The effects of differing response-force requirements on fixed-ratio responding of rats.

Rats were exposed to two-component multiple schedules of food delivery. In the first experiment, 15 responses were required to produce food in both components. A downward force of 0.25 N (25 g) was always required to operate the response lever in one component. In the other, the required force was 0.25, 0.50, 1.00, or 2.00 N (25, 50, 100, or 200 g). In the second experiment, 0.25 N of force operated the lever in one component, but in the other, the force requirement for five consecutive responses at the beginning, middle, or end of each ratio was increased from 0.25 to 2.00 N. In the third experiment, the number of responses required to produce food was reduced from 15 to 5, and then to 1. Again, the effects of altering response force from 0.25 to 2.00 N were examined. In general, as response force increased in all experiments, mean response rates decreased and mean interresponse times increased.     

Effects of room tilting on body sway: Adaptation and strategies for maintaining a standing posture

The purpose of this study was to examine the effects of a tilting room on body sway across a series of trials. Sixteen subjects were instructed to maintain an upright position in the tilting room, and their body sway was measured by a force plate. After the experimental session, subjects were interviewed about awareness, strategies and impressions. The results indicated that the forward-tilting room induced forward body sway, as would a moving room. The center of gravity in the pre-tilting period in the first trial was significantly more forward than in the following trials. From the analysis of strategy, subjects were divided into two groups: maintaining-standing strategy group and other-strategies group. While subjects who used the maintaining-standing strategy swayed more in the first trial, they had significantly reduced their body sway compared with the other group by the ninth and tenth trials. Based on these results, the effects of a moving room for adult subjects as related to the context-dependent weighting of new inputs are discussed.     

Switching from competition to sharing or cooperation at large response requirements: competition requires more responding

Two pairs of high-school students matched-to-sample for money. On each trial, a subject could either respond on one lever to take the matching-to-sample problem himself (taking response) or respond on a second lever to give the problem to his coactor (giving response). The first subject to complete the response requirement determined the distribution of the problem. Competition maximizes the amount of responding over trials, i.e., both subjects make taking responses on each trial. Sharing and cooperation minimize responding: only one subject makes a taking response (sharing) or a giving response (cooperation) on each trial, and the subjects alternate responding such that there is an equitable distribution of responses and reinforcers over trials. Large increases in the fixed-ratio response requirement to distribute problems produced: (1) a switch from competition to sharing or cooperation, (2) the expected concomitant change from inequitable to equitable distributions of reinforcers, and (3) a reduction in the amount of responding for three of the four subjects. Previous animal research has shown that large response requirements may have aversive properties. Switching from competition to sharing or cooperation at large response requirements allows a reduction in responding and, at the same time, a moderate number of reinforcers for each subject.     

Of Power and Compassion

Abstract: While military and economic power are obviously central instruments of policy in international relations, there are a number of reasons why power alone is insufficient to succeed in fighting terrorism. Three central reasons are discussed in this essay: the limitations and the dilemma of power; the proposition that the most threatening form of terrorism, such as al‐Qaeda's, is conducted by nonstate actors, conventional deterrence against whom is less effective; and the role of motivation in conflicts where the distribution of power is asymmetrical. In addition to these objective reasons, it is argued that the foreign‐policy strategies pursued ultimately affect the actors' own values.     

学前儿童朴素生物学研究新进展:活力因果机制及其应用

学前儿童倾向于采用活力因果机制,即用生命力的交换和获取来解释与机体有关的生命现象.活力因果解释介于意图因果解释和机制因果解释之间,被认为是专属于生物领域的一种因果认知机制,它的提出为存在独立的朴素生物学理论提供了强有力的证据.4到6岁是活力机制发展的关键时期.同时,在年长儿童和成人对机体生命现象的认识中,这一机制继续发挥着作用,并不会随着儿童年龄的增长被其它因果机制完全取代.探讨可能导致活力因果机制发展差异性的影响因素以及它与其它因果机制的共同作用将是未来研究的方向.     

Control of oscillatory force tasks: Low-frequency oscillations in force and muscle activity

Force variability during steady force tasks is strongly related to low-frequency oscillations (<0.25 Hz) in force. However, it is unknown whether low-frequency oscillations also contribute to the variability of oscillatory force tasks. To address this, twelve healthy young participants (21.08 ± 2.99 years, 6 females) performed a sinusoidal force task at 15% MVC at two different frequencies (0.5 and 1 Hz) with isometric abduction of the index finger. We recorded the force from the index finger and surface EMG from the first dorsal interosseous muscle and quantified the following outcomes: 1) trajectory variability and accuracy; 2) power spectrum of force and EMG bursting below 2 Hz; 3) power spectrum of the interference EMG from 4 to 60 Hz. The trajectory variability and error significantly increased from 0.5 to 1 Hz task (P < 0.01). Increased force oscillations <0.25 Hz contributed to greater trajectory variability and error for both the 0.5 and 1 Hz oscillatory task (R² > 0.33; P < 0.05). The <0.25 Hz oscillations in force were positively associated with greater power in the <0.25 Hz for EMG bursting (R² > 0.52; P < 0.01). The modulation of the interference EMG from 35 to 60 Hz was a good predictor of the <0.25 Hz force oscillations for both the 0.5 Hz task and 1 Hz task (R² > 0.66; P < 0.01). These results provide novel evidence that, similar to steady contractions, low-frequency oscillations of the motor neuron pool appear to be a significant mechanism that controls force during oscillatory force tasks.     

物体受力分析正误样例组合的学习效果

分别采用正误样例组合、有无错误标记的正误样例组合和有标记的正误样例配对组合设计方法,以物体受力分析正误样例为实验材料,以初中三年级学生为被试进行3项实验,考察了被试物体受力分析图正误样例组合的学习效果。结果表明,正误样例组合的学习成绩显著优于正确样例组合的学习成绩;有标记的正误样例组合的学习成绩显著优于无标记样例组合的学习成绩;有标记正误样例配对组合的学习成绩明显优于正确样例组合的学习成绩。     

Problems for virtue theories in epistemology

This paper identifies and criticizes certain fundamental commitments of virtue theories in epistemology. A basic question for virtues approaches is whether they represent a ‘third force’––a different source of normativity to internalism and externalism. Virtues approaches so-conceived are opposed. It is argued that virtues theories offer us nothing that can unify the internalist and externalist sub-components of their preferred success-state. Claims that character can unify a virtues-based axiology are overturned. Problems with the pluralism of virtues theories are identified––problems with pluralism and the nature of the self; and problems with pluralism and the goals of epistemology. Moral objections to virtue theory are identified––specifically, both the idea that there can be a radical axiological priority to character and the anti-enlightenment tendencies in virtues approaches. Finally, some strengths to virtue theory are conceded, while the role of epistemic luck is identified as an important topic for future work.