一阶运动和二阶运动方向辨别的知觉学习及传递性研究

为了明确视觉系统对一阶运动和二阶运动识别机制之间的相互关系，采用一阶运动和二阶运动的正弦光栅刺激，在旁中央凹对训练组(14名被试)进行运动方向辨别的知觉学习训练．通过比较训练前后的对比敏感度变化，并同对照组(11名被试)的结果比较后发现：a．在旁中央凹，一阶运动光栅方向辨别的训练提高了被试辨别一阶运动方向的能力，但是这种提高的效果却不能传递到二阶运动光栅的方向辨别任务当中；b．二阶运动光栅方向辨别的训练在提高被试二阶运动方向识别能力的同时，也提高了被试在一阶运动光栅方向辨别任务中的表现．这一训练效果的“非对称”传递现象提示，人的视觉系统中存在两种不同的机制分别用于感知一阶运动和二阶运动，但这两种机制并非截然不同，而是部分分离的．

Perceptual Learning and Transfer Study of First- and Second-order Motion Direction Discrimination

In order to investigate the interactions between first- and second-order motion perception systems, 14 adult subjects with normal or correct to normal visual acuity were recruited and divided into two groups. Then these two groups were trained, in their parafovea, to discriminate the direction of first- and second-order motion gratings respectively. The spatial frequency of the gratings used in study was fixed at 2 cycles/degree and the temporal frequency was fixed at 8 Hz during training. Contrast sensitivity of subjects in these two training groups for first- and second- order motion was measured before and after 7 days' training to estimate the effects of training. In addition, the differences between the two training groups(14 subjects) and another control group (11 subjects) were studied. The results showed that: 1) the training with first-order motion gratings can improve subjects' performance in first-order motion direction discrimination but the improvement can't be transferred to the performance in second-order motion task; 2) the training with second-order motion gratings can improve subjects' performance in both first- and second-order motion direction discrimination tasks. In conclusion, an " asymmetric transfer" occurred between the training effect of first- and second-order motion gratings. These results indicate that there are two mechanisms for perceiving first- and second-order motion respectively. However, they are not completely different from each other but only partly separated.