Ecological relevance of stereopsis in one-handed ball-catching

The aim of this study was to compare one-handed catching performance between catchers with high (n = 10) and low (n = 10) binocular depth vision or stereopsis. In two sessions of 90 trials, tennis balls were projected at three different velocities towards the subject's shoulder region. Participants with good stereopsis were more successful, although the difference in number of correct catches fell short of significance. More specifically, catchers with low stereopsis made more temporal errors, but no differences in spatial errors. As the velocity of the ball increased, the initiation of the catch was delayed and catching performance decreased. The finding that stereopsis affected timing of the catch challenges the 'monocular tau hypothesis' in the control of interceptive timing, while the velocity effect shows that the act of catching a ball is not initiated at a constant time-to-contact.     

Sexuality attitudes and behaviors of self-described very religious urban students in middle school

Data from a survey of 869 students aged 11 to 15 years and attending six urban middle schools were analyzed to identify differences in sex attitudes and behaviors between self-reported very religious students and their less religious peers. The two groups were demographically similar. They differed on only two attitude items, one suggesting that intercourse was a normal part of teenage dating and the other suggesting intercourse was alright if the two people were in love. The groups did not differ in their estimation of their peers' sexual activity or attitude or in terms of their own intercourse behavior or future intentions.     

What is the speed to transparent and kinetic-boundary displays?

To compare transparent motion and kinetic boundaries with unidirectional motion, in many studies the relative motion is generated by superimposing or adjoining unidirectional motions oriented in opposite directions. The presumption, tacitly underlying this comparison, is that the two oppositely directed velocities are independent of one another as far as their speed is concerned, i.e. the speed of the relative motion is presumed to be equivalent to the speed of the unidirectional components. Here we report that the relative motion between dots moving in opposite directions augments perceived speed. A constant-stimuli procedure was used to pair transparent-motion or kinetic-boundary displays with unidirectional motion, and human observers were asked to match the speed of the relative and unidirectional motions. The results show that transparency and kinetic boundaries increase the perceived visual speed by about 50%, compared with the speed of the individual components.     

Nonstrategic subjective threshold effects in phonemic masking

Three backward-masking experiments demonstrated that the magnitude of the phonemic mask reduction effect (MRE) is a function of subjective threshold and that the magnitude is also independent of stimulus-based response strategies. In all three experiments, a target word (e.g., bake) was backward masked by a graphemically similar nonword (e.g., BAWK), a phonemically similar nonword (e.g., BAIK), or an unrelated control (e.g., CRUG). Experiments 1 and 2 had a low percentage (9%) of trials with phonemic masks and differed only in baseline identification rate. Experiment 3 controlled baseline identification rate at below and above subjective threshold levels, with 9% phonemic trials. The results were that identification rates were higher with phonemic masks than with graphemic masks, irrespective of the low percentage of phonemic trials. However, the magnitude of the phonemic MRE became large only when the baseline identification rate was below subjective threshold. The pattern of the phonemic MRE was interpreted as a result of rapid automatic phonological activation, independent of stimulus-based processing strategies.     

Time course of word identification and semantic integration in spoken language

The minimum duration signal necessary to identify a set of spoken words was established by the gating technique; most words could be identified before their acoustic offset. Gated words were used as congruous and incongruous sentence completions, and isolation points established in the gating experiment were compared with the time course of semantic integration evident in event-related brain potentials. Differential N400 responses to contextually appropriate and inappropriate words were observed about 200 ms before the isolation point. Semantic processing was evident before the acoustic signal was sufficient to identify the words uniquely. Results indicate that semantic integration can begin to operate with only partial, incomplete information about word identity. Influences of semantic constraint, word frequency, and rate of presentation are described.     

人类同等性和文化多样性

全人类有什么普遍之处？怎样把他们区别开？在考察这两个问题时,可以根据类型分成三个阶段：柏拉图式的论述、浪漫主义的对比法和当代的综合,最后是在当今的人类生物学和语言学中被推进和发展了的假说。一、柏拉图式的论述柏拉图式的论述中经常被引证的章句,不是见于柏拉图而是他的学生亚里士多德的著作中。在一本早期的小册子《论解释》的开头这样写道：全人类的书写标记是不相同的,他们的有声语言也是不相同的。但它们首先都是灵魂的情感符号,在这一点上全都是一样的;这些情感具有的事物相似性也是相同的。这说明人们所关心的都是相…     

Intercepting Moving Objects During Self-Motion

It is generally assumed that in catching a fly ball, an efficient strategy for dealing with the horizontal component of the ball's trajectory is for the observer to keep the angular position of the ball constant with respect to his head. That strategy is called the constant bearing angle or CBA strategy. Maintenance of angular constancy results in the simultaneous arrival of both observer and ball at the landing spot. The authors analyzed the approach behavior of 26 subjects in a ball-interception task with straight paths for both the subjects and the ball. Subjects moved at a velocity that maintained a close-to-constant horizontal angular position of the ball with respect to the end effector throughout the approach phase rather than a constant bearing angle with respect to their head. Velocity adaptations occurred as a function of the changes in the angular velocity of the ball in such a way that a positive or negative angular velocity was canceled. Thus, an actor following the CBA strategy does not need to know where and when the ball will arrive (i.e., a predictive strategy), because reliance on the CBA strategy ensures that he will make the appropriate adaptations that enable him to arrive at the right place in the right time.     

社会主义生产关系的表现形式

一、社会主义生产关系的物化生产、分配、交换、消费以及经济关系的所有不同形态在实践中差不多总是表现为物的关系。生产关系直接或间接地同物发生联系。人生活和活动在物质世界中,与他人有密不可分的联系。但是,这种同他人的联系,在很大程度上是通过物表现出来的。一些人生产产品,而另一些人则消费产品。随着社会分工的发展,这种某一个人生产的产品被另一个人用于生产或者个人的消费的情况,正在越来越普遍。反之,每一个人消费的并不是他所生产的。一个人生产的物被另一个人所消费。物不仅应该通过生产过程,而且在进入消费之前还要通过分配和交换的过程。因此,在生产