抄録
It is known that most other animals than humans are unable to pass the symmetry test. Some authors of the Cognitive Studies, 15(3), pointed out that the arbitrary matching to sample task, a standard test for the symmetry, includes a time sequence of stimuli, which may cause a difficulty in reversing the relation between the sample stimuli and the comparison stimuli, and in passing the test. Moreover, the task requires ability to actively select a stimulus, which also may cause the difficulty. This paper hence proposes a simple test for symmetry which excludes additional obstacles in the test such as the time order between the stimuli, and also excludes the action of selection.
