Yu Deyue, Chung Susana T L
School of Optometry, University of California, Berkeley, Berkeley, California, USA.
Optom Vis Sci. 2011 Jun;88(6):724-32. doi: 10.1097/OPX.0b013e318213933c.
Difficulty identifying faces is a common complaint of people with central vision loss. Dakin and Watt (2009) reported that the horizontal components of face images are most informative for face identification in normal vision. In this study, we examined whether people with central vision loss similarly rely primarily on the horizontal components of face images for face identification.
Seven observers with central vision loss (mean age = 69 ± 9 [SD]) and five age-matched observers with normal vision (mean age = 65 ± 6) participated in this study. We measured observers' accuracy for reporting the identity of face images spatially filtered using an orientation filter with center orientation ranging from 0 (horizontal) to 150° in steps of 30°, with a bandwidth of 23°. Face images without filtering were also tested.
For all observers, accuracy for identifying filtered face images was highest around the horizontal orientation, dropping systematically as the filter orientation deviated from horizontal, and was the lowest at the vertical orientation. Compared with control observers, observers with central vision loss showed (1) a larger difference in accuracy between identifying filtered (at peak performance) and unfiltered face images; (2) a reduced accuracy at peak performance; and (3) a smaller difference in performance for identifying filtered images between the horizontal and the vertical filter orientations.
Spatial information around the horizontal orientation in face images is the most important for face identification, for people with normal vision and central vision loss alike. While the horizontal information alone can support reasonably good performance for identifying faces in people with normal vision, people with central vision loss seem to also rely on information along other orientations.
面部识别困难是中心视力丧失者的常见主诉。达金和瓦特（2009年）报告称，面部图像的水平成分对于正常视力者的面部识别最具信息价值。在本研究中，我们探究了中心视力丧失者在面部识别时是否同样主要依赖面部图像的水平成分。
七名中心视力丧失的观察者（平均年龄 = 69 ± 9 [标准差]）和五名年龄匹配的视力正常的观察者（平均年龄 = 65 ± 6）参与了本研究。我们测量了观察者报告经空间滤波的面部图像身份的准确性，该滤波使用中心方向从0（水平）到150°、步长为30°、带宽为23°的方向滤波器。还测试了未经过滤波的面部图像。
对于所有观察者而言，识别滤波后的面部图像的准确性在水平方向附近最高，随着滤波器方向偏离水平方向而系统地下降，在垂直方向最低。与对照观察者相比，中心视力丧失的观察者表现出：（1）识别滤波后（在最佳表现时）和未滤波的面部图像之间的准确性差异更大；（2）最佳表现时准确性降低；（3）识别水平和垂直滤波器方向的滤波图像时表现差异更小。
面部图像中水平方向周围的空间信息对于面部识别最为重要，无论是对于视力正常者还是中心视力丧失者。虽然仅水平信息就能支持视力正常者在识别面部时表现出相当不错的性能，但中心视力丧失者似乎还依赖其他方向的信息。
