Attention control in the primate brain

Attention is fundamental to all cognition. In the primate brain, it is implemented by a large-scale network that consists of areas spanning across all major lobes, also including subcortical regions. Classical attention accounts assume that control over the selection process in this network is exerted by ‘top-down’ mechanisms in the fronto-parietal cortex that influence sensory representations via feedback signals. More recent studies have expanded this view of attentional control. In this review, we will start from a traditional top-down account of attention control, and then discuss more recent findings on feature-based attention, thalamic influences, temporal network dynamics, and behavioral dynamics that collectively lead to substantial modifications. We outline how the different emerging accounts can be reconciled and integrated into a unified theory.     

Feature-based attention: it is all bottom-up priming

Feature-based attention (FBA) enhances the representation of image characteristics throughout the visual field, a mechanism that is particularly useful when searching for a specific stimulus feature. Even though most theories of visual search implicitly or explicitly assume that FBA is under top-down control, we argue that the role of top-down processing in FBA may be limited. Our review of the literature indicates that all behavioural and neuro-imaging studies investigating FBA suffer from the shortcoming that they cannot rule out an effect of priming. The mere attending to a feature enhances the mandatory processing of that feature across the visual field, an effect that is likely to occur in an automatic, bottom-up way. Studies that have investigated the feasibility of FBA by means of cueing paradigms suggest that the role of top-down processing in FBA is limited (e.g. prepare for red). Instead, the actual processing of the stimulus is needed to cause the mandatory tuning of responses throughout the visual field. We conclude that it is likely that all FBA effects reported previously are the result of bottom-up priming.     

不同注意任务类型及难度对猕猴微眼动的影响

微眼动是视觉注视过程中幅度最大、速度最快的眼动,可以消除由于神经系统适应性而产生的视觉衰退现象,在视觉信息处理过程中发挥着重要作用.基于微眼动与视觉感知功能的相关性,设计实验研究猕猴完成显性、隐性注意任务以及不同难度显性注意任务时,视觉注视情况下微眼动的差异.通过对不同难度显性注意任务下微眼动的参数进行比较,发现随着任务难度的增加,微眼动的幅度、速率和频率都被抑制.另一方面,对比不同类型的视觉感知任务(显性注意和隐性注意),发现在相似的实验范式下,隐性注意对微眼动的频率有明显的抑制作用,但幅度和频率没有得到一致的结果,这表明视觉注意任务类型的不同或将导致猕猴完成任务的策略不同.这些工作将为今后进一步研究微眼动产生的神经机制以及视觉注意过程中眼动的作用机制奠定良好的基础.     

Intergroup threat gates social attention in humans

Humans shift their attention to follow another person''s gaze direction, a phenomenon called gaze cueing. This study examined whether a particular social factor, intergroup threat, modulates gaze cueing. As expected, stronger responses of a particular in-group to a threatening out-group were observed when the in-group, conditioned to perceive threat from one of two out-groups, was presented with facial stimuli from the threatening and non-threatening out-groups. These results suggest that intergroup threat plays an important role in shaping social attention. Furthermore, larger gaze-cueing effects were found for threatening out-group faces than for in-group faces only at the 200 ms but not the 800 ms stimulus onset asynchrony (SOA); the specificity of the gaze-cueing effects at the short SOA suggests that threat cues modulate the involuntary component of gaze cueing.     

Attention driven phantom vision: measuring the sensory strength of attentional templates and their relation to visual mental imagery and aphantasia

When we search for an object in an array or anticipate attending to a future object, we create an ‘attentional template'' of the object. The definitions of attentional templates and visual imagery share many similarities as well as many of the same neural characteristics. However, the phenomenology of these attentional templates and their neural similarities to visual imagery and perception are rarely, if ever discussed. Here, we investigate the relationship between these two forms of non-retinal phantom vision through the use of the binocular rivalry technique, which allows us to measure the sensory strength of attentional templates in the absence of concurrent perceptual stimuli. We find that attentional templates correlate with both feature-based attention and visual imagery. Attentional templates, like imagery, were significantly disrupted by the presence of irrelevant visual stimuli, while feature-based attention was not. We also found that a special population who lack the ability to visualize (aphantasia), showed evidence of feature-based attention when measured using the binocular rivalry paradigm, but not attentional templates. Taken together, these data suggest functional similarities between attentional templates and visual imagery, advancing the theory of visual imagery as a general simulation tool used across cognition.This article is part of the theme issue ‘Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation’.     

A Feedback Model of Attention and Context Dependence in Visual Cortical Networks

We have modeled biologically realistic neural networks that may be involved in contextual modulation of stimulus responses, as reported in the neurophysiological experiments of Motter (1994a, 1994b) (Journal of Neuroscience, 14:2179–2189 and 2190–2199). The networks of our model are structured hierarchically with feedforward, feedback, and lateral connections, totaling several thousand cells and about 300,000 synapses. The contextual modulation, arising from attention cues, is explicitly modeled as a feedback signal coming from the highest-order cortical network. The feedback signal arises from mutually inhibitory neurons with different stimulus preferences. Although our model is probably the simplest one consistent with available anatomical and physiological evidence and ignores the complexities that may exist in high-level cortical networks such as the prefrontal cortex, it reproduces the experimental results quite well and offers some guidance for future experiments. We also report the unexpected observation of 40 Hz oscillations in the model.     

Social orienting in gaze leading: a mechanism for shared attention

Here, we report a novel social orienting response that occurs after viewing averted gaze. We show, in three experiments, that when a person looks from one location to an object, attention then shifts towards the face of an individual who has subsequently followed the person''s gaze to that same object. That is, contrary to ‘gaze following’, attention instead orients in the opposite direction to observed gaze and towards the gazing face. The magnitude of attentional orienting towards a face that ‘follows’ the participant''s gaze is also associated with self-reported autism-like traits. We propose that this gaze leading phenomenon implies the existence of a mechanism in the human social cognitive system for detecting when one''s gaze has been followed, in order to establish ‘shared attention’ and maintain the ongoing interaction.     

线索有效性对社会性注意和外源性注意的影响

目的 眼睛注视、头朝向和生物运动方向等社会性线索,对人类的生存和社会交互极为重要.由于社会性线索和外周线索都具有反射性注意定向这一特点,社会性注意往往也被认为属于外源性注意.但是,外源性注意并不能完全解释所有的社会性注意现象.因此,两者是否具有相同的加工机制,尚存在争论.方法 本研究使用空间线索范式,系统考察了线索有效...     

Grapheme-colour synaesthesia improves detection of embedded shapes,but without pre-attentive ‘pop-out’ of synaesthetic colour

For people with synaesthesia letters and numbers may evoke experiences of colour. It has been previously demonstrated that these synaesthetes may be better at detecting a triangle made of 2s among a background of 5s if they perceive 5 and 2 as having different synaesthetic colours. However, other studies using this task (or tasks based on the same principle) have failed to replicate the effect or have suggested alternative explanations of the effect. In this study, we repeat the original study on a larger group of synaesthetes (n = 36) and include, for the first time, an assessment of their self-reported colour experiences. We show that synaesthetes do have a general advantage over controls on this task. However, many synaesthetes report no colour experiences at all during the task. Synaesthetes who do report colour typically experience around one third of the graphemes in the display as coloured. This is more consistent with theories of synaesthesia in which spatial attention needs to be deployed to graphemes for conscious colour experiences to emerge than the interpretation based on ‘pop-out’.     

选择性注意的统一模型

根据ＰＥＴ、ＥＲＰ和心理学实验的事实,提出选择性注意的统一模型。在统一模型,把探照灯模型和偏置竞争模型和特点结合起来,既包括竞争机制,又包括增强机制。     

Synchronization of spontaneous eyeblinks while viewing video stories

Blinks are generally suppressed during a task that requires visual attention and tend to occur immediately before or after the task when the timing of its onset and offset are explicitly given. During the viewing of video stories, blinks are expected to occur at explicit breaks such as scene changes. However, given that the scene length is unpredictable, there should also be appropriate timing for blinking within a scene to prevent temporal loss of critical visual information. Here, we show that spontaneous blinks were highly synchronized between and within subjects when they viewed the same short video stories, but were not explicitly tied to the scene breaks. Synchronized blinks occurred during scenes that required less attention such as at the conclusion of an action, during the absence of the main character, during a long shot and during repeated presentations of a similar scene. In contrast, blink synchronization was not observed when subjects viewed a background video or when they listened to a story read aloud. The results suggest that humans share a mechanism for controlling the timing of blinks that searches for an implicit timing that is appropriate to minimize the chance of losing critical information while viewing a stream of visual events.     

Independent effects of endogenous and exogenous attention in touch

Abstract

Endogenous and exogenous attention in touch have typically been investigated separately. Here we use a double-cueing paradigm manipulating both types of orienting in each trial. Bilateral endogenous cues induced long-lasting facilitation of endogenous attention up to 2?s. However, the exogenous cue only elicited an effect at short intervals. Our results favour a supramodal account of attention and this study provides new insight into how endogenous and exogenous attention operates in the tactile modality.     

7～12月婴儿注意发展的特点(英文)

目的:探讨7～12月婴儿的注意发展的特点及影响因素。方法:将5种该年龄组感兴趣的玩具依次呈现给婴儿,使其不受干扰自由玩耍并全程摄像,采用录像记录回放法,对75名婴儿的注意力特点进行测试分析。结果:75名婴儿对五个玩具平均每分钟注意的总时间为15.1±5.9秒、专注注意的平均时间7.1±4.4秒、随意注意的平均时间为8.0±3.5秒。方差分析结果显示:婴儿对5种玩具注意时间存在显著性差异,总注意、专注注意、随意注意的F值分别为26.2、11.4、27.7,P值均小于0.001。采用LSD-t检验进行均数两两比较,方木与、书与其他4种玩具注意时间存在显著性差异。结论:7～12月婴儿的注意力与玩具设置的新异性及复杂程度有关。     

Attending to the possibilities of action

Actions taking place in the environment are critical for our survival. We review evidence on attention to action, drawing on sets of converging evidence from neuropsychological patients through to studies of the time course and neural locus of action-based cueing of attention in normal observers. We show that the presence of action relations between stimuli helps reduce visual extinction in patients with limited attention to the contralesional side of space, while the first saccades made by normal observers and early perceptual and attentional responses measured using electroencephalography/event-related potentials are modulated by preparation of action and by seeing objects being grasped correctly or incorrectly for action. With both normal observers and patients, there is evidence for two components to these effects based on both visual perceptual and motor-based responses. While the perceptual responses reflect factors such as the visual familiarity of the action-related information, the motor response component is determined by factors such as the alignment of the objects with the observer''s effectors and not by the visual familiarity of the stimuli. In addition to this, we suggest that action relations between stimuli can be coded pre-attentively, in the absence of attention to the stimulus, and action relations cue perceptual and motor responses rapidly and automatically. At present, formal theories of visual attention are not set up to account for these action-related effects; we suggest ways that theories could be expected to enable action effects to be incorporated.     

时间选择性注意的认知神经机制

时间选择性注意是注意研究中开展较晚的一个领域,它是指通过有效的提示,将注意资源导向与即将到来的事件相关的时间点或时间窗的过程．回顾了时间选择性注意的行为及其认知神经机制的研究,并在与空间选择性注意比较的基础上,对热点问题和未来的研究趋势进行了分析．     

Social status gates social attention in humans

Humans tend to shift attention in response to the averted gaze of a face they are fixating, a phenomenon known as gaze cuing. In the present paper, we aimed to address whether the social status of the cuing face modulates this phenomenon. Participants were asked to look at the faces of 16 individuals and read fictive curriculum vitae associated with each of them that could describe the person as having a high or low social status. The association between each specific face and either high or low social status was counterbalanced between participants. The same faces were then used as stimuli in a gaze-cuing task. The results showed a greater gaze-cuing effect for high-status faces than for low-status faces, independently of the specific identity of the face. These findings confirm previous evidence regarding the important role of social factors in shaping social attention and show that a modulation of gaze cuing can be observed even when knowledge about social status is acquired through episodic learning.     

A blinking focal pattern of re-entrant activity in the avian tectum

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Poverty and limited attention

In this article, we analyze whether the financial strain of poverty systematically alters the allocation of attention. We address two types of attention: attention to unexpectedly occurring events and attention to primary tasks that require focus. We show that the poor are significantly more likely than the rich to notice unexpected events. In addition, we do not find robust evidence that poverty increases the likelihood of noticing the unexpected events at the expense of attention to the primary task.     

Predicting the eye fixation locations in the gray scale images in the visual scenes with different semantic contents

In recent years, there has been considerable interest in visual attention models (saliency map of visual attention). These models can be used to predict eye fixation locations, and thus will have many applications in various fields which leads to obtain better performance in machine vision systems. Most of these models need to be improved because they are based on bottom-up computation that does not consider top-down image semantic contents and often does not match actual eye fixation locations. In this study, we recorded the eye movements (i.e., fixations) of fourteen individuals who viewed images which consist natural (e.g., landscape, animal) and man-made (e.g., building, vehicles) scenes. We extracted the fixation locations of eye movements in two image categories. After extraction of the fixation areas (a patch around each fixation location), characteristics of these areas were evaluated as compared to non-fixation areas. The extracted features in each patch included the orientation and spatial frequency. After feature extraction phase, different statistical classifiers were trained for prediction of eye fixation locations by these features. This study connects eye-tracking results to automatic prediction of saliency regions of the images. The results showed that it is possible to predict the eye fixation locations by using of the image patches around subjects’ fixation points.