HOW DOES ATTENTION ALTER APPEARANCE? PSYCHOPHYSICS AND NEUROPHYSIOLOGY

描述（由申请人提供）：视觉感知并不总是我们环境的真实表现。相反，视觉场景的处理受到注意力选择性分配的影响。在有人看管的地方，视觉更快、更准确，空间分辨率更高[1-11，回顾见12]。通过以牺牲无人值守的位置为代价，在有人值守的位置改进信息处理，注意力使我们能够最有效地利用视觉系统有限的资源。最近的研究表明，注意力不仅可以提高表现，还可以改变几种基本视觉特征的外观[13-22]。一些作者对这些发现的解释提出了批评，并提出了基于决策偏差的替代解释，即人们更有可能选择一个被注意的刺激，但不会以不同的方式感知它[23-26]。尽管这一说法已经被对照实验[13,15 -21]和实证回复[14,27,28]所反驳，但这个问题仍然存在激烈的争论。这种现象学经验的注意调节的生理基础尚不清楚。虽然神经元反应的增强解释了注意力的提高，但它并不一定意味着外表的改变。相反，刺激特征的出现通常与选择性调节这些特征的神经元群的活动有关，而误解则与它们的选择性变化有关。因此，外观的变化应该是由那些参与处理被注意刺激的神经元群的选择性变化所介导的。该研究将首次测试空间注意对基本视觉特征的神经元群体选择性的影响，从而将对理解空间注意的机制作出重大贡献。此外，它将为注意力是否真正调节外表这个问题提供一个明确的答案。我们将采用一种适应范式，在这种范式中，适应特定刺激特征的神经元群可以在心理物理范式中被选择性地定位，因此适应和注意的相互作用将揭示这些神经元是否介导了对外观的注意效应。然后，将使用功能磁共振成像（fMRI）范式中的适应性，在有注意和没有注意的情况下直接测量种群选择性[29]。之所以选择速度和空间频率分别作为背侧和腹侧流的两个例子，是因为注意调节速度[18,20]和空间频率[15,30]的出现，而且因为在早期视觉皮层中存在对速度和空间频率进行调节的神经元[31-38]。心理物理和功能磁共振成像研究的结果将为空间注意力如何改变外观提供融合和补充的证据。

DESCRIPTION (provided by applicant): Visual perception is not always a veridical representation of our environment. Instead, processing of the visual scene is influenced by the selective allocation of attention. Vision at an attended location is faster, more accurate, and of higher spatial resolution [1-11, for a review see 12]. By improving information processing at attended locations at the cost of unattended locations, attention allows us to make most efficient use of the visual system's limited resources. Recent studies show that attention not only improves performance but also alters the appearance of several basic visual features [13-22]. Some authors have criticized the interpretation of these findings and suggested alternative explanations based on a decisional bias, i.e., people are more likely to select an attended stimulus but do not perceive it differently [23-26]. Although this account has been counter-argued by control experiments [13, 15-21] and empirical replies [14, 27, 28], the issue is still hotly debated. The physiological basis of such an attentional modulation of phenomenological experience is not yet known. Whereas an enhanced neuronal response explains increased performance with attention, it does not necessarily imply a change of appearance. Instead, the appearance of stimulus features has often been associated with the activity of neuronal populations selectively tuned for these features, and misperceptions have been related to shifts in their selectivity [49]. Therefore, a change of appearance should be mediated by shifts in the selectivity of those neuronal populations involved in processing the attended stimulus. The proposed research will be the first to test effects of spatial attention on neuronal population selectivity for basic visual features and will thereby significantly contribute to understanding the mechanisms of spatial attention. Furthermore, it will provide a definitive answer to the question whether attention truly modulates appearance. An adaptation paradigm will be employed in which neuronal populations tuned to specific stimulus features can be selectively targeted in a psychophysical paradigm, so that an interaction of adaptation and attention will reveal if these neurons mediate the attentional effect on appearance. Then, population selectivity will be directly measured with and without attention using adaptation in a functional magnetic resonance imaging (fMRI) paradigm [29]. Speed and spatial frequency were chosen as two respective examples from the dorsal and ventral streams, because attention modulates the appearance of both speed [18, 20] and spatial frequency [15, 30] and because neurons tuned for both speed and spatial frequency exist in early visual cortex [31-38]. Results from both the psychophysical and the fMRI study will provide converging and complementing evidence for how spatial attention changes appearance. PUBLIC HEALTH RELEVANCE: The proposed research will further our understanding of the physiological basis and mechanisms of visual attention. Such basic research lays the foundation to develop clinical applications to treat attention-related disorders, for example unilateral neglect or Attention-Deficit Hyperactivity Disorder (ADHD).