Both exogenous and endogenous covert spatial attention enhance contrast sensitivity, a fundamental measure of visual function that depends substantially on the spatial frequency and eccentricity of a stimulus. Whether and how each type of attention systematically improves contrast sensitivity across spatial frequency and eccentricity are fundamental to our understanding of visual perception. Previous studies have assessed the effects of spatial attention at individual spatial frequencies and, separately, at different eccentricities, but this is the first study to do so parametrically with the same task and observers. Using an orientation discrimination task, we investigated the effect of attention on contrast sensitivity over a wide range of spatial frequencies and eccentricities. Targets were presented alone or among distractors to assess signal enhancement and distractor suppression mechanisms of spatial attention. At each eccentricity, we found that exogenous attention preferentially enhanced spatial frequencies higher than the peak frequency in the baseline condition. In contrast, endogenous attention similarly enhanced a broad range of lower and higher spatial frequencies. The presence or absence of distractors did not alter the pattern of enhancement by each type of attention. Our findings reveal how the two types of covert spatial attention differentially shape how we perceive basic visual dimensions across the visual field.

译文

外源性和内源性隐蔽空间注意力都增强了对比敏感度,这是视觉功能的基本指标,基本上取决于刺激的空间频率和偏心率。每种类型的注意力是否以及如何系统地提高跨空间频率和偏心率的对比敏感度,是我们理解视觉感知的基础。先前的研究已经评估了空间注意在各个空间频率下以及分别在不同偏心率下的影响,但这是第一项针对相同任务和观察者进行参数研究的研究。使用方向判别任务,我们研究了在广泛的空间频率和偏心率范围内注意力对对比度敏感性的影响。单独或在干扰物中显示目标,以评估空间注意力的信号增强和干扰物抑制机制。在每个偏心率处,我们发现,在基线条件下,外源性注意优先提高了高于峰值频率的空间频率。相比之下,内源性注意力同样增强了广泛的较低和较高的空间频率。干扰物的存在与否不会改变每种注意力类型的增强方式。我们的发现揭示了两种类型的隐蔽空间注意力如何不同地塑造了我们在整个视野中感知基本视觉尺寸的方式。

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