超文本阅读绩效研究述评——认知的视角

网络不同于传统媒介的最大特点是以灵活的超文本形式呈现信息,超文本将关联的信息以网络状形式加以组织,读者可以通过链接从一个节点跳转到其他任何一个节点。本文回顾了超文本阅读的研究历程,指出目前这一领域研究存在的困境并试图寻找原因,在此基础上提出了今后研究的建议。     

神经肌肉下意识前馈与反馈控制的知觉线索效应

为研究视觉和时间知觉线索对突发外部姿势干扰下中枢神经系统对动作肌肉和姿势肌肉预期姿势调节(APAs)和补偿姿势调节(CPAs)的影响, 本研究被试分别在视觉和时间线索引导下完成经典落球试验, 同步采集右侧动作肌肉肱二头肌和姿势肌肉腰部竖脊肌和腰部多裂肌的sEMG信号, 计算被检肌肉APAs发生率、预激活时间和CPAs反应强度。结果发现, 视觉线索可以引发动作肌肉和姿势肌肉APAs发生率明显增加, 预激活时间明显提前, 以及动作肌肉CPAs反应强度明显减小; 而时间线索主要引发动作肌肉预激活提前, 对姿势肌肉APAs和CPAs无明显影响。该结果表明, 视觉和时间引导线索对突发外部姿势干扰条件下人体姿势肌肉和动作肌肉的中枢运动控制具有不同的作用。视觉引导线索能够明显增加姿势肌肉和动作肌肉预激活发生率和提早预激活时间, 表现出明显的“视觉线索预激活优势现象”; 而时间引导线索主要引发动作肌肉预激活提前, 对姿势肌肉APAs和CPAs无明显影响。     

背景图相关度与知觉流畅性对意义材料学习的影响

可取难度理论和不流畅理论认为不流畅加工可促进学习,认知负荷理论则认为知觉不流畅所激发的额外认知负荷可能阻碍学习。研究采用2（知觉流畅性：流畅,不流畅）×3（背景图相关度：相关背景图、无关背景图和空白背景）被试间实验设计,考察学习意义材料时认知负荷（通过插入的背景图控制）与知觉流畅性的相互作用。结果发现：（1）知觉流畅性的主效应显著,知觉流畅时的学习成绩显著高于知觉不流畅时的成绩;背景图相关度的主效应显著,相关背景图条件下的成绩显著高于空白背景和无关背景图。（2）知觉流畅性与背景图相关度的交互作用显著,在知觉流畅条件下,呈现相关背景图的得分显著高于空白背景和无关背景图,后二者无显著差异;知觉不流畅条件下,三者间无显著差异。研究结果表明,在知觉流畅的条件下插入相关背景图有利于意义材料的学习;该结果支持认知负荷理论。     

诱发的积极情绪会促进多媒体学习吗?

近来, 教育心理学领域开始关注情绪因素对多媒体学习的影响, 其中诱发情绪逐渐成为研究者关注的指导设计形式。已有研究主要通过外部情绪诱发和内部情绪设计来考察诱发的积极情绪在学习过程中的作用, 并发现外部情绪诱发和内部情绪设计能够成功诱发积极情绪, 但由于情绪诱发方式的多样性和多媒体学习过程的复杂性, 诱发的积极情绪对学习效果的促进作用比较微弱。综述发现, 7项涉及外部情绪诱发的实验在学习结果上产生的效应量中值分别为d_保持 = -0.25, d_理解 = 0.04, d_迁移 = 0.30; 14项涉及内部情绪设计的实验在学习结果上产生的效应量中值分别为d_保持 = 0.27, d_理解 = 0.36, d_迁移 = 0.29。诱发的情绪对学习过程的主观体验影响很小。多媒体学习认知情感理论认为诱发的积极情绪会通过动机的中介作用进而促进学习; 相反, 认知负荷理论认为诱发的积极情绪会增加学习者的外在认知负荷从而阻碍学习。未来研究仍需关注情绪的操纵方法、效果评定以及潜在调节变量的作用等。     

The effects of task-irrelevant threatening stimuli on orienting- and executive attentional processes under cognitive load

Human visual attention is biased to rapidly detect threats in the environment so that our nervous system can initiate quick reactions. The processes underlying threat detection (and how they operate under cognitive load), however, are still poorly understood. Thus, we sought to test the impact of task-irrelevant threatening stimuli on the salience network and executive control of attention during low and high cognitive load. Participants were exposed to neutral or threatening pictures (with moderate and high arousal levels) as task-irrelevant distractors in near (parafoveal) and far (peripheral) positions while searching for numbers in ascending order in a matrix array. We measured reaction times and recorded eye-movements. Our results showed that task-irrelevant distractors primarily influenced behavioural measures during high cognitive load. The distracting effect of threatening images with moderate arousal level slowed reaction times for finding the first number. However, this slowing was offset by high arousal threatening stimuli, leading to overall shorter search times. Eye-tracking measures showed that participants fixated threatening pictures more later and for shorter durations compared to neutral images. Together, our results indicate a complex relationship between threats and attention that results not in a unitary bias but in a sequence of effects that unfold over time.     

The role of perceptual load in inattentional blindness

Perceptual load theory offers a resolution to the long-standing early vs. late selection debate over whether task-irrelevant stimuli are perceived, suggesting that irrelevant perception depends upon the perceptual load of task-relevant processing. However, previous evidence for this theory has relied on RTs and neuroimaging. Here we tested the effects of load on conscious perception using the "inattentional blindness" paradigm. As predicted by load theory, awareness of a task-irrelevant stimulus was significantly reduced by higher perceptual load (with increased numbers of search items, or a harder discrimination vs. detection task). These results demonstrate that conscious perception of task-irrelevant stimuli critically depends upon the level of task-relevant perceptual load rather than intentions or expectations, thus enhancing the resolution to the early vs. late selection debate offered by the perceptual load theory.     

Failure to warn: How student race affects warnings of potential academic difficulty

In two studies, we document “failure to warn”—a reduced likelihood of warning Black students against potential academic difficulty compared to White students. In both studies, participants placed in the role of academic advisors saw a highly challenging academic course plan, attributed to either a Black or a White student, and gave Black students less warning about the potential negative consequences of taking on the proposed plan. Study 1 (N = 172) demonstrates this effect using undergraduate peer academic advisors, and Study 2 (N = 58) provides evidence that this effect is moderated by Internal Motivation to Respond Without Prejudice (Plant & Devine, 1998), suggesting that this effect is driven by the fear that discouraging an ambitious Black student might reflect prejudice. This well-intentioned concern can have the ironic consequence of leading the recipients of this advice into academic difficulties.     

Neural correlates of variable working memory load across adult age and skill: dissociative patterns within the fronto-parietal network

We examined neural changes related to variations in working memory load by using an n -back task with three levels and functional magnetic resonance imaging. Younger adults were divided into high- and low-performing groups (Young-High; Young-Low) and compared with older adults. Relative to Young-High, capacity-constraints in working memory were apparent between load 1–2 for the elderly and between load 2–3 for Young-Low. Capacity-constraints in neural activity followed this pattern by showing a monotonically increasing response in parietal cortex and thalamus for Young-High, whereas activity leveled off at 1-back for the elderly and at 2-back for Young-Low. The response in dorsal frontal cortex followed a similar pattern with the addition that the magnitude of activation differed within capacity limitations (Old > Young at 1-back; Young-Low > Young-High at 2-back). These findings indicate that an important determinant of WM capacity is the ability to keep the frontal cortex adequately engaged in relation to current task demands.