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81.
Robertson  Simon 《Synthese》2010,181(1):81-106

What is the relation between what we ought to do, on the one hand, and our epistemic access to the ought-giving facts, on the other? In assessing this, it is common to distinguish ‘objective’ from ‘subjective’ oughts. Very roughly, on the objectivist conception what an agent ought to do is determined by ought-giving facts in such a way that does not depend on the agent’s beliefs about, or epistemic access to, those facts; whereas on the subjectivist conception, what an agent ought to do depends on his beliefs. This paper defends the need for, and explicates, a third category of ‘ought’: ‘warranted oughts’. Section 1 introduces the distinction between objective and subjective ‘oughts’. Sections 2–3 draw attention to some serious problems with each. Section 4 examines, though rejects, a recent attempt to replace subjective ‘oughts’ with objective ‘wide-scope oughts’ operating on belief-action combinations. Section 5 explicates the notion of a warranted ‘ought’ and defends the account against some possible objections. The resulting a picture is one in which an adequate analysis of practical normativity requires both objective and warranted ‘oughts’. Section 6 concludes by responding to a worry about countenancing both.

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Three experiments used a discriminated operant procedure to study conditional discrimination learning in rats. The first experiment showed that rats were capable of learning a biconditional discrimination in which two contexts served as conditional cues signalling the reinforcement contingencies associated with two discriminative stimuli. The discrimination was learned equally well when one discriminative stimulus signalled food, the other its absence, and when one stimulus signalled food, the other extinction plus mild footshock.

In Experiment 2 it was shown that prior training on such a conditional discrimination enhanced the subsequent context specificity of simple conditioning relative to control groups of animals for whom the prior training had not been conditional. Experiment 3 showed that a reversal of the significance of one pair of discriminative stimuli produced no spontaneous reversal in performance to a second, target, pair.

The pattern of results is best accounted for by an analysis of contextual conditional discrimination learning in terms of stimulus configurations and offers no support for the notion that rats may learn a general conditional rule or set.  相似文献   
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We examined the effects of acute psychological stress on lymphocyte proliferation and circulating levels of interleukin-1 and -2. Healthy men were exposed to two viewings of a gruesome surgery film and were asked to recall details of the film twice during a 30-min period. These subjects were compared to a nonstress control group. Lymphocyte proliferation to the mitogen concanavalin A (Con A; 5 micrograms/ml) was decreased during and after exposure to the stressor when compared to the control group. This decrease was more pronounced in subjects exhibiting greater blood pressure reactivity while viewing the film than in subjects showing smaller blood pressure responses. None of the other immunological measures was significantly affected by the stressor. Cortisol was not correlated with lymphocyte responsiveness. Possible explanations for these results and implications for further research are discussed.  相似文献   
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