Analytic model for the line tension of a bowing dislocation segment

The resistance of a dislocation to bowing under stress governs the strength of the gamut of metallic material systems. This resistance is commonly referred to as the dislocation line tension (Γ) and is employed ubiquitously within continuum scale models of metal plasticity. Despite its significance, a unifying model for the line tension of a bowing dislocation segment, which has been analytically derived and independently reproduces simulation results, remains lacking. Here, we report a model for Γ of a curved, semicircular bowing dislocation segment. Upon applying our model to the operative stress of a Frank–Read dislocation source, we predict a prelogarithmic scaling of the Frank–Read source strength in agreement with existing simulation results. Moreover, in the limit of infinitesimal bowout we predict a prelogarithmic line tension factor which also agrees with theoretical analyses. Our model provides insight into the evolution of an arbitrarily oriented, stressed dislocation segment without resorting to numerical methods.     

线条朝向的空间构型对视觉工作记忆表征的影响

采用行为实验和事件相关电位技术(ERP),通过整体检测的变化觉察范式,探讨线条朝向的空间构型对视觉工作记忆表征的影响及机制。行为结果发现,水平排列线条朝向的视觉工作记忆成绩高于杂乱排列; 水平排列线条朝向有框时的视觉工作记忆成绩低于无框条件; ERP结果发现,无框条件下水平排列的线条朝向诱发的对侧延迟活动的波幅小于有框条件。以上结果说明,水平排列的空间构型能够促进线条朝向的视觉工作记忆表征,这一促进作用的潜在机制可能是水平排列的空间构型能够降低信息表征的负荷。     

空间-时间联合编码效应：来自手动和眼动证据

本研究探讨汉语背景下不同反应方式（手动,眼动）、不同方位（水平,垂直）上空间-时间联合编码效应（STEARC效应）存在的可能性。四个实验均采用两类时间词语诱发被试的时间表征,采用2（时间：过去、将来）×2（反应手/眼跳方向：左、右/上、下）的被试内设计。结果表明汉语背景下的人们将过去和身体左边（上）联系在一起,把将来和右边（下）联系在一起,人们存在自左向右和自上而下的STEARC效应,这种效应不存在手动和眼动的分离,人们对时间的表征不仅是一条时间线,更是一个心理时间地图。     

工作记忆在时间和空间心理联结中的调节作用*

探讨时间的空间表征是否受到工作记忆的调节。实验将时间比较任务和工作记忆中的延迟匹配范式相结合。结果发现,记忆匹配条件下,刺激的空间位置不影响时间判断,而记忆不匹配条件下,当左侧刺激呈现的时间短,右侧刺激呈现的时间长时,时间判断的反应时更短。结果表明,时间的空间表征具有灵活性,受到工作记忆的调节。     

Arabic digit naming speed: task context and redundancy gain

There is evidence for both semantic and asemantic routes for naming Arabic digits, but neuropsychological dissociations suggest that number-fact retrieval (2x3=6) can inhibit the semantic route for digit naming. Here, we tested the hypothesis that such inhibition should slow digit naming, based on the principle that reduced access to multiple routes would counteract redundancy gain (the response time advantage expected from parallel retrieval pathways). Participants named two single digit numbers and then performed simple addition or magnitude comparison (Experiment 1), multiplication or magnitude comparison (Experiment 2), and multiplication or subtraction (Experiment 3) on the same or on a different pair of digits. Addition and multiplication were expected to inhibit the semantic route, whereas comparison and subtraction should enable the semantic route. Digit naming time was approximately 15ms slower when participants subsequently performed addition or multiplication relative to comparison or subtraction, regardless of whether or not the same digit pair was involved. A letter naming control condition in Experiment 3 demonstrated that the effect was specific to digit naming. Number fact retrieval apparently can inhibit Arabic digit naming processes.     

Flexible spatial mapping of different notations of numbers in Chinese readers

The spatial component of numerical and ordinal information has been explored in previous research. However, how such mapping emerges and how it is affected by the learning experience are issues still under debate. In the current study, we examined the orientation of the mental number line for different numerical notations (e.g., “1”, “—-”, “”) in Chinese readers. Our data demonstrated that Arabic numbers are mentally aligned horizontally with a left-to-right directionality, while Chinese number words are aligned vertically with a top-to-bottom directionality. These findings indicate that different notations of the same concept have flexible mappings within space, which is plausibly shaped by the dominant context in which the numerical notations appear.     

Representational change and magnitude estimation: why young children can make more accurate salary comparisons than adults

Development of estimation has been ascribed to two sources: (1) a change from logarithmic to linear representations of number and (2) development of general mathematical skills. To test the representational change hypothesis, we gave children and adults a task in which an automatic, linear representation is less adaptive than the logarithmic representation: estimating the value of salaries given in fractional notation. The representational change hypothesis generated the surprising (and accurate) prediction that when estimating the magnitude of salaries given in fractional notation, young children would outperform adults, whereas when estimating the magnitude of the same salaries given in decimal notation, adults would outperform children.