Relative and absolute density of reinforcement as factors influencing the peak shift

Four groups of six pigeons each were given nondifferential training on multiple variable-interval variable-interval reinforcement schedules and then were switched to differential training involving a multiple schedule in which reinforcement density was reduced in one of the two components. The multiple schedules used in the four groups had mean interreinforcement intervals of 1 min and 1 min in the two components changed to 1 min, 5 min; 2.5 min, 2.5 min changed to 2.5 min, 5 min; 12 sec, 12 sec changed to 12 sec, 24 sec; and 12 sec, 12 sec changed to 12 sec, 60 sec. In subsequently administered wavelength generalization tests, some peak shifts were observed in each condition and occurred occasionally in the absence of behavioral contrast or rate reduction in the less-reinforced component. The best predictor of peak shift was a high proportion of total responses emitted during the more-reinforced component at the end of differential training.     

Stress concentration and crack nucleation at the end of a low-angle tilt boundary

A low-angle tilt boundary (LATB) is easily sheared by dislocations identical to those constituting the boundary. This shear results in the creation of semi-infinite low-angle tilt boundaries, which generate a stress at their tips large enough to cause fracture.     

Personal space and density as factors in task performance and feeling of crowding.

The study was an investigation of the effects of density and personal space on simple and complex task performance and on feelings of crowding on 60 female Hindu students in India. A 2 x 2 design was used. Density was manipulated by varying the number of subjects in a fixed room space (social density), and the stop-distance technique was used to measure personal space. Results revealed that complex task performance was adversely affected by a high-density condition and by the personal space of the subjects, leading to a significant interaction effect of the two variables, but no significant main or interaction effect was found for the simple task performance. The subjects with "far" personal space under the high-density condition evaluated the environment of the experimental room as most crowded, more than any other subject did.     

The calibration of neutral density wedges

A method for calibrating neutral-density filters is described.     

数量认知和密度认知的关系

数量和密度认知的关系是数量认知研究的关键问题。相关研究在三个方面存在不足：首先, 先前实验研究缺乏对两种加工的有效操控和区分; 其次, 现有理论或认为“数量和密度加工完全独立”, 或认为“数量加工是对密度进行推论的结果”, 比较片面; 第三, 已有理论模型抽象, 不重视功能模块的解释。基于数量认知的多阶段加工特点, 未来研究可以讨论数量认知进行基于密度认知的整合加工的可能性, 提出整合数量和密度加工的理论构想。     

The effect of density and diameter on haptic perception of rod length

Three experiments on the effect of density and diameter on haptic perception of rod length are reported. In Experiment 1, the subjects wielded visually occluded rods of different densities. Perceived length was found to be affected by the density of the rod regardless of the actual length. In Experiment 2, three aluminum rods of different lengths with handles of four different diameters were wielded. Perceived length of the rod was found to be shorter as the diameter of the handle with which it was wielded increased. A diameter—length illusion was thereby produced. In Experiment 3, visually occluded rods of different diameters but of the same moment of inertia about thex-axis were wielded with the right hand, and tubes of different diameters were felt with the left hand. The subjects were instructed that their right hand was grasping a handle, and that the actual diameter of the rod could be felt with the left hand. Rods were perceived to be shorter if a larger diameter was felt with the left hand. The results showed that perceived length is not just a function of actual rod length, and that it is not accounted for by inertia only. The results are further discussed in terms of the nature of invariants and the effect of knowledge on perception.     

McGurk效应的影响因素与神经基础

McGurk效应(麦格克效应)是典型的视听整合现象, 该效应受到刺激的物理特征、注意分配、个体视听信息依赖程度、视听整合能力、语言文化差异的影响。引发McGurk效应的关键视觉信息主要来自说话者的嘴部区域。产生McGurk效应的认知过程包含早期的视听整合(与颞上皮层有关)以及晚期的视听不一致冲突(与额下皮层有关)。未来研究应关注面孔社会信息对McGurk效应的影响, McGurk效应中单通道信息加工与视听整合的关系, 结合计算模型探讨其认知神经机制等。     

The influence of neighborhood density on phonetic categorization in aphasia

The present study examined the contribution of lexically based sources of information to acoustic-phonetic processing in fluent and nonfluent aphasic subjects and age-matched normals. To this end, two phonetic identification experiments were conducted which required subjects to label syllable-initial bilabial stop consonants varying along a VOT continuum as either /b/ or /p/. Factors that were controlled included the lexical status (word/nonword) and neighborhood density values corresponding to the two possible syllable interpretations in each set of stimuli. Findings indicated that all subject groups were influenced by both lexical status and neighborhood density in making phonetic categorizations. Results are discussed with respect to theories of acoustic-phonetic perception and lexical access in normal and aphasic populations.     

The relationship between external variables and common factors

A theorem is presented which gives the range of possible correlations between a common factor and an external variable (i.e., a variable not included in the test battery factor analyzed). Analogous expressions for component (and regression component) theory are also derived. Some situations involving external correlations are then discussed which dramatize the theoretical differences between components and common factors.Support by the National Research Council of Canada (NRC Grant No. A4640) and the University of British Columbia (UBC Humanities and Social Sciences Grant 26-9718) is gratefully acknowledged.This paper is based in part on the author's Ph.D. dissertation. I am particularly grateful to my dissertation advisor, Dr. Peter H. Schönemann. Thanks also to the editor and the anonymous reviewers, who contributed many helpful comments and suggestions.     

Perception of spatial and social density

The effects of family size on the perception of three abstract rooms that differed in social and spatial density were studied. The rooms were rated on the dimensions, evaluation, spirituality, activity, and aesthetic appeal. Of the 48 subjects half were from large families with six or more members, and half were from smaller families. Family size had no effect on the perception of the rooms. The room low in spatial density was perceived most favorably, and there was no difference in the perception of a room high in social density and one high in spatial density.     

视觉表象生成系统及其影响因素

视觉表象是在记忆基础上产生的类似知觉的信息表征, 也是人们在日常生活中不可或缺的心理活动之一。本综述介绍了该领域中比较有影响力的表象计算理论模型, 并进一步归纳了视觉表象生成系统的成分及其对应的神经基础。分析结果强调了初级视觉皮层作为“视觉缓冲器”是生成表象的主要机能结构, 以“视觉缓冲器”为基础的表象生成系统的机能受多重因素影响。本综述有助于对视觉表象生成系统形成全面的认识, 促进视觉表象实质的进一步研究。     

The interaction of internal and external factors in producing psychopathology

When we treat or discuss child patients who have been referred to us for help with a wide variety of mainly neurotic disturbances we usually take it for granted that a host of factors, both internal and external, have combined and contributed to produce the clinical picture presented by any child at the time of referral. But although it is the endeavour of every diagnostician and of every therapist to tease out, either at the diagnostic stage or in the course of the ongoing treatment, the multiple pathogenic factors which were responsible in bringing about a particular disturbance, every diagnostician and clinician knows only too well from his experiences what an intricate and difficult task this is. This is due both to the complexity in the functioning of the mental apparatus and to our lack of sufficient knowledge of the internal effects of a developing child's earliest experiences.