Time course of number magnitude interference during grasping.

In the present study, we recorded the kinematics of grasping movements in order to measure the possible interference caused by digits printed on the visible face of the objects to grasp. The aim of this approach was to test the hypothesis that digit magnitude processing shares common mechanisms with object size estimate during grasping. In the first stages of reaching, grip aperture was found to be larger consequent to the presentation of digits with a high value rather than a low one. The effect of digit magnitude on grip aperture was more pronounced for large objects. As the hand got closer to the object, the influence of digit magnitude decreased and grip aperture progressively reflected the actual size of the object. We concluded that number magnitude may interact with grip aperture while programming the grasping movements.