尽管对于Wheatstone-Panum极限情况的特征匹配方式存在争议,但通常认为,两眼中特征数目都为2的常规立体视下的特征匹配遵循惟一性原则.本研究采用简单的2∶2直线型常规立体视构型发现,在左右直线分别发生融合的情况下,被试者可观察到第3根直线,这一现象与惟一性原则相背.利用双眼性探针技术证明,这根直线的产生,是由于一只眼中的某根直线与对侧眼中的两根直线发生了双重融合,这一结果表明,常规立体视并非只发生惟一性融合,还可能发生双重融合,并提示,Wheatstone-Panum极限情况发生的是双重融合.
Although there exists disputation about the matching manner of the features in the Wheatstone-Panum limiting case, it is generally considered that the uniqueness constraint operates in the conventional stereopsis condition when there is an even number of two features within corresponding binocular regions of each eye. By using a simple two to-two line-type conventional stereoscopic configuration, it was found that subjects could observe a third line un- der the condition when the left and the right line in one eye separately fuse with the left and the right line in the other eye, thus a phenomenon apparently violates the uniqueness constraint. By adopting two pairs of stereoscopic probes, we demonstrated that the extra line resulted from double fusion occurred between one line in one eye and two lines in the other eye. These results indicate that double fusion as well as single fusion may occur under the conventional stereopsis condition, and they imply that double fusion occurs in the Wheatstone-Panum limiting case.