Kiorpes L, Movshon J A
Center for Neural Science, New York University, New York 10003, USA.
Vision Res. 1998 Jan;38(1):61-70. doi: 10.1016/s0042-6989(97)00155-7.
The aim of this study was to evaluate the contribution of peripheral and central factors to the development of visual sensitivity. We used the approach of (Pelli, 1981, 1990) to evaluate the hypothesis that intrinsic noise is high in infants compared with adults, and therefore sets an important limit on contrast sensitivity in infants. We measured contrast thresholds in the presence of various levels of dynamic spatiotemporal broadband noise in infant monkeys, and evaluated the developmental changes in contrast threshold and intrinsic noise. Our data show that intrinsic noise is high in infants and falls with contrast threshold during development. However, contrast thresholds in high-contrast noise also fall during development, although by a smaller amount. Therefore, while changes in intrinsic noise set an important limit on the development of contrast sensitivity across spatial frequencies, changes in non-additive sources of noise also contribute, particularly at high spatial frequencies. We interpret these results in terms of Pelli's hypothesis about the sources of additive and non-additive noise affecting visual detection. In these terms, additive noise reflects peripheral factors and non-additive noise reflects central ones. Our results suggest that changes in peripheral sources of noise represent an important limit for the development of visual sensitivity.
本研究的目的是评估外周和中枢因素对视觉敏感度发展的贡献。我们采用了（佩利，1981年，1990年）的方法来评估这一假设，即与成年人相比，婴儿的内在噪声较高，因此对婴儿的对比敏感度设定了一个重要限制。我们在幼猴存在不同水平的动态时空宽带噪声的情况下测量了对比阈值，并评估了对比阈值和内在噪声的发育变化。我们的数据表明，婴儿的内在噪声较高，且在发育过程中随对比阈值下降。然而，高对比度噪声中的对比阈值在发育过程中也会下降，尽管下降幅度较小。因此，虽然内在噪声的变化对跨空间频率的对比敏感度发展设定了一个重要限制，但非加性噪声源的变化也有贡献，特别是在高空间频率时。我们根据佩利关于影响视觉检测的加性和非加性噪声源的假设来解释这些结果。从这些方面来看，加性噪声反映外周因素，而非加性噪声反映中枢因素。我们的结果表明，外周噪声源的变化是视觉敏感度发展的一个重要限制。
