视觉预期和注意指向对姿势和动作肌肉预期和补偿姿势调节的影响

采用经典落球试验研究范式,同步观察视觉预期和注意指向对腰部姿势肌肉和上肢运动肌肉预期和补偿姿势调节的影响,探索视觉预期和注意指向影响姿势控制的早期心理生理机制。24名青年志愿者(10名男性,14名女性)参与完成本实验,分别在有、无视觉预期以及注意指向"托盘稳定"或者"重心稳定"的实验条件下观察外部姿势干扰对腰部姿势肌肉(L5~S1腰部多裂肌)和上肢动作肌肉(肱二头肌)预期姿势调节(anticipatory postural adjustments,APAs)和补偿姿势调节(compensatory postural adjustments,CPAs)相关时间和强度参数的影响。APAs和CPAs的时间和强度参数通过获取被检肌肉s EMG信号并参照相关检测规范进行。结果显示:(1)视觉预期对多裂肌的APAs启动时间,对肱二头肌的APAs启动时间、APAs强度和CPAs强度有显著影响;(2)注意指向对多裂肌的CPAs启动时间和肱二头肌APAs启动时间有显著影响;(3)视觉预期和注意指向对肱二头肌的APAs启动时间和APAs强度有交互作用。研究认为,突发外部姿势干扰条件下姿势肌肉和动作肌肉的姿势调节策略具有一定的差异,视觉预期和注意指向仅对姿势肌肉的时间参数有影响,对动作肌肉APAs和CPAs时间和强度参数都产生调节作用,表明在中枢神经系统的姿势控制中,人体姿势策略的调节是通过对姿势肌肉和动作肌肉的双重控制来完成的,视觉预期效应和心理指向效应反映在对不同功能肌肉前馈控制和反馈控制相应参数的调节。     

姿势干扰强度的心理预期效应

本研究基于经典快速举臂试验与落球试验范式, 采用表面肌电信号分析技术, 研究内、外姿势干扰强度的心理预期对腰部姿势肌肉和上肢动作肌肉预期姿势调节(APAs)和补偿姿势调节(CPAs)的影响, 探讨中枢神经系统(CNS)对内、外姿势干扰的控制策略。20名健康受试者先后完成不同负荷强度的快速举臂试验和落球试验, 同步采集腰部竖脊肌、腰部多裂肌和上肢肱二头肌的表面肌电信号, 计算肌肉预激活时间和APAs与CPAs积分肌电值, 观察内、外姿势干扰强度的心理预期对中枢APAs和CPAs控制机制的影响。结果显示内部姿势干扰条件下, 干扰强度的心理预期对腰部多裂肌、腰部竖脊肌和上肢肱二头肌的APAs强度有显著影响, 而对预激活时间和CPAs强度无显著影响; 外部姿势干扰条件下, 干扰强度的心理预期对腰部多裂肌、腰部竖脊肌和肱二头肌的APAs强度有显著影响, 对肱二头肌和腰部多裂肌预激活时间有显著影响, 而对CPAs强度无显著影响。突发可预期姿势干扰条件下姿势的快速反应是一个由CNS主导的神经肌肉运动控制过程。受姿势干扰强度心理预期的影响, CNS对内、外突发姿势干扰条件下腰部姿势肌肉的活动采取了不同的控制策略。在内部姿势干扰条件下, 干扰刺激发生时间明确, CNS主要通过对APAs强度的调节来实现姿势肌肉的优化控制; 而在外部姿势干扰条件下, 干扰刺激时间不明确, CNS则通过对局部稳定肌APAs预激活时间以及局部稳定肌和整体稳定肌APAs强度的双重调节实现姿势肌肉的优化控制。干扰强度的心理预期对姿势肌肉APAs和CPAs的作用表明, 心理预期效应主要源自于CNS对局部和整体稳定肌APAs控制机制的调制。     

线索起点模糊水平和注视时间对汉字知觉干扰效应的影响

采用经高斯模糊技术处理的汉字,以辨认为任务,实验一考察了线索起点模糊水平和注视时间、实验二考察了线索注视时间和刺激辨认时间对知觉干扰效应的影响.结果发现:1.线索起点模糊水平的增加对汉字知觉干扰效应存在显著的影响;2.超越激活水平的最低阈值之后,线索注视时间的延长(1、2、4、6秒)不再影响知觉干扰效应;3.刺激辨认时间的延长(2、4、6秒)对知觉干扰效应影响不大.这些结果都倾向于支持失匹配假说.     

眼睛注视的知觉及其线索效应

对眼睛注视知觉、眼睛注视线索效应及其影响因素等相关研究进行了总结和分析。结果发现:(1)婴儿从一出生就对眼睛注视线索表现出强烈的敏感性,眼睛注视知觉对语言和社会等能力的发展有很大影响;(2)颞上沟是加工眼睛注视线索的特异神经结构,它与实时监控情绪和情感的杏仁核存在神经联结,成为社会认知神经系统的重要组成部分;(3)对眼睛注视线索的早期加工显示出特异的脑电活动模式;(4)眼睛注视线索效应与外周线索的反射式效应相类似,但持续时间较长;(5)眼睛注视线索效应不仅受面部结构信息的影响,也受自上而下加工等高水平认知因素的调节,并显示出明显的个体差异。对眼睛注视线索效应的进一步研究应涉及人格判断、喜好评价和心理理论等高级社会认知活动。     

基于汉字搜索的情景线索效应研究

个体通过学习目标−场景联结关系提高搜索速度的现象即为情景线索效应。本研究以高频（包含丰富语义线索）或低频（语义线索少）汉字为实验材料考察语义、字形特征、空间位置线索的作用。结果显示个体可以学习字集−位置重复场景产生情景线索效应,且该效应在改变高频字集的空间线索而非字集线索或改变低频字集线索而非空间线索时可迁移,表明在情景线索学习中,语义线索占据优先地位,其次是空间线索,最后是字形特征线索。     

即刻学习判断的系列位置效应：内外部线索的影响

为了检验即刻学习判断对内外部线索的敏感性,实验一被试为22名高中生,材料为三列含15个词语的清单,先逐个呈现词语系列位置信息,被试在学习前进行即刻学习判断,结果发现学习判断有显著首因效应,表明学习判断对系列位置信息这一外部线索比较敏感。实验二被试为20名高中生,先逐个呈现词语系列位置信息,被试在学习后进行即刻学习判断,结果发现学习判断同样有显著首因效应,表明学习判断对内部线索的敏感性并未强于外部线索。     

学习、笔画和线索注视时间对汉字知觉干扰效应的影响

采用经高斯模糊技术处理的汉字,以命名为任务,实验一考察了事先学习以及笔画数、实验二考察了笔画数和线索注视时间对干扰效应的影响.结果发现:1.无论是否学习,汉字识别均存在于扰效应;2.无论汉字笔画多少均存在干扰效应;3.模糊线索的注视时间足够长久之后不再影响干扰效应.这些结果似乎表明当激活超过一定水平时,和汉字激活水平有关的因素对知觉干扰效应不再起作用.     

部分线索效应的作用机制

部分线索效应指让学习者学习一系列材料,在随后的测试阶段,给学习者提供先前学习的部分材料作为提取线索,让学习者回忆剩余的材料,其回忆成绩反而比没有提取线索时回忆成绩差。该效应的经典理论模型主要有组织干扰假说和提取抑制假说。由于它们有许多分歧之处,最近提出的双机制解释试图将二者融合,显示了诸多优势,但同时也存在一些缺陷。对双机制解释的进一步探索应侧重于确定组织干扰的量、探讨部分线索相对持久抑制作用的过程、界定组织干扰假说和提取抑制假说的关系,此外对部分线索效应在实际学习生活中的检验也很重要。     

知觉负载和线索位置对视觉选择性注意的影响

采用线索范式,以汉语双字词为材料,探讨了不同工作记忆负荷条件下知觉负载、线索位置对视觉选择性注意的影响.结果表明:(1)线索位置影响被试对目标的加工,前线索条件下被试对目标的加工更为精细;(2)知觉负载对选择性注意的影响受到工作记忆的调节.高工作记忆负荷条件下,高知觉负载条件下的反应时显著短于低知觉负载条件;而在低工作记忆负荷条件下,不同知觉负载条件下的反应时差异不显著.     

真实场景视觉搜索中的背景线索效应特点与机制

背景线索效应揭示了个体在视觉搜索过程中对刺激之间具有的稳定空间关系(刺激间不变的相对空间位置)的学习能够提高搜索效率。本文基于经典背景线索效应在内隐习得空间布局的机制下结合真实场景视觉搜索的相关理论,对真实场景背景线索效应的实验范式、学习性质与内容进行归纳梳理,将真实场景视觉搜索中影响背景线索效应的视觉信息分为低水平物理特征及高水平语义信息两个维度进行论述。虽然当前研究涉及真实场景背景线索效应在不同场景维度信息的加工机制,但对于发挥作用的场景信息类别以及作用阶段还较少涉及,未来研究仍需进一步的探讨。     

Anticipatory Postural Adjustments for Altering Direction During Walking

The authors examined how individuals adapt their gait and regulate their body configuration before altering direction during walking. Eight young adults were asked to change direction during walking with different turning angles (0deg;, 45deg;, 90deg;), pivot foot (left, right), and walking speeds (normal and fast). The authors used video and force platform systems to determine participants' whole-body center of mass and the center of pressure during the step before they changed direction. The results showed that anticipatory postural adjustments occurred during the prior step and occurred earlier for the fast walking speed. Anticipatory postural adjustments were affected by all 3 variables (turn angle, pivot foot, and speed). Participants leaned backward and sideward on the prior step in anticipation of the turn. Those findings indicate that the motor system uses central control mechanisms to predict the required anticipatory adjustments and organizes the body configuration on the basis of the movement goal.     

Organization of Compensatory Postural Coordination Patterns

The authors investigated whether compensatory postural coordination patterns are organized according to the same dynamical principles as are nonequilibrium phase transitions. Eight participants were asked to maintain upright balance on a moving platform that was sinusoidally translated in the anterior-posterior direction and was systematically increased and decreased 0.19 Hz as a step function every 10 platform cycles through the frequency range 0.19–1.46 Hz. At low platform frequencies, all participants exhibited small joint angular motions with high variability, and the relative phase between the joint motions exhibited drifting patterns and large fluctuations. As platform frequency increased, the amplitude of joint motion increased systematically and joint-specific oscillatory patterns emerged. The findings provided no evidence for a Hopf bifurcation or hysteresis in the transitions of postural coordination modes, however, or, mote generally, a basis for distinguishing the relevance of linear versus nonlinear models of postural control.     

Altered Arm-Body Coordination with Triggered Pointing Responses as Influenced by Task Predictability

Abstract

Reaching movements generate reaction forces that affect postural stability, requiring sophisticated coordination between body and arm movement to maintain balance. In voluntary movement, this coordination involves feedforward shifts of posture, and such anticipatory postural muscle activity also accompanies the rapid modulation of an ongoing point to suddenly a shifting target (double-step). However, it is unknown if this early postural activity depends on target-shift predictability and whether arm and body motion are similar coordinated to voluntary movement. Body and arm motion coordination during double-step pointing movements from standing were done under differing conditions of target-shift predictability. In a proportion of trials, the pointing target was displaced, with the predictability of target-shift direction varied between two peripheral targets (target-shift direction known) and two central targets (target-shift direction uncertain). The target jump evoked an adjustment in the arm then body response, opposite to the pointing responses to the initial target. The triggered arm-then-body ordering was consistent across target-shift predictability, although known target-shift direction resulted in closer timing of arm and body onsets. The altered coordination in triggered corrections suggests that the body component in triggered reactions depend on response predictability, showing an altered control of arm and body motion.     

Effects of Varying Load Conditions on the Organization of Postural Adjustments during Voluntary Arm Flexion

One purpose of the experiments reported here was to further clarify the effect of varying loads on postural adjustments. Another was to reevaluate whether or not the timing of electromyographic (EMG) activity in the postural muscle is preprogrammed. To accomplish these goals, we compared the effect of the presence or absence of prior knowledge of a load on the timing of EMG activity in the postural muscle (biceps femoris [BF]) with that in the focal muscle (anterior deltoid [AD]). Although the sequence of EMG activation was similar under conditions with and without a load, the timing of postural EMG activities (BFi, ipsilateral BF; BFc, contralateral BF) in associated postural adjustments was dependent on the force of arm movement, and the latencies of postural EMG activities (BFi—BFc) were dependent on the speed of arm movement. This indicates that EMG changes in the upper (focal muscle) and lower limbs (postural muscle) were triggered by different motor programs. Moreover, similar EMG activities were observed in postural muscles when the subject had advance knowledge of the presence or the absence of a load. Thus, this suggests that BFi may be centrally preprogrammed (anticipatory regulation) and BFc may be feedback regulated. Furthermore, environmental information may be a critical source of influence on those postural responses.     

Violations of Fitts’ Law in a Ballistic Task

ABSTRACT

The authors explored changes in the postural preparation and movement times during jumps into targets of different sizes placed at different distances from the participant. Both movement and preparation times scaled with movement distance. Neither movement nor preparation time showed an effect of target size, although preparation time showed a tendency to increase for smaller targets. These observations show that the classical Fitts’ law can be violated in tasks that involve a ballistic component. The data corroborate a hypothesis that Fitts’ law originates at the level of movement planning.