Abstract
We examined whether humans apply body images to non-human objects using mental rotation tasks. In Experiment 1, participants did mental rotation tasks in three conditions: a letter, a human-hand, and a monkey-hand. In the images of the letter, “F” and “R” were presented either in canonical or mirror images in different orientations. In the images of the human-hand, color pictures of a pointing or a grip shape were used as the stimuli. In the images of monkey-hand, pictures of a pointing or a grip shape taken from an anesthetized rhesus monkey were used as the stimuli. In Experiment 2, pictures of a pointing or a grip shape of a black glove were used instead of the monkey-hand. In the images of the letter, the pattern of the reaction time (RT) were symmetrical at the peak of 180 degrees, but those of the other images (i.e., human-hand, monkey-hand, and glove) were not symmetrical, which suggests the effect of biomechanical constraints. In addition, the peak of the RT in the human-hand shifted at 135 degrees to the right hand picture and at 225 degrees to the left hand one. These results suggest that humans tend to receive physical constraints when they mentally rotate not only images of a human hand but also images of a non-human object such as monkey hands and gloves. However, the constraints were not as strong as those of human hand.
