视觉工作记忆对前注意阶段注意定向的调节

在注意阶段,视觉工作记忆与注意共享某些特征时,视觉工作记忆内容会引导注意定向。在前注意阶段的影响又是如何？对此问题的研究却很少见,本研究采用工作记忆与基于特征的视觉搜索相结合的任务深入探讨了此问题。研究结果发现：即使在前注意阶段,注意定向也会受到视觉工作记忆自上而下的调节。然而与注意阶段不同的是：当视觉工作记忆内容与随后视觉搜索任务的目标相关时,与记忆内容匹配的搜索项目会引导注意定向到该项目所在的位置,但只有此项目作为分心物时,才会明显地延迟对靶子的加工,而此项目作为靶子时,这种影响并不明显;当视觉工作记忆中保持的项目与随后视觉搜索任务的目标无关时,注意会忽略视觉工作记忆中保持的项目,有效地检测靶子     

眼睛注视是独特的吗?——来自发展的证据

采用改编的Posner视空间线索化任务,考查6~9岁儿童对眼睛注视、手指指向、箭头指向和代向汉字4种中央线索的注意定向。结果发现,6岁儿童已经能对眼睛注视线索进行注意定向,并随着年龄增长而改善。7岁组和8岁组儿童注意定向的成绩显著改善,7岁可能是儿童对中央线索注意定向发展的特定阶段。而对手指指向和箭头的注意定向,只有8岁和9岁儿童表现出来。对代向汉字线索的注意定向,8岁时开始出现,9岁时表现出显著的提高。结果提示,眼睛注视线索可能是一种独特的视觉线索,有别于其他中央线索引发的注意定向的发展。     

Sub-threshold cuing: Saccadic responses to low-contrast,peripheral, transient visual landmark cues

Dorsal stream visual encoding was studied in three experiments, by examining effects of peripheral landmark cues on eye movements. Stimulus features and task structure were tailored to physiological and functional characterisations of the dorsal visual stream. Sub-discriminable peripheral stimuli served as landmark cue stimuli. In Experiments 1 and 2, orienting behaviour in response to cues and targets differed for participants with relatively low and relatively high peripheral contrast thresholds. In Experiment 1, low, but not high-threshold participants oriented towards landmark cues that could not be discriminated consciously. However, in Experiment 3, high-, but not low-threshold participants oriented towards near threshold cues. Hence, under appropriate conditions both groups of participants oriented in response to brief, low-contrast, peripheral information. We propose that landmark cueing may provide a useful tool for measuring individual differences in dorsal stream processing and dynamic aspects of visual functioning and awareness.     

Where is the chocolate? Rapid spatial orienting toward stimuli associated with primary rewards

Some stimuli can orient attentional resources and access awareness even if they appear outside the focus of voluntary attention. Stimuli with low-level perceptual salience and stimuli with an emotional content can modulate attention independently of voluntary processes. In Experiment 1, we used a spatial cuing task to investigate whether stimuli that are controlled for their perceptual salience can modulate the rapid orienting of attention based exclusively on their affective relevance. Affective relevance was manipulated through a Pavlovian conditioning paradigm in which an arbitrary and affectively neutral perceptual stimulus was associated with a primary reward (i.e., a chocolate odor). Results revealed that, after conditioning, attentional resources were rapidly oriented toward the stimulus that was previously associated with the reward. In Experiment 2, we used the very same conditioning procedure, but we devaluated the reward after conditioning for half of the participants through a sensory-specific satiation procedure. Strikingly, when the reward was devaluated, attention was no longer oriented toward reward-associated stimuli. Our findings therefore suggest that reward associations rapidly modulate visual processing independently of both voluntary processing and the perceptual salience of the stimulus. This supports the notion that stimuli associated with primary rewards modulate rapid attention orienting on the basis of the affective relevance of the stimulus.     

Orienting of attention: Then and now

It is nearly 35 years since I gave the 7th Sir Frederick Bartlett lecture at Oxford University. This was published as a paper entitled “Orienting of attention in the quarterly journal”. The topic was then primarily in psychology, but now equally often in neuroscience. This paper summarizes the background of the reaction time methods used in the original paper and findings that emerged later on the sensory consequences of orienting, mainly in the visual system. It then discusses the brain network that is the source of the sensory amplification and other brain networks that are involved in attention. Next, it reviews studies of the development of attentional networks in early life. Finally, it indicates how the new tools available to explore the human brain can lead to further progress.     

Exogenous attention to angry faces in social anxiety: A perceptual accuracy approach

We investigated the interaction between endogenous and exogenous attention for the processing of emotional stimuli in individuals with high social anxiety using accuracy rates. Following the presentation of an endogenous cue at the centre, exogenous cues (i.e., angry and neutral faces) were presented at peripheral locations. Subsequently, non-emotional masked targets were presented, and the participants were instructed to discriminate between the targets. With respect to exogenous attention, high socially anxious people exhibited higher accuracy when the angry face and target appeared on the same side than when they appeared on different sides, whereas low socially anxious people did not exhibit such effects. On the other hand, different abilities of endogenous attention were not observed between high and low socially anxious people. These results suggest that exogenous attention is biased towards threat in high socially anxious people.     

Testing the dorsal stream attention hypothesis: Electrophysiological correlates and the effects of ventral stream damage

The roles of dorsal and ventral processing streams in visual orienting and conscious perception were examined in two experiments. The first employed high density EEG with source localization. The second comprised a neuropsychological case study. Visual orienting was assessed with an attention procedure, where peripheral letters cued participants towards a target location. In the perception procedure participants responded to the same letters by performing an explicit conscious discrimination. In Experiment 1, the peripheral letters elicited rapid dorsal stream activation in the attention procedure, and this activation preceded top-down enhancement of target processing in occipital cortex. In the perception procedure early ventral stream activation was seen. In addition, peripheral letters elicited an “early directing attention negativity” (EDAN) over parietal recording sites in the attention procedure, but not in the perception procedure. In Experiment 2, a patient with a bilateral ventral stream lesion but preserved dorsal stream function showed clear disruption to performance in the perception procedure, whilst exhibiting a normal visual orienting effect in the attention procedure. Taken together these findings (1) highlight the distinct roles of the dorsal and ventral streams in attention and perception, and (2) suggest how these streams might interact, via reentrant effects of attention on perceptual processing.     

Resolving conflicting views: Gaze and arrow cues do not trigger rapid reflexive shifts of attention

It has become widely accepted that the direction of another individual's eye gaze induces rapid, automatic, attentional orienting, due to it being such a vital cue as to where in our environment we should attend. This automatic orienting has also been associated with the directional-arrow cues used in studies of spatial attention. Here, we present evidence that the response-time cueing effects reported for spatially nonpredictive gaze and arrow cues are not the result of rapid, automatic shifts of attention. For both cue types, response-time effects were observed only for long-duration cue and target stimuli that overlapped temporally, were largest when the cues were presented simultaneously with the response-relevant target, and were driven by a slowing of responses for invalidly cued targets rather than speeding for validly cued ones. These results argue against automatic attention-orienting accounts and support a novel spatial-incongruency explanation for a whole class of rapid behavioural cueing effects.     

Effects of spatial cues on locating emotional targets

Inhibition of return (IOR) refers to slower responding to a visual target appearing at a previously cued versus uncued location. In three experiments, we asked whether IOR would be affected by the emotional content of target stimuli. Participants reported the location of negative (spiders, angry faces) or neutral (objects, neutral faces) targets as quickly and accurately as possible after a valid or invalid location cue (a simple circle). IOR was significantly smaller when detecting negative versus neutral targets, but only after repeated exposures to these stimuli (i.e., with blocked presentations). This effect was eliminated when target type was randomized within blocks. By presenting negative versus neutral targets in short alternating blocks and examining IOR on the first trial of each new block, we show that the emotional modulation of IOR stems from the affective context in place before visual orienting is initiated, not by perceptual processing of the target after cue offset.     

错误后减慢理论模型述评

错误后减慢是指错误后正确反应与正确后正确反应相比反应时显著延长的现象.目前研究者已经发现错误后减慢、错误后正确率提高以及错误后干扰效应减少三种错误调控行为,其中错误后减慢是最稳定的错误后行为表现.早期研究主要从冲突监控理论、激活抑制假说、强化学习理论和失匹配理论等角度解释该现象,近年来,研究者又提出了注意朝向理论和评估适应假说.对于该领域未来的研究可以从错误类型、无意识加工、个体差异、新的分析技术的运用方面考虑,以便全面揭示错误后减慢现象的本质.