Attentional modulation of threshold sensitivity to first-order motion and second-order motion patterns
Attentional modulation of threshold sensitivity to first-order motion and second-order motion patterns
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DOI：
10.1016/j.visres.2003.07.005
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发表时间：
2003-12-01
期刊：
影响因子：
1.8
通讯作者：
Ledgeway, T
中科院分区：
文献类型：
--
作者：
Allen, HA;Ledgeway, T
先前的研究[例如，Vision Research 40（2000）173]已经表明，当要求观察者选择性地注意包含一阶（亮度定义的）或二阶（对比度定义的）运动的两个空间相邻的块中的一个时，用于识别二阶运动而不是一阶运动的方向的阈值灵敏度对于所注意的刺激被增强。因此，与一阶运动不同，二阶运动的处理可能需要注意。然而，其他研究几乎没有发现注意力对一阶和二阶运动处理的差异效应的证据[Investigative Ophthalmology and Visual Science 42（4）（2001）5061]。我们研究了注意指令对观察者识别亮度定义和对比度定义的运动刺激的方向和空间取向的能力的影响。同时呈现成对的运动刺激，并在宽范围的漂移时间频率和刺激持续时间内测量阈值性能。我们发现：（1）对于两种类型的运动，有注意运动刺激的方向辨别阈值均低于无注意运动刺激。当观察者事先不知道他们必须首先判断哪一片运动（有人或无人）时，这种影响的程度就会降低。(2)一阶运动的方向歧视同样受到影响，在所有的时间频率和持续时间检查，但二阶运动的注意力的影响严重依赖于漂移的时间频率和刺激持续时间。(3)方向歧视表现出很小或没有影响的注意指令。因此，注意力是否影响二阶运动的处理，关键取决于测试的精确刺激参数。此外，在适当的条件下，一阶运动的处理也受到注意的影响，尽管程度低于二阶运动。(C)2003爱思唯尔有限公司。保留所有权利。
Previous studies [e.g. Vision Research 40 (2000) 173] have shown that when observers are required to selectively attend to one of two, spatially-adjacent patches containing either first-order (luminance-defined) or second-order (contrast-defined) motion, threshold sensitivity for identifying the direction of second-order motion, but not first-order motion, is enhanced for the attended stimuli. The processing of second-order motion, unlike first-order motion, may, therefore, require attention. However, other studies have found little evidence for differential effects of attention on the processing of first-order and second-order motion [Investigative Ophthalmology and Visual Science 42(4) (2001) 5061]. We investigated the effects of attention instructions on the ability of observers to identify the directions and spatial orientations of luminance-defined and contrast-defined motion stimuli. Pairs of motion stimuli were presented simultaneously and threshold performance was measured over a wide range of drift temporal frequencies and stimulus durations. We found: (1) direction discrimination thresholds for attended motion stimuli were lower than those for unattended stimuli for both types of motion. The magnitude of this effect was reduced when the observers were not given prior knowledge of which patch of motion (attended or unattended) they had to judge first. (2) Direction discrimination for first-order motion was similarly affected at all temporal frequencies and durations examined, but for second-order motion the effects of attention depended critically on the drift temporal frequency and stimulus duration used. (3) Orientation discrimination showed little or no influence of attention instructions. Thus, whether or not attention influences the processing of second-order motion depends crucially on the precise stimulus parameters tested. Furthermore under appropriate conditions the processing of first-order motion is also influenced by attention, albeit to a lesser extent than second-order motion. (C) 2003 Elsevier Ltd. All rights reserved.