The detection of mirror-symmetry structure projected on a frontal plane with the central projection method

Abstract

Many previous studies on symmetry perception indicated the importance of the intrinsic feature in mirror symmetry that the symmetry axis orthogonally bisects virtual lines between the symmetry pairs in detecting their 2-D mirror symmetry. In the present study, we used 2-D mirror symmetrical dot patterns on a plane in 3-D space which were rotated in depth and projected on a frontal plane with the central projection method. Using these stimuli, we investigated the validity of the above feature in the detection of 2-D symmetrical structure in 3-D space. The results showed that 2-D symmetry is detected quickly and exactly in many conditions even if the symmetrical patterns do not hold the above intrinsic feature. In addition, the results of our experiments indicated that symmetry axis has some effects on detection of 2-D symmetry pattern in 3-D space as in the case of the usual 2-D symmetry detection.