In this paper, a “learning by observation” method, which is most commonly employed motion for learning, is examined. In the observation-based learning method, learners generally observe, recognize, and reproduce a model-performed reference motions only from one direction. Subjects can observe the model from various directions: the orientation of the model’s trunk doesn’t accord with that of the subjects when viewing from a direction other than from behind the model. It prevents the subjects from learning the model’s reference motions easily because the subjects need to rotate the model mentally (it is called the “mental rotation”). On the other hand, when viewing from behind the avatar in order to avoid the mental rotation cost, subjects would occasionally encounter occlusion problems. Therefore, we have studied perceptual characteristics of various observation views through a psychophysical experiment. Two kinds of physical values were employed for evaluating subject’s responses. One is the delayed time for reproduced motion onset, and the other is the error rate of reproduced motion direction. The results suggest that the perception suffers ill-effects from the mental rotation in two ways: the amount of the mental rotation increases the delayed time, and the presence of the mental rotation does the directional errors.