Object- and direction-specific interference between manual and mental rotation.

We conducted a series of psychophysical experiments to investigate the nature and specificity of behavioral interference between mental and manual rotation. Participants were asked to mentally rotate five different types of visual stimuli--hands, faces, tools, cubes, and natural objects--either clockwise or counterclockwise while they simultaneously manually rotated a wheel in the concordant or discordant direction. Our study clearly revealed object-specific interference between manual and mental rotation. In comparison with a neutral baseline condition without any manual rotation, both manual rotation directions generally impaired the mental rotation of cubes. In contrast, the mental rotation of hands was impaired only by discordant manual rotation. This object- and direction-specific interference between manual and mental rotation proved to be independent of task difficulty. We furthermore found an angular distance effect across different stimulus types.