The Cascade Neural Network Model and a Speed-Accuracy Trade-Off of Arm Movement

We propose a hybrid neural network model of aimed arm movements that consists of a feedforward controller and a postural controller. The cascade neural network of Kawato, Maeda, Uno, and Suzuki (1990) was employed as a computational implementation of the feedforward controller. This network computes feedforward motor commands based on a minimum torque-change criterion. If the weighting parameter of the smoothness criterion is fixed and the number of relaxation iterations is rather small, the cascade model cannot calculate the exact torque, and the hand does not reach the desired target by using the feedforward control alone. Thus, one observes an error between the final position and the desired target location. By using a fixed weighting parameter value and a limited iteration number to simulate target-directed arm movements, we found that the cascade model generated a planning time–accuracy trade-off, and a quasi–power-law type of speed–accuracy trade-off. The model provides a candidate neural mechanism to explain the stochastic variability of the time course of the feedforward motor command. Our approach also accounts for several invariant features of multijoint arm trajectories, such as roughly straight hand paths and bell-shaped speed profiles.     

动物创造创新:最简单的智慧闪光

动物创造力既有重要的生态和进化意义,也为人类创造力的研究提供了借鉴与启发。文章首先概括了近年学者们对动物创造力的定义;其次介绍了动物创造力理论的变化;重点总结了影响动物创造力的内部因素,分别是动物的探索性、新异恐惧、学习能力和坚持性,随后针对动物创造力不同脑区及相关神经递质的研究进行了展开讨论,并对动物创造力未来的研究方向进行了展望。     

注意瞬脱神经机制的研究

在很短的时间间隔内连续呈现两个目标刺激时,被试对第二个目标刺激的正确报告率显著下降,这种现象就是注意瞬脱.该文简述了注意瞬脱的概念、容量有限性等方面,尤其详细介绍了注意瞬脱神经机制研究的新进展,并对今后的研究提出展望.     

A constructive neural-network approach to modeling psychological development

This article reviews a particular computational modeling approach to the study of psychological development – that of constructive neural networks. This approach is applied to a variety of developmental domains and issues, including Piagetian tasks, shift learning, language acquisition, number comparison, habituation of visual attention, concept learning, and theory of mind. Implications of this modeling for theoretical understanding of psychological development are considered.     

工作记忆的认知模型与神经机制

本文评述了工作记忆认知模型的进展,阐述工作记忆神经机制研究的基本问题。研究者在工作记忆认知模型框架下,提出了工作记忆成分结构的脑模型。根据自己的研究探索,展望进一步的研究问题,以及TMS和fMRI/ERP等脑成像技术的结合运用对工作记忆认知神经科学研究的推动。     

A Modeling Study of Potential Sources of Curvature in Human Reaching Movements

The authors of this article suggest that the slight but consistent posture-dependent curvature of the spatial paths in the kinematic transformation between intrinsic and extrinsic coordinates may result in a systematic curvature of movements initially planned as straight-line trajectories toward the target. A kinematic planning model is presented that takes into account the anisotropy of the intrinsic and extrinsic transformation and tends to avoid movements that require excessive joint rotations by introducing slight deviations from a straight-line trajectory. Preliminary simulations showed reasonably good agreement with experimental data, especially considering that the current model is strictly based on kinematics. A quantitative analysis showed that the strategy used in the model achieves a favorable compromise between straight-line movements and angular joint changes: By slightly increasing the spatial length of the movement (i.e., by introducing curvature), an individual can greatly reduce the total amount of joint rotation required to produce the movement.     

Unmasking a shady mirror effect: Recognition of normal versus obscured faces

Hockley, Hemsworth, and Consoli (1999) Hockley, W. E., Hemsworth, D. E. and Consoli, A. 1999. Shades of the mirror effect: Recognition of faces with and without sunglasses. Memory & Cognition, 27: 128–138. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] found that following the study of normal faces, a recognition test of normal faces versus faces wearing sunglasses produced a mirror effect: The sunglasses manipulation decreased hit rates and increased false-alarm rates. The stimuli used by Hockley et al. (1999) Hockley, W. E., Hemsworth, D. E. and Consoli, A. 1999. Shades of the mirror effect: Recognition of faces with and without sunglasses. Memory & Cognition, 27: 128–138. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] consisted of separate poses of models wearing or not wearing sunglasses. In the current experiments, we separately manipulated same versus different depictions of individual faces and whether or not the faces were partially obscured. The results of a simulation and four experiments suggest that the test-based, mirror effect observed by Hockley et al. (1999) Hockley, W. E., Hemsworth, D. E. and Consoli, A. 1999. Shades of the mirror effect: Recognition of faces with and without sunglasses. Memory & Cognition, 27: 128–138. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] is actually two separable effects.     

经济决策中人际信任博弈的理论模型与脑机制

信任是指个体在缺乏足够信息来判断他人动机、意图和行为的情况下,将社会资源交给对方处置并承担相应风险的意愿。作为一种基本的社会信号机制,信任对于发展和维持良好社会关系具有重要作用。借助信任博弈范式,研究者揭示了人际信任的认知神经机制并建构了多种理论,包括背叛厌恶理论、社会规范理论、道德规范理论和默认行为模型。脑成像研究发现信任行为主要涉及内侧前额叶、尾状核、杏仁核和脑岛等脑区,其中内侧前额叶主要参与心理推理、情绪认知与调控等过程,尾状核参与同伴值得信赖性的习得与编码,杏仁核和脑岛则主要参与风险、不确定性和背叛恐惧加工。今后研究应侧重不同理论之间的补充与整合,强化不同脑区之间的功能连接与整体性,并注重信任行为中的个体差异。     

从对框架效应的分析看风险决策的神经基础

对风险决策的研究近年来一直是微观经济学和心理学的热门,但是从传统的决策理论到主张有限理性的预期理论大多是对决策行为的研究,决策的心理机制一直是无法解释的黑箱子。令人兴奋的是近几年来神经科学家及其他领域的学者开始用先进的神经心理学的方法来研究风险决策,试图理解神经过程调节风险决策行为的方式。文章从分析违背“不变性”原则的框架效应入手,从正反框架、确定选择和风险选择、风险规避和风险寻求、高估小概率事件几个方面,全面分析风险决策可能的神经基础。在总结已有研究的基础上提出了把风险决策研究扩展到不确定决策,把风险决策中的一次决策研究扩展到多次决策的研究思路     

基于GRM模型的BP神经网络参数估计

目前参数估计多采用统计方法,存在耗时长、要求被试样本容量大和项目数多等缺点。本文将BP神经网络和降维法相结合,对GRM的项目参数和考生能力参数进行估计。蒙特卡洛模拟结果显示：（1）不管是人多题少还是题多人少,该网络设计下的参数估计精度都较高;（2）可以应用到多个不同等级评分的参数估计中,甚至是超过15个等级的项目参数,估计精度也较高,这是其他参数估计方法所不可比拟的;（3）运行的时长和统计估计方法相比大大缩减。