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41.
If a group of foragers distributes among resource patches according to the ideal free distribution, the relative number of foragers in each patch should match the relative amount of resource obtained there, unless deviations arise from factors such as incomplete information or interforager interference. In analogy to individual choice, such effects may produce undermatching—group distribution falling short of resource distribution—or overmatching—group distribution overshooting resource distribution. In the present experiments, a flock of about 30 pigeons distributed between two patches with continuous inputs of green peas. Competition was varied by changing the size or extent of the patches. When the patches were areas or troughs, some undermatching occurred. When the patches were small bowls, strong undermatching occurred. When travel was required to switch patches, undermatching decreased slightly. A visual barrier that prevented pigeons from seeing one patch from the other had no effect. Overall rate of food delivery, varied over a wide range, had no effect. It appeared that the mechanism of flock distribution depended on comparisons between patches that were successive rather than simultaneous. Although most pigeons participated in the experiments, and different pigeons participated to different extents, individual pigeons tended to be consistent in the extent of participation from session to session, suggesting the possibility that participation might reflect competitive ability. Examination of the preferences and switching of individual pigeons revealed no consistency within or across individuals. It appeared that the flock's distribution was a truly emergent phenomenon, in the sense that results at the level of the flock in no way paralleled behavior at the level of the individual. 相似文献
42.
The ideal free distribution theory (Fretwell & Lucas, 1970) predicts that the ratio of foragers at two patches will equal the ratio of food resources obtained at the two patches. The theory assumes that foragers have \"perfect knowledge\" of patch profitability and that patch choice maximizes fitness. How foragers assess patch profitability has been debated extensively. One assessment strategy may be the use of past experience with a patch. Under stable environmental conditions, this strategy enhances fitness. However, in a highly unpredictable environment, past experience may provide inaccurate information about current conditions. Thus, in a nonstable environment, a strategy that allows rapid adjustment to present circumstances may be more beneficial. Evidence for this type of strategy has been found in individual choice. In the present experiments, a flock of pigeons foraged at two patches for food items and demonstrated results similar to those found in individual choice. Experiment 1 utilized predictable and unpredictable sequences of resource ratios presented across days or within a single session. Current foraging decisions depended on past experience, but that dependence diminished when the current foraging environment became more unpredictable. Experiment 2 repeated Experiment I with a different flock of pigeons under more controlled circumstances in an indoor coop and produced similar results. 相似文献
43.
Increases in regulatory oversight of animal research require verification of effects of standard practices. There are no formal guidelines for establishing free-feeding weights in adult pigeons. In the present study, pigeons were obtained from a commercial supplier, weighed upon arrival, and then held in quarantine for 7 days with free access to food. Subsequently, still with continuous access to food, they were weighed daily for 30 days. No significant changes in weights occurred over the 30-day period for male pigeons, indicating that seven days is sufficient for establishing a baseline body weight. A secondary finding of higher day-to-day variability in the weights of female pigeons may serve as a method of sexing pigeons. 相似文献
44.
Ursula Goodenough 《Zygon》2005,40(2):369-380
Abstract. Despite its rich and deepening panoply of empirical support, evolutionary theory continues to generate widespread concern. Some of this concern can be attributed to misunderstandings of the original concept, some to unfamiliarity with its current trajectories, and some to strongly held fears that it strips the human of cherished attributes. In this essay I seek to deconstruct such misunderstandings, lift up current concepts of what evolution entails, and address some of the existential issues it generates. 相似文献
45.
Richard Double 《Metaphilosophy》2003,34(4):510-523
Abstract: In this article I consider when the question of whether entities exist subjectively (only in the minds of subjects) or objectively (in themselves, independently of the minds of subjects) is important, both theoretically and practically. I argue that when it comes to the metaphysics underlying three types of moral questions, broadly conceived, the subjectivity question does not matter practically, although it is widely thought to matter. Subjectivism does not matter in these moral questions in the same way(s) it matters in some nonmoral metaphysical issues. The moral questions I consider are the meaning of life, normative ethics, and the free‐will problem. The nonmoral issues I address are the existence of God, the traditional mind/body problem, and personal identity. I explain the difference by noting that certain metaphysical issues on the fact side of the fact/value distinction impinge on persons' lives more prominently than do the metaphysics behind the three moral questions. 相似文献
46.
Gregory P. Hanley Jeffrey H. Tiger Einar T. Ingvarsson Anthony P. Cammilleri 《Journal of applied behavior analysis》2009,42(1):33-41
The present study evaluated the effects of classwide satiation and embedded reinforcement procedures on preschoolers' activity preferences during scheduled free‐play periods. The goal of the study was to increase time allocation to originally nonpreferred, but important, activities (instructional zone, library, and science) while continuing to provide access to all free‐play activities. The satiation intervention applied to preferred activities resulted in increased time allocation to the instructional and science activities, the customized embedded reinforcement interventions resulted in increased time allocation to all three target activities, and high levels of attendance to the instructional and library activities were maintained during follow‐up observations. Implications for the design of preschool free‐play periods are discussed. 相似文献
47.
Elizabeth J. Marsh 《Current directions in psychological science》2007,16(1):16-20
ABSTRACT— In contrast to laboratory free recall (which emphasizes detailed and accurate remembering), conversational retellings depend upon the speaker's goals, the audience, and the social context more generally. Because memories are frequently retrieved in social contexts, retellings of events are often incomplete or distorted, with consequences for later memory. Selective rehearsal contributes to the memory effects, as does the schema activated during retelling. Retellings can be linked to memory errors observed in domains such as eyewitness testimony and flashbulb memories; in all of these situations, people retell events rather than engage in verbatim remembering. 相似文献
48.
Henry P. Stapp 《Zygon》2006,41(3):599-616
Abstract. René Descartes proposed an interactive dualism that posits an interaction between the mind of a human being and some of the matter in his or her brain. However, the classical physical theories that reigned during the eighteenth and nineteenth centuries are based exclusively on the material/physical part of Descartes' ontology, and they purport to give, in principle, a completely deterministic account of the physically described properties of nature, expressed exclusively in terms of these physically described properties themselves. Orthodox contemporary physical theory violates this condition in two separate ways. First, it injects random elements into the dynamics. Second, it requires psychophysical events, called Process 1 interventions by John von Neumann. Neither the content nor the timing of these events is determined, even statistically, by any known law. Orthodox quantum mechanics considers these events to be instigated by choices made by conscious agents. This quantum conception of the mind‐brain connection allows many psychological and neuropsychological findings associated with the apparent physical effectiveness of our conscious volitional efforts to be explained in a causal and practically useful way. According to this quantum approach, conscious human beings are invested with degrees of freedom denied to the mechanistic automatons to which classical physics reduced us. 相似文献
49.
Atomic force microscopy of dislocation etch pit structures is a convenient means of characterising the dislocation structure in etchable materials at high resolution for dislocation spacing extending down to 25 nm . This is demonstrated for single crystals of CaF2. The local deformation zone generated around nanoindents at ambient temperature and the low-angle boundaries generated in the bulk during uniaxial compression at elevated temperatures are presented as examples. 相似文献
50.
David Humbert 《The Journal of religious ethics》2014,42(2):310-333
In his influential book After Virtue, Alasdair MacIntyre identifies Kierkegaard's view of ethics with that of Kant. Both Kant and Kierkegaard, according to MacIntyre, accept the modern paradigm of moral activity for which freedom of the will is the ultimate basis. Ronald M. Green, in Kierkegaard and Kant: The Hidden Debt, accepts and deepens this alignment between the two thinkers. Green argues that Kierkegaard deliberately obscured his debt to Kant by a systematic “misattribution” of his ideas to other thinkers, and to classical philosophy in particular. This essay argues that MacIntyre and Green are mistaken in identifying Kierkegaard with the Kantian tradition of moral autonomy and that they overlook his debt to the classical conception of virtue. In casting Kierkegaard in the role of the quintessential exponent of a modern conception of freedom, they have perhaps overlooked one of the greatest critics of moral autonomy who has ever lived. 相似文献