双眼竞争的混合模型

双眼竞争是指当双眼所呈现的图像不一致而无法形成单一、稳定的知觉进而造成知觉动态交替变化的现象,双眼竞争的特殊性(刺激不变,而知觉却发生交替变化)使其成为神经科学、心理学、生理学和临床医学中的研究热点.Frank Tong等人 综合各方面的实验结果将双跟竞争的早期加工和晚期加工有机地结合起来,提出了双眼竞争的多层次-混合加工理论模型,这一模型对于研究视觉意识的神经机制、知觉组织及选择性注意具有重要的理论指导意义.作者文末就双眼竞争中仍需进一步研究和证实的主要问题进行了总结.     

整体/局部加工中的半球功能不对称效应

20世纪末的研究证据显示,对Navon等级刺激的整体/局部加工中半球功能不对称效应发生在早期还是晚期阶段,研究者存在着争论。近期的电生理和功能成像研究资料表明,整体/局部加工的半球不对称效应可能是一个受到多种因素调节的复杂动态系统;早期信息表征的半球功能不对称效应可能主要受知觉因素的影响,而注意控制和反应冲突可能主要调节晚期知觉加工的半球功能不对称     

特殊的视错觉：运动诱导视盲

突显的静止目标被一定空间范围内运动背景所覆盖时, 人类会感受到静止目标消失再重现的发生, 这种视错觉现象叫做运动诱导视盲(motion-induced blindness, MIB)。该现象成因的理论解释主要有：注意竞争理论、知觉完型加工理论以及神经生理机制相关理论。作为特殊的视错觉现象, 该现象与其他盲视现象不同,主要是由客体识别过程中的知觉变化引起; 另一方面, 运动诱导视盲中“反知觉”现象的特殊性也是研究者关注的问题之一。神经生理机制层面的研究关注早期、晚期皮层在该现象发生时的变化, 采用眼动、脑电等技术对错觉现象发生时程进行测量与评估。文章在总结已有相关研究的基础上进一步指出今后可深入探索的研究方向有：MIB发生的深层机制、作为研究意识神经相关、无意识知觉加工等课题的工具、MIB中的意义性加工与认知冲突等。     

语言范畴影响面部表情知觉的电生理学证据

本研究探讨了语言范畴影响面部表情知觉的时程及大脑偏侧化特点。采用从快乐到恐惧渐变的4张人类面孔表情图片为实验材料，以分视野呈现刺激的oddball范式设计脑电实验，并以分心任务使被试不注意实验表情图片之间的差异。实验结果显示，表情知觉诱发的ERP成分N1和N2上均出现了偏右视野-左脑表情范畴知觉，即在右视野呈现的条件下，范畴间偏差刺激比范畴内偏差刺激诱发了更大的vMMN效应，而在左视野呈现的条件下，两类偏差刺激诱发的vMMN效应无显著差异。这一结果表明表情范畴知觉发生在表情知觉的早期感觉水平加工及后知觉加工阶段，且具有偏右视野-左脑特性，提示语言范畴会同时影响早期、注意前表情知觉及后知觉加工，支持了沃尔夫假说。     

面孔审美加工的神经机制及个体差异

外显和内隐的面孔审美加工的脑成像研究表明,美的面孔比不美的面孔导致眶额皮层、伏隔核、杏仁核等奖赏脑区更大的激活。脑电研究则发现了与面孔审美加工有关的早期负波和晚期正成分。面孔审美加工有关的脑区活动也受到性别、生理周期等个体因素的调节。未来的研究需要比较美的面孔与其它奖赏刺激加工的神经机制,探讨面孔审美加工的不同阶段及时间进程,在面孔知觉的框架下形成合理的面孔审美加工的神经模型。     

视觉短时记忆与视知觉的信息整合

与知觉整合和跨眼跳的信息整合一样,视觉短时记忆与视知觉的信息整合也是人们加工并保持整体性场景知觉的重要前提条件。近年来研究者们使用空白单元格定位任务进行了一些研究,试图寻求视觉短时记忆与视知觉信息整合的实验证据并探讨其整合机制。该文对已有的相关实验范式、实验证据和整合机制进行了介绍并加以分析,并指出未来研究可以在行为数据的基础上结合眼动和脑成像的数据寻求汇聚性证据     

知觉启动效应及其脑机制的研究进展

该文从三个方面对知觉启动效应研究进行了回顾：(1)知觉启动的一般特征：(2)刺激的物理特征与知觉启动之间的关系;(3)知觉启动的神经解剖基础及神经机制。该文指出．知觉启动主要加工刺激表面的物理特征;刺激的大小、位置、颜色、模式等特征尽管对知觉启动有影响．但刺激的形状和结构等特征对于知觉启动更重要;知觉启动主要受枕部皮层的调节。最后,讨论了几个有关知觉启动机制的理论假说。     

注意促进效应:注意与记忆关系的新见解

注意资源通常被认为是有限的,因此编码时的双任务操作会分散注意资源,从而削弱随后的记忆成绩。但Swallow和Jiang(2010)发现,目标探测性质的二级任务不仅不会削弱记忆成绩,甚至可能会提高记忆成绩,产生注意促进效应(Attentional Boost Effect,ABE),并于2013年提出ABE的双任务交互作用模型。该模型认为,ABE的产生是源于目标探测反应触发了暂时性的时间选择性注意机制,促进了对同时呈现的背景信息在编码早期的知觉加工。但随后的一些实验结果却与该模型存在着矛盾,暗示着ABE可能并不只源于背景信息的知觉加工增强;ABE与分心拒绝下的抑制并非完全无关;ABE并不只产生于编码的早期阶段等。因此未来研究仍需继续探索或修正ABE的产生机制及理论模型。     

自然物体分类的ERP研究

对事物进行分类的能力是人类的一种基本认知功能。该文主要就近年来自然物体分类的事件相关电位（ERP）研究情况进行综述。首先介绍与自然物体分类有关的ERP早晚期成分;接着讨论了快速视觉分类的加工机制,认为前馈机制在这种复杂分类任务的视觉加工过程中起重要作用;最后详细介绍了两个分离的视觉加工机制,认为自然物体的视觉分类在不同时程涉及不同机制：即首先是任务无关的早期知觉加工过程,其次是任务相关的、类别无关的加工机制,与被试的决策有关。也讨论了这两个分离的加工过程涉及的神经基础。     

人名相关自我加工的时间过程——事件相关电位研究提供的电生理证据

本研究采用事件相关电位技术（ERP）探讨了自我名字加工的神经机制。实验中向被试随机呈现大圆、小圆及名字,被试的任务是辨别大圆和小圆,名字是任务无关刺激。实验结果表明,被试自己的名字引发的P2及P3波幅都显著高于名人的名字及陌生人的名字。 与以往研究结果不同,本研究发现了P2波幅上的“自我名字效应”,即,人名相关的自我加工不仅表现在晚期成分P3上,同时还表现在早期成分P2上。所以,人名相关的自我加工过程分为早期和晚期两个加工阶段,前一个阶段可能是自动化加工,不需要意识参与,后一个阶段是意识加工。     

"Binaural rivalry": dichotic listening as a tool for the investigation of the neural correlate of consciousness

Since about two decades neuroscientists have systematically faced the problem of consciousness: the aim is to discover the neural activity specifically related to conscious perceptions, i.e. the biological properties of what philosophers call qualia. In this view, a neural correlate of consciousness (NCC) is a precise pattern of brain activity that specifically accompanies a particular conscious experience. Almost all studies aimed at investigating the NCC have been carried out in the visual system. One of the most promising paradigms is based on sensory stimuli which elicit bistable percepts, as they allow to decouple subjective perception from the characteristics of the physical stimulation. Such kind of perception can be produced in the visual modality by using particular images (e.g. Rubin's vase/face figure) or by presenting two dissimilar stimuli separately to the two eyes (binocular rivalry). The stimuli compete for perceptual dominance and each image is visible in turn for a few seconds, while the other is suppressed. The use of this methodology has led to important findings concerning visual consciousness, which are briefly discussed. For the investigation of auditory consciousness, a similar stimulation paradigm can be achieved by using dichotic listening, consisting in two different stimuli presented each to one ear, which compete for perception (binaural rivalry). The principal aim of the present mini-review is to discuss the few contributes facing the issue of auditory consciousness and to advance the use of dichotic listening and binaural rivalry as valid tools for its investigation.     

Emotional pictures predominate in binocular rivalry

This study used binocular rivalry to examine whether emotionally relevant pictures are processed preferentially in the visual system. Binocular rivalry occurs when two incompatible pictures are presented to both eyes. If the pictures cannot be merged to a single unambiguous percept, binocular rivalry results in an alternation of the two percepts. However, it has been controversial whether emotional picture content can influence a picture's relative predominance. Twenty pairs of emotional and neutral pictures from the International Affective Picture System (IAPS) were presented to 45 healthy participants. As hypothesised, emotional pictures significantly predominated over neutral pictures, both with respect to the first percept and the total viewing time across each trial. We conclude that the relative predominance of emotional pictures in binocular rivalry provides further support for the preferential processing of emotional stimuli in the visual system.     

A common oscillator for perceptual rivalries?

Perceptual rivalry is an oscillation of conscious experience that takes place despite univarying. if ambiguous, sensory input. Much current interest is focused on the controversy over the neural site of binocular rivalry, a variety of perceptual rivalry for which a number of different cortical regions have been implicated. Debate continues over the relative role of higher levels of processing compared with primary visual cortex and the suggestion that different forms of rivalry involve different cortical areas. Here we show that the temporal pattern of disappearance and reappearance in motion-induced blindness (MIB) (Bonneh et al, 2001 Nature 411 798-801) is highly correlated with the pattern of oscillation reported during binocular rivalry in the same individual. This correlation holds over a wide range of inter-individual variation. Temporal similarity in the two phenomena was strikingly confirmed by the effects of the hallucinogen LSD, which produced the same, extraordinary, pattern of increased rhythmicity in both kinds of perceptual oscillation. Furthermore. MIB demonstrates the two properties previously considered characteristic of binocular rivalry. Namely the distribution of dominance periods can be approximated by a gamma distribution and, in line with Levelt's second proposition of binocular rivalry, predominance of one perceptual phase can be increased through a reduction in the predominance time of the opposing phase. We conclude that (i) MIB is a form of perceptual rivalry, and (ii) there may be a common oscillator responsible for timing aspects of all forms of perceptual rivalry.     

Psychophysical magic: rendering the visible 'invisible'

What are the neural correlates of conscious visual awareness? Tackling this question requires contrasting neural correlates of stimulus processing culminating in visual awareness with neural correlates of stimulus processing unaccompanied by awareness. To produce these two neural states, one must be able to erase an otherwise visible stimulus from awareness. This article describes and assesses visual phenomena involving dissociation of physical stimulation and conscious awareness: degraded stimulation, visual masking, visual crowding, bistable figures, binocular rivalry, motion-induced blindness, inattentional blindness, change blindness and attentional blink. No single approach stands above the others, but those producing changing visual awareness despite invariant physical stimulation are clearly preferable. Such phenomena can help lead us ultimately to a comprehensive account of the neural correlates of conscious awareness.     

Implicit semantic perception in object substitution masking

Decades of research on visual perception has uncovered many phenomena, such as binocular rivalry, backward masking, and the attentional blink, that reflect ‘failures of consciousness’. Although stimuli do not reach awareness in these paradigms, there is evidence that they nevertheless undergo semantic processing. Object substitution masking (OSM), however, appears to be the exception to this rule. In OSM, a temporally-trailing four-dot mask interferes with target perception, even though it has different contours from and does not spatially overlap with the target. Previous research suggests that OSM has an early locus, blocking the extraction of semantic information. Here, we refute this claim, showing implicit semantic perception in OSM using a target-mask priming paradigm. We conclude that semantic information suppressed via OSM can nevertheless guide behavior.     

Neural bases of binocular rivalry

During binocular rivalry, conflicting monocular images compete for access to consciousness in a stochastic, dynamical fashion. Recent human neuroimaging and psychophysical studies suggest that rivalry entails competitive interactions at multiple neural sites, including sites that retain eye-selective information. Rivalry greatly suppresses activity in the ventral pathway and attenuates visual adaptation to form and motion; nonetheless, some information about the suppressed stimulus reaches higher brain areas. Although rivalry depends on low-level inhibitory interactions, high-level excitatory influences promoting perceptual grouping and selective attention can extend the local dominance of a stimulus over space and time. Inhibitory and excitatory circuits considered within a hybrid model might account for the paradoxical properties of binocular rivalry and provide insights into the neural bases of visual awareness itself.     

The role of voluntary and involuntary attention in selecting perceptual dominance during binocular rivalry

When incompatible images are presented to corresponding regions of each eye, perception alternates between the two monocular views (binocular rivalry). In this study, we have investigated how involuntary (exogenous) and voluntary (endogenous) attention can influence the perceptual dominance of one rival image or the other during contour rivalry. Subjects viewed two orthogonal grating stimuli that were presented to both eyes. Involuntary attention was directed to one of the grating stimuli with a brief change in orientation. After a short period, the cued grating was removed from the image in one eye and the uncued grating was removed from the image in the other eye, generating binocular rivalry. Subjects usually reported dominance of the cued grating during the rivalry period. We found that the influence of the cue declined with the interval between its onset and the onset of binocular rivalry in a manner consistent with the effect of involuntary attention. Finally, we demonstrated that voluntary attention to a grating stimulus could also influence the ongoing changes in perceptual dominance that accompany longer periods of binocular rivalry Voluntary attention did not increase the mean dominance period of the attended grating, but rather decreased the mean dominance period of the non-attended grating. This pattern is analogous to increasing the perceived contrast of the attended grating. These results suggest that the competition during binocular rivalry might be an example of a more general attentional mechanism within the visual system.     

Aftereffects in binocular rivalry

Five experiments are reported in which the aftereffect paradigm was applied to binocular rivalry. In the first three experiments rivalry was between a vertical grating presented to the left eye and a horizontal grating presented to the right eye. In the fourth experiment the rivalry stimuli consisted of a rotating sectored disc presented to the left eye and a static concentric circular pattern presented to the right. In experiment 5 rivalry was between static radiating and circular patterns. The predominance durations were systematically influenced by direct (same eye) and indirect (interocular) adaptation in a manner similar to that seen for spatial aftereffects. Binocular adaptation produced an aftereffect that was significantly smaller than the direct aftereffect, but not significantly different from the indirect one. A model is developed to account for the results; it involves two levels of binocular interaction in addition to monocular channels. It is suggested that the site of spatial aftereffects is the same as that for binocular rivalry, rather than sequentially prior.