Fixational eye movements predict visual sensitivity.
Fixational eye movements predict visual sensitivity.
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DOI：
10.1098/rspb.2015.1568
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发表时间：
2015-10-22
期刊：
影响因子：
--
通讯作者：
Roach NW
中科院分区：
文献类型：
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作者：
Scholes C;McGraw PV;Nyström M;Roach NW
在稳定注视期间，观察者以每秒1-2次左右的速率进行小的注视扫视。视觉刺激的呈现触发注视扫视率的双相调制-初始抑制，随后是一段时间的速率升高，随后返回到基线。在这里，我们表明，在被动观看，这种率签名是高度敏感的刺激对比度的微小变化。通过训练线性支持向量机对刺激存在或不存在的试验进行分类，我们直接将注视眼动的对比敏感度与个人的心理物理判断进行比较。分类准确性密切匹配的心理物理性能，并预测个人的阈值估计的偏差和总体误差小于使用特定特征的签名。分类器的性能对训练集（新的受试者和/或对比）的变化是鲁棒的，并且通过实际数量的试验获得了良好的预测准确度。我们的研究结果表明，视觉感知判断的敏感性和固视眼控制机制之间的紧密耦合。这就提出了一种可能性，即注视扫视可以提供一种新的和客观的手段来估计视觉对比敏感度，而不需要观察者做出任何明确的判断。
During steady fixation, observers make small fixational saccades at a rate of around 1–2 per second. Presentation of a visual stimulus triggers a biphasic modulation in fixational saccade rate—an initial inhibition followed by a period of elevated rate and a subsequent return to baseline. Here we show that, during passive viewing, this rate signature is highly sensitive to small changes in stimulus contrast. By training a linear support vector machine to classify trials in which a stimulus is either present or absent, we directly compared the contrast sensitivity of fixational eye movements with individuals' psychophysical judgements. Classification accuracy closely matched psychophysical performance, and predicted individuals' threshold estimates with less bias and overall error than those obtained using specific features of the signature. Performance of the classifier was robust to changes in the training set (novel subjects and/or contrasts) and good prediction accuracy was obtained with a practicable number of trials. Our results indicate a tight coupling between the sensitivity of visual perceptual judgements and fixational eye control mechanisms. This raises the possibility that fixational saccades could provide a novel and objective means of estimating visual contrast sensitivity without the need for observers to make any explicit judgement.