纳米级超声造影剂的哲学思考

纳米科技在医学中日益显示其重要作用。纳米科学与超声分子影像学的结合形成了超声纳米分子影像学,诞生了纳米级超声造影剂。本文借助自然辩证法和科学技术哲学的理论和观点,对纳米技术应用于超声造影剂带来的哲学思考进行剖析。纳米技术的诞生和纳米材料的发展开辟了超声分子影像学的新天地,促进超声造影剂的飞速发展。     

Spontaneous recovery of consummatory behavior, but not of consummatory successive negative contrast

Five experiments were designed to study spontaneous recovery (SR) in two situations involving consummatory behavior: consummatory successive negative contrast (cSNC) and consummatory extinction (cE). SR of consummatory suppression should occur if incentive downshift induces an egocentric memory encoding information about the emotional reaction to the downshift that is counterconditioned or extinguished during exposure to the downshifted reward. SR of cSNC failed to occur after resting periods of 24, 96, or 336 h interpolated following complete (Experiment 1) and incomplete (Experiment 2) recuperation of consummatory behavior, and was not induced by the opioid-receptor antagonist naloxone (2 mg/kg), known to enhance cSNC (Experiment 3). However, SR of consummatory behavior occurred across sessions in cSNC (Experiment 3) and cE (Experiments 4-5). Furthermore, naloxone facilitated cE without affecting SR (Experiments 4-5). These results are discussed in relation to evidence for the development of an egocentric memory of the aversive downshift experience in consummatory situations.     

Separation of conjoined twins and the principle of double effect.

This article examines the relationship between the principle of double effect and justification for separation surgeries for conjoined twins. First, the principle of double effect is examined in light of its historical context. It is argued that it can only operate under an absolutist view of good and evil that is compatible with the Bible. Given this foundation for application, scenarios for separating conjoined twins are considered against the criteria for the principle of double effect. It is concluded that the principle of double effect cannot be applied to cases wherein one of the twins must be killed. However, it is noted that this does not leave decision makers without options.     

Scaling relative incentive value in anticipatory behavior

Papini and Pellegrini (Papini, M. R., & Pellegrini, S. Scaling relative incentive value in consummatory behavior. Learning and Motivation, in press) observed that, within limits, the level of consummatory responding of rats exposed to incentive downshifts in the concentration of sucrose solutions was similar when the ratio of test/training solutions was the same. For example, 32 → 4% and 16 → 2% downshifts (1:8 test/training ratios) lead to similar levels of consummatory behavior, despite differences in the absolute concentrations of the solutions involved in the downshift. This suggests the applicability of Weber’s law to spaced-trial, incentive-downshift situations. Experiment 1 extended these results to runway performance using food pellets as reward, and Experiment 2 to lever pressing performance, using an autoshaping procedure and sucrose solutions as rewards. The results conform well to the test/training ratio suggesting that Weber’s law is applicable to anticipatory behavior. A simple mathematical rule that can be easily incorporated into models based on linear operators describes the results of consummatory and anticipatory behavior experiments.     

Testing for effects of racial attitudes and visual contrast on the speed of a driver’s response to a pedestrian

Although ethnic minorities are overrepresented in pedestrian-vehicle collisions, previous driving studies did not examine racial attitudes in such collisions. Our objective was to determine whether the speed of a driver’s response to a pedestrian was affected by the driver’s racial attitudes and the contrast between the pedestrian’s skin colour and background. Participants viewed simulated driving scenes of a pedestrian on a road and pressed a button as soon as they saw an obstacle. Visual information, but not racial attitudes, affected the time it took observers to respond to pedestrian and non-pedestrian stimuli in driving scenes. Results indicated that contrast affected response time even when the stimulus was subliminal. We believe this is the first demonstration of contrast effects with subliminal stimuli in a driving context. Results have implications for traffic safety and for methodology used to study racial attitudes.     

Feel the difference! The influence of ease experiences on the direction of social comparisons

The present work investigates if ease/difficulty experiences associated with social comparison information shape the direction of the comparison. In particular, we test the hypothesis that standards of comparison associated with experiences of ease lead to assimilation whereas standards processed under experiences of difficulty result in comparative contrast. In line with this hypothesis, we found in Experiment 1 that the easy processing of a standard led to assimilation whereas difficult processing of the same standard led to contrast. This finding was replicated in Experiment 2, even though the ease/difficulty experiences were this time introduced independently of the standard. Finally, Experiment 3 tested the boundary conditions of the influence of experiences by showing their flexible use in judgmental processes.     

社会比较：对比效应还是同化效应

社会比较直接影响人类的自我评价,对其产生两种相反的效应,即对比效应和同化效应。本文系统地回顾了社会比较的对比效应和同化效应的相关研究;并从关注自我、关注比较目标和关注自我与比较目标之间的关系三个不同方面,阐述了对社会比较效应产生调节作用的各种不同因素;最后,从一种整合和信息的视角,阐述了产生对比效应和同化效应的心理机制——选择性通达（SA）模型     

耳机传送双重听觉信号的知觉特点研究

本研究探讨了耳机以叠加法和分离法传送双重听觉信号的知觉特点.实验结果表明(1)响度感觉是听觉中枢对同一信号的双耳输入强度加工整合的结果;(2)信号间的中枢干扰作用比外周干扰作用要小.前一论点在对三维虚拟听觉显示研究中也是应十分注意的.     

Behavioral contrast: Pavlovian effects and anticipatory contrast.

Two sources of behavioral contrast have been identified previously: Pavlovian stimulus-reinforcer relations and component sequence effects (anticipatory contrast). This study sought to isolate these sources of control procedurally in a four-ply multiple schedule composed of two fixed two-component sequences. Different cues were associated with the first component of each sequence, and contrast effects were studied in these target components. In Experiment 1, differential cuing of Component 2 between sequences and availability of reinforcement during target components were varied across three groups of pigeons; the stimulus-reinforcer relation between target-component cues and schedule of reinforcement in Component 2 was varied within subjects. Control by the Pavlovian relation was demonstrated under all conditions, and anticipatory contrast was not observed. In Experiment 2, target-component duration was systematically varied in the three groups of Experiment 1. Control by the Pavlovian relation was reliably obtained only when target-component behavior was unreinforced, and diminished with increases in component duration. Anticipatory contrast emerged in the two groups for which target-component reinforcement was available. These and other data indicate that Pavlovian effects in multiple schedules may be obscured when the requisite conditions for anticipatory contrast are present.     

Inverse relations between preference and contrast

Pigeons were trained on a multiple schedule in which two target components with identical reinforcement schedules were followed by either the same-valued schedule or by extinction. Response rate increased in both target components but was higher in the target component followed by extinction, replicating previous findings of positive anticipatory contrast. A similar design was used to study negative contrast, in that the two target components were followed either by the same-valued schedule or by a higher valued schedule. Negative contrast occurred equally, on average, in both target components, thus failing to demonstrate negative contrast that is specifically anticipatory in nature. When the stimuli correlated with the two target components were paired in choice tests, the pattern of preference was in the opposite direction. For the positive contrast procedure, no significant preference between the two target stimuli was evident. But for the negative contrast procedure, preference favored the stimulus followed by the higher valued schedule. The results demonstrate a functional dissociation between positive and negative contrast in relation to stimulus value. More generally, the results demonstrate an inverse relation between response rate and preference and challenge existing accounts of contrast in terms of the concept of relative value.