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注意时时影响着我们选择性地感知认识这个世界，通常认为，注意选择受到个体的动机、任务目标和刺激本身的特征等多方面的影响。注意理论的主要问题之一是与当前任务无关的干扰物是如何影响空间注意的。注意选择的理论解释主要分为两大阵营。一种理论认为，注意捕获是由刺激本身所具有的奇异的特征引起的，又被称为自下而上的或者刺激驱动的注意捕获。例如，突然出现的新客体C abrupt onset)或者特征单子(feature singleton)就会自下而上地捕获注意。另一种理论认为，注意捕获是受到自上而下的控制的，只有符合注意控制定势的干扰物才会捕获注意，又被称为关联注意捕获(contingent capture。这种关联捕获理论与生活和作业中的实际更贴近，也得到了认知和神经科学领域大量的实证研究的支持。然而以往针对关联注意捕获的研究全都关注需要执行操作的目标信号(即被试需要对这个刺激作出一个相应的反应)。人类对于需要执行的目标信号所建立的注意定势会自动捕捉注意，增强对于和目标信号匹配的刺激加工。但是，在生活中另一种十分重要的信号一一停止信号(被试接收到这个刺激之后需要取消和抑制一个反应)却没有得到研究者足够的关注。抑制反应的神经机制与选择性注意存在重叠，而停止信号既提示反应抑制，又需要得到选择性注意的加工，因此应当对于停止信号的注意定势进行研究。

停止信号在生活、生产中无处不在，与人们的安全、作业绩效等息息相关。典型的停止信号任务常被用于探索反应抑制的机制，在临床上，也与认知老化、物质成瘾、精神分裂症、注意缺陷多动障碍等密切相关。针对停止信号的研究多集中于行为抑制成功与否、自我监督等行为结果部分，而研究者们近期开始更为重视对停止信号前期加工的研究，例如，停止信号激活失败的可能性一直被忽视，这可能造成对停止信号行为结果的误读。因此研究基于停止信号特征的注意控制和选择加工机制尤为重要，本研究着力于增加停止信号注意定势的证据，以期丰富注意理论的框架，拓展加深对人类注意选择机制的理解认识。

本研究创新性地将视觉搜索任务和停止信号任务的结合起来研究了基于停止信号特征的注意捕获和眼动捕获(研究一)。结果发现，尽管停止信号色的干扰子与任务完全无关、出现的位置也在被试的搜索范围之外，仍会导致被试对目标刺激的反应时变长，并更大概率地吸引到被试的首次眼跳。这充分说明当无关刺激符合停止信号颜色特征时，可以自动捕捉注意和首次眼跳，干扰了对任务目标的加工。

本研究继续研究了符合停止信号特征的无关刺激的加工深度(研究二)、动作抑制倾向(研究三)，还将快速呈现序列范式和停止信号任务结合起来探索停止特征的脑神经激活(研究四)。研究二通过采用行为实验发现停止信号色的干扰子可以得到语义层次的自动加工，并且这种由停止信号特征诱发的自动语义加工与执行目标特征不同;研究三发现，停止信号色的干扰子没有引起个体在行为层面上更高的动作抑制率。但研究四发现停止信号色的干扰子相比于符合目标色的干扰子，激活了前额外侧(BA10 )和楔前叶等于动作控制有关的脑区，可以认为停止信号特征，即使与停止信号无关，也会激活个体自动执行控制和动作控制，这种影响主要体现在决策和冲突控制的阶段，损耗了更多的资源和时间。而停止信号特征与目标特征共同的激活在右侧海马、双侧颗枕联合区和双侧枕叶区域。

本研究探索了基于停止信号特征的注意捕捉、眼动捕捉、语义自动加工，反应抑制和脑激活。结果发现，停止信号的注意定势和目标的注意定势有相似的作用，即增强对相应特征颜色的加工，但停止信号的特征同时自动激活了执行控制有关脑区。这加深了我们对于选择性注意机制的理解，为注意理论研究加入了多样注意定势的证据，为研究反应抑制提供了一种崭新的视角和方法。

Attention helps us selectively feel and get to know the environment around us. Commonly, researchers believe that attentional selection is influenced by people’s motivation, the purpose of the ongoing task, as well as the feature of the stimuli. The main debate of attentional selection theories is on the question of how irrelevant distractor affects spatial attention. This debate is between two theories, bottom-up attention theory or stimuli-based capture and top-down attention theory contingent capture. The former one suggests that attentional capture is caused by the salient feature of a distractor. For instance, an abrupt onset or feature singleton can capture spatial attention. The latter one claims that, only when the feature of distractor meets with the definition of target, can it capture attention. This so-called contingent capture is more applicable when explaining the phenomenon in life and work. Contingent capture theory has been supported by many studies in cognitive psychology and neuropsychology. However, researchers were focusing only on a target that people should react on. They found that attention control set based on a target signal can capture attention, which will enhance the process of stimuli match the control set. Still there are important signals people should inhibit an up-coming response when they recognize them. The neural activation of response inhibition is overlapped with the neural activation of selective attention. And stop signal is a signal that suggests inhibition while it needs to be selected by attention, too. Thus, there is necessity to study the attention bias of stop signal.

Stop signals are ubiquitous in life. They are closely related to people's safety and performance, e.g. red traffic light. The classic stop-signal task has been used to study the mechanism of response inhibition. Clinically, dysfunction in the stop-signal task is also closely related to cognitive aging, substance addiction, schizophrenia, attention deficit hyperactivity disorder, and so on. Studies using stop signal task focused on behavioral results, such as rate of successful response inhibition, self-monitor of nonsuccessive inhibition, etc. Recently, researchers started to pay more attention to early processing stage of stop signal. For example, the possibility of stop-signal activation failure has been ignored, which may cause misinterpretation of the outcome of the behavior result. Thus, it is getting more important to work on attentional selection mechanism of stop signal. Our study focused on understanding mechanism of attentional control set of a stop signal, thus enriching the framework of attention theory, and expanding the understanding of the interaction mechanism between humans and the environment. What's more, this study provides new methods on studying the attentional process of the signals related to inhibition.

Our study creatively adopted compound paradigm of visual search task and stop signal task to examine the effect of irrelevant distractor which matches the attention control set of stop signal. In study 1，we explored the effect of attentional capture and eye movement capture. Results showed even an irrelevant stop-signal-featured distractor(as SSFD from here) appeared in positions totally independent with the ongoing visual search task, it still could prolong the reaction time of response towards the target, and capture the first eye saccade. This indicated that an irrelevant SSFD could automatically capture spatial attention and first saccade, thus interfered with the processing of task targets.

What' s more, we further studied the perceptual processing of the SSFD (study 2), motor inhibition tendency(study 3). And we adopted the compound paradigm of rapid serial visual presentation task and stop signal task to see brain cortex activation caused by the SSFD(study 4). In study 2, behavioral results showed that SSFD could be automatically processed on a semantic level. And this automatic semantic processing induced by the stop signal feature is different from the target feature. In study 3, we found that SSFD did not cause higher successful response inhibition rates at the behavioral level. However, in study 4, we found that compared to target-featured distractor, SSFD activated the frontopolar prefrontal cortex (BA10) related to executive control and precuneus (BA23) which is believed by researchers to be relevant with motor preparation and control. These results suggested that stop-signal feature, even if it obviously didn’t correlate with a stop signal at all, would trigger automatic executive control. This effect is mainly reflected in the stage of decision-making and conflict control, which consumes individuals more cognitive resources and time before they conduct any motor behavior.

This study explored the attentional selection mechanism of attentional control set of stop signal from different aspects such as attentional capture, eye movement capture, automatic semantic process, motor inhibition and brain cortex activation. It supplemented the attention theory and offered a new perspective and methodology of researching response inhibition.