Stephens B R, Banks M S
Department of Psychology, Clemson University, South Carolina 29634.
J Exp Psychol Hum Percept Perform. 1987 Nov;13(4):558-65. doi: 10.1037//0096-1523.13.4.558.
The ability to detect differences in spatial contrast is crucial to object recognition and identification. This ability is generally examined by measuring the contrast discrimination function. This function represents, for a variety of conditions, the smallest contrast difference required to discriminate otherwise identical patterns. We examined human infants' ability to discriminate patterns on the basis of differences in spatial contrast. The forced-choice preferential looking procedure was used to estimate contrast increment thresholds at a number of background contrasts. The Weber fractions of 6- and 12-week-old infants were about 1 log unit higher than adult values for background contrasts ranging from 0.14 to 0.55. Furthermore, the slopes of infants' discrimination functions were much shallower than those of adults. These age differences in contrast discrimination imply certain changes in the neural mechanisms that underlie contrast encoding. They also aid our understanding of the anomalies observed in early pattern vision.
检测空间对比度差异的能力对于物体识别和鉴定至关重要。这种能力通常通过测量对比度辨别函数来检验。该函数针对各种条件表示辨别其他方面相同图案所需的最小对比度差异。我们研究了人类婴儿基于空间对比度差异辨别图案的能力。采用强迫选择优先注视程序来估计在多个背景对比度下的对比度增量阈值。对于背景对比度在0.14至0.55范围内，6周和12周大婴儿的韦伯分数比成人值高约1个对数单位。此外，婴儿辨别函数的斜率比成人的要平缓得多。对比度辨别方面的这些年龄差异意味着对比度编码背后的神经机制存在某些变化。它们也有助于我们理解早期图案视觉中观察到的异常情况。
