Identification of band-pass filtered letters and faces by human and ideal observers
Identification of band-pass filtered letters and faces by human and ideal observers
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DOI：
10.1016/s0042-6989(99)00080-2
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发表时间：
1999-10-01
期刊：
影响因子：
1.8
通讯作者：
Sekuler, AB
中科院分区：
文献类型：
--
作者：
Gold, J;Bennett, PJ;Sekuler, AB
为了更好地理解视觉系统在识别不同类型的复杂图案时如何利用跨空间尺度的信息，我们测量了人类和理想对比度识别阈值，以估计嵌入在二维动态高斯噪声中的1倍频和2倍频宽带通滤波字母和人脸的识别效率。刺激中心频率在1 ~ 70 c/对象范围内变化对字母和人脸识别效率的影响不同。在2倍频条件下，当中心频率从6.2 c/物体增加到49.5 c/物体时，字母和人脸的识别效率分别下降0.25 ~ 0.5和0.5 ~ 1.2个对数单位，而在中心频率低于6.2 c/物体时，只有字母可以被识别。在1倍频条件下，当中心频率从1.1 c/物体增加到2.2 c/物体时，字母识别效率增加了约0.5个对数单位，而在2.2 c/物体到35 c/物体时，字母识别效率几乎不变。在70摄氏度/物体时，人类观察者无法识别字母。令人惊讶的是，除了一个观察者8.8 c/物体，另一个观察者8.8 c/物体和17.5 c/物体外，人类观察者在所有中心频率下都无法识别人脸。在所有条件下，字母和人脸都获得了理想的观察者阈值，因此总是可以获得执行任务的信息。因此，不能识别人脸反映了视觉处理的限制，而不是缺乏刺激信息。选择性空间采样可以解释字母和人脸识别效率之间的一些差异。1999爱思唯尔科学有限公司版权所有。
To better understand how the visual system makes use of information across spatial scales when identifying different kinds of complex patterns, we measured human and ideal contrast identification thresholds to estimate identification efficiency for 1- and 2-octave wide band-pass filtered letters and faces embedded in 2-D dynamic Gaussian noise. Varying stimulus center frequency from 1 to 70 c/object had different effects on letter and face identification efficiency. In the 2-octave conditions, identification efficiencies decreased by 0.25-0.5 log units for letters and 0.5-1.2 log units for faces as center frequency increased from 6.2 to 49.5 c/object, but only letters were identifiable at center frequencies below 6.2 c/object. In the 1-octave conditions, letter identification efficiencies increased by about 0.5 log units as center frequency increased from 1.1 to 2.2 c/object, and were nearly constant from 2.2 to 35 c/object. Letters were unidentifiable by human observers at 70 c/object. Surprisingly, face identification was impossible for human observers at all center frequencies except 8.8 c/object for one observer, and 8.8 and 17.5 c/object for a second observer. Ideal observer thresholds were obtained for both letters and faces in all conditions, so information was always available to perform the task. Thus, the failure to identify faces reflects constraints on visual processing rather than a lack of stimulus information. Selective spatial sampling may account for some of the differences between letter and face identification efficiencies. (C) 1999 Elsevier Science Ltd. All rights reserved.