"No one, to my knowledge, has suggested that the image must accelerate and decelerate or that the relation among torque, angular momentum, and angular velocity has a,1 analogue in the mental rotation case. Of course it may tum our that it takes subjects longer to rotate an object that they imagine to be heavier, thus increasing the predictive value of the metaphor. But in that case it seems clearer that, even if it was predictive, the metaphor could nor be explanatory (surely, no one believes that some images are heavier than others and the heavier ones accelerate more slowly)."