视觉工作记忆的巩固加工：时程、模式及机制

在视觉工作记忆加工过程中, 对记忆项目的维持及操作需要将转瞬即逝的感觉输入转换为稳定的记忆表征, 这一加工过程被定义为视觉工作记忆巩固。鉴于巩固在视觉工作记忆中所起到的“门控”作用, 研究者们已经发展出多种研究范式对其可能涉及的运作机制进行探讨。然而, 在不同范式下所观察到的巩固时程存在较大差异, 其所遵循的巩固模式也尚不清晰。此外, 对于巩固所涉及的理论及神经机制亦存在不同的观点。通过对比不同范式的差异性及梳理各方的观点, 可以有效推动这些问题的解决。未来研究除了可以在多种范式下对巩固模式进行验证, 还可以探究注意在巩固中的作用, 以及项目熟悉性等因素会对巩固加工产生何种影响。     

Unique contribution of semantic representations to immediate memory: an individual-differences approach

Studies have reported dissociations between the contributions of semantic and phonological representations to immediate remembering, found through experimental manipulations as well as specific clinical cases. Also, some studies based on the analysis of individual differences reported that a semantic cued recall task has a variance unshared with the immediate memory tasks which tap the contribution of phonological representations. However, another study suggested that cued recall performance could reflect a wider ability to cluster information by category. Furthermore, no studies of individual differences have investigated the unique semantic contribution in the visual domain. Therefore, the present study used specific immediate recognition memory tasks that have been used to investigate the semantic contribution in the verbal and visual domains. The results demonstrate the unshared variance that reflects the semantic contribution in both the verbal and the visual domain, and some commonality in these variances across the domains.     

On the examination couch: the relationship between the egocentric perspective and the attentional focus

Determined by anatomical characteristics, the binocular visual field has an elliptical shape. Whereas the focus of attention – that area of the visual field in which objects can be consciously perceived – is significantly smaller, its shape is not necessarily dependent on the same factors. Indeed, it is yet unknown if the maximum extents of the attentional focus’ meridians are dimensionally stable or adapt to the egocentric perspective. In this study, we intended to measure the expansion up to which peripheral stimuli can still be perceived while participants were sitting and lying on the left and on the right body side. Results demonstrate that contrary to the visual field the maximum extents along the attentional focus’ meridians remain stable across different head positions with a greater horizontal than vertical alignment. This indicates that the expansion ratios of the meridians of the attentional focus are not dependent on the egocentric perspective. Rather, they appear stable in space and gravity-based. Findings are discussed in terms of our visual environment and current as well as alternative interpretations are weighed against each other.     

Face processing is enhanced in the left and upper visual hemi-fields

We tested whether two known hemi-field asymmetries would affect visual search with face stimuli. Holistic processing of spatial configurations is better in the left hemi-field, reflecting a right hemisphere specialization, and object recognition is better in the upper visual field, reflecting stronger projections into the ventral stream. Faces tap into holistic processing and object recognition at the same time, which predicts better performance in the left and upper hemi-field, respectively. In the first experiment, participants had to detect a face with a gaze direction different from the remaining faces. Participants were faster to respond when targets were presented in the left and upper hemi-field. The same pattern of results was observed when only the eye region was presented. In the second experiment, we turned the faces upside-down, which eliminated the typical spatial configuration of faces. The left hemi-field advantage disappeared, showing that it is related to holistic processing of faces, whereas the upper hemi-field advantage related to object recognition persisted. Finally, we made the search task easier by asking observers to search for a face with open among closed eyes or vice versa. The easy search task eliminated the need for complex object recognition and, accordingly, the advantage of the upper visual field disappeared. Similarly, the left hemi-field advantage was attenuated. In sum, our findings show that both horizontal and vertical asymmetries affect the search for faces and can be selectively suppressed by changing characteristics of the stimuli.     

Semantic and visual relatedness of distractors impairs episodic retrieval of pictures in a divided attention paradigm

We used a divided attention (DA) paradigm to infer the representational codes needed to support episodic retrieval of pictures, by measuring susceptibility to memory interference from different distracting tasks. Participants made recognition memory decisions to semantically categorized sets of pictures while simultaneously making size judgments to a set of visually-presented distractor pictures. Recognition accuracy was worse and response times were slower under DA conditions relative to full attention (FA), regardless of semantic relatedness of distractors to targets (Experiment 1). Similarly, we found no differential memory interference under DA relative to FA when distractor pictures were either visually (but not semantically), semantically (but not visually), or unrelated to the targets (Experiment 2). In Experiment 3, memory interference was significantly larger under DA at retrieval when distractors were both semantically and visually similar to the targets. Findings suggest episodic memory for pictures requires access to either visually- or semantically-based representations for optimal performance.     

视觉注意离散性的实验范式

注意离散性是注意间歇性地采集外界信息的特性。文章综述了视觉注意离散性的4种实验范式:(1)车轮错觉范式,刺激强度大、实验条件少、被试任务量小,较早地证实了视觉注意的离散性;(2)视觉探测范式,同时观察了被试的行为表现与电生理信号,确定了视觉注意离散性与神经振荡的关联;(3)线索靶子范式和视觉搜索范式,通过系统地变化SOA大幅提高了行为数据的时间分辨率,直观地探测到注意离散性调制的行为振荡。     

学习方法对陌生语言字形学习的影响

采用学习——测查的范式,以陌生视觉单词(韩字)为材料,考察了学习方法对陌生语言字形学习效果的影响。在学习阶段,材料分别以连续重复(集中学习)和间隔重复(分散学习)方式呈现6遍,在学习之后半小时、1天以及1个星期之后,分别进行再认记忆测查。结果发现,虽然随着测查间隔时间的增长,两种学习条件的成绩都显著降低,但是在三次测查中,分散学习的成绩都明显好于集中学习。这一结果说明在排除语音、语义等其他言语元素的干扰之后,以分散学习的方式学习新字形的效果好于集中学习。     

Word recognition in Alzheimer's disease: Effects of semantic degeneration

Impairments of word recognition in Alzheimer's disease (AD) have been less widely investigated than impairments affecting word retrieval and production. In particular, we know little about what makes individual words easier or harder for patients with AD to recognize. We used a lexical selection task in which participants were shown sets of four items, each set consisting of one word and three non‐words. The task was simply to point to the word on each trial. Forty patients with mild‐to‐moderate AD were significantly impaired on this task relative to matched controls who made very few errors. The number of patients with AD able to recognize each word correctly was predicted by the frequency, age of acquisition, and imageability of the words, but not by their length or number of orthographic neighbours. Patient Mini‐Mental State Examination and phonological fluency scores also predicted the number of words recognized. We propose that progressive degradation of central semantic representations in AD differentially affects the ability to recognize low‐imageability, low‐frequency, late‐acquired words, with the same factors affecting word recognition as affecting word retrieval.     

Learning words and learning sounds: Advances in language development

Phonological development is sometimes seen as a process of learning sounds, or forming phonological categories, and then combining sounds to build words, with the evidence taken largely from studies demonstrating ‘perceptual narrowing’ in infant speech perception over the first year of life. In contrast, studies of early word production have long provided evidence that holistic word learning may precede the formation of phonological categories. In that account, children begin by matching their existing vocal patterns to adult words, with knowledge of the phonological system emerging from the network of related word forms. Here I review evidence from production and then consider how the implicit and explicit learning mechanisms assumed by the complementary memory systems model might be understood as reconciling the two approaches.     

Attentional capture in driving displays

Drivers face frequent distraction on the roadways, but little is known about situations placing them at risk of misallocating visual attention. To investigate this issue, we asked participants to search for a red target embedded within simulated driving scenes (photographs taken from inside a car) in three experiments. Distraction was induced by presenting, via a GPS unit, red or green distractors positioned in an irrelevant location at which the target never appeared. If the salient distractor captures attention, visual search should be slower on distractor‐present trials than distractor‐absent trials. In Experiment 1, salient distractors yielded no such capture effect. In Experiment 2, we decreased the frequency of the salient distractor from 50% of trials to only 10% or 20% of trials. Capture effects were almost five times larger for the 10% occurrence group than for the 20% occurrence group. In Experiment 3, the amount of available central resources was manipulated by asking participants to either simultaneously monitor or ignore a stream of spoken digits. Capture effects were much larger for the dual‐task group than for the single‐task group. In summary, these findings identify risk factors for attentional capture in real‐world driving scenes: distractor rarity and diversion of attention.