TRANSMISSION OF INFORMATION IN VISUAL SYSTEM

现有的结果表明，字母识别是由特征介导的 （Pelli，Burns，Farell和摩尔，1996）。 特征是带限的， 利用与空间频率信道相同的调谐（所罗门和佩利， 1994），并且它们是简单的（Pelli等人，1966年）。 这符合 流行的观点认为，功能就像是面向中心-环绕接收 场或小波。 我们建议： 在空间和空间频率中使用临界频带掩蔽， 识别介导视觉检测和识别的特征 使用候选特征对字母识别进行建模 人工和传统字母表的性能。 对这种方法的成功充满信心的一个原因是， 已经成功地模拟了单词识别性能， 字母作为候选特征，表明人类表现接近 但永远不会超过一个理想的观察者的表现， 根据独立的后一种鉴定作出决定。 取特征 比一个字母更小将使上限更低， 更严格的测试。 如果超过这个界限， 推测人类的表现是由独立的决定介导的， 这一系列的特点。 其他三个项目将使用字母和噪音： 表征介导弱视视力差的通道， 正常的中央凹和周边;（试点数据表明，我们的最后一个通道 假设可以解释字母敏锐度。） 测量周边等效噪声，并与 基于神经节细胞噪声的生理测量的预测; 进行与我们的测量平行的对比度反应的fMRI测量 字母识别的效率。

Results in hand tell us that letter identification is mediated by features (Pelli, Burns, Farell, and Moore, 1996). The features are bandlimited, with the same tuning as a spatial-frequency channel (Solomon and Pelli, 1994), and they are simple (Pelli, et al., 1966). This is consistent with the popular idea that features are like oriented center-surround receptive fields, or wavelets. We propose to: to use critical band masking in space and spatial frequency to identify the features that mediate visual detection and identification to use the candidate features to model letter identification performance with artificial and traditional alphabets. One reason for confidence in the success of this approach is that we have already succeeded in modeling word identification performance, taking letters as candidate features, showing that human performance approaches but never exceeds the performance of an otherwise-ideal observer that must base its decisions on independent latter identifications. Taking features to be smaller than a letter will bring the upper bound still lower making an even more stringent test. Exceeding that bound would disprove the conjecture that human performance is mediated by independent decisions on that set of features. Three other projects will use letters and noise to: characterize the channel mediating the poor acuity in amblyopic and normal fovea and periphery; (Pilot data indicate that our last-channel hypothesis may explain letter acuity.) measure equivalent noise in the periphery and compare it with predictions based on physiological measurements of ganglion cell noise; make fMRI measurements of contrast response paralleling our measure of efficiency of letter identification.