval comprising the terminal-link schedules. 相似文献
466.
467.
Keuleyan E 《Science and engineering ethics》2010,16(1):43-58
Humanity entered the twenty-first century with revolutionary achievements in biomedical research. At the same time multiple
“dual-use” results have been published. The battle against infectious diseases is meeting new challenges, with newly emerging
and re-emerging infections. Both natural disaster epidemics, such as SARS, avian influenza, haemorrhagic fevers, XDR and MDR
tuberculosis and many others, and the possibility of intentional mis-use, such as letters containing anthrax spores in USA,
2001, have raised awareness of the real threats. Many great men, including Goethe, Spinoza, J.B. Shaw, Fr. Engels, J.F. Kennedy
and others, have recognized that liberty is also a responsibility. That is why the liberty to decide now represents an acknowledged
necessity: biomedical research should be supported, conducted and published with appropriate measures to prevent potential
“dual use”. Biomedical scientists should work according to the ethical principles of their Code of Conduct, an analogue of
Hippocrates Oath of doctors; and they should inform government, society and their juniors about the problem. National science
consulting boards of experts should be created to prepare guidelines and control the problem at state level. An international
board should develop minimum standards to be applicable by each country. Bio-preparedness is considered another key-measure. 相似文献
468.
Israel has a long history of concern with chemical and biological threats, since several hostile states in the Middle East
are likely to possess such weapons. The Twin-Tower terrorist attacks and Anthrax envelope scares of 2001 were a watershed
for public perceptions of the threat of unconventional terror in general and of biological terror in particular. New advances
in biotechnology will only increase the ability of terrorists to exploit the burgeoning availability of related information
to develop ever-more destructive bioweapons. Many areas of modern biological research are unavoidably dual-use by nature.
They thus have a great potential for both help and harm; and facilitating the former while preventing the latter remains a
serious challenge to researchers and governments alike. This article addresses how Israel might best (1) prevent hostile elements
from obtaining, from Israel’s biological research system, materials, information and technologies that might facilitate their
carrying out a biological attack, while (2) continuing to promote academic openness, excellence and other hallmarks of that
system. This important and sensitive issue was assessed by a special national committee, and their recommendations are presented
and discussed. One particularly innovative element is the restructuring and use of Israel’s extensive biosafety system to
also address biosecurity goals, with minimal disruption or delay. 相似文献
469.
García Calvo T Cervelló E Jiménez R Iglesias D Moreno Murcia JA 《The Spanish journal of psychology》2010,13(2):677-684
Motivational characteristics are influential in shaping adolescents' desire to persist in sport or to discontinue their sport participation. Self-determination theory (Deci & Ryan, 2000) was utilized as the theoretical framework for this study. This theory examines whether sustained participatory involvement, defined as continued participation in the sport through the next year, was influenced by individuals' self-determined motivation and by the fulfillment of the three basic psychological needs of autonomy, competence, and relatedness. Four hundred ninety two soccer players between the ages of 13 and 17 years comprised the sample. Results indicated sport dropout was explained by higher levels of amotivation, external regulation, and introjected regulation and by lower satisfaction of relatedness and autonomy needs. The findings of this study contribute to the knowledge base on sport dropout as they supported many of self-determination theory. 相似文献
470.
The goal of this research is to describe the visual search patterns for diverse traffic signs. Twelve drivers of both genders and different driving experience levels took part in real driving research with an instrumented car provided with an eye-tracking system. Looking at signs has a weak relation with speed reduction in cases where actual driving speed was higher. Nevertheless, among the people who looked at the sign, the percentage of those who reduce the speed below the limit is greater than of those who do not look at the sign. Guide traffic signs, particularly those mounted over the road, are more frequently glanced at than speed limit signs, with a glance duration of more than one second, in sequences of more than two consecutive fixations. Implications for driving and the possibilities and limitations of eye movement analysis for traffic sign research are discussed. 相似文献