Several theories of visual perception and visually-guided action make varying assumptions about the nature of the underlying cognitive representations. Often, the representations used in the early phase of action planning are assumed to be more abstract/amodal, while in the later control phase, they are assumed to be more concrete/modal. We will test these assumptions by using interference from a secondary task performed in parallel to a grasping task. The secondary task will be a memory test with either modal or amodal content which should interfere with grasping when the corresponding representations are of similar format. For example, an amodal secondary task might increase early parameters of a grasping movement, such as early grip aperture variance (EGAV) and reaction time (RT). In contrast, a modal secondary task might interfere with late parameters like maximum grip aperture variance (MGAV) and movement time (MT). Participants will be shown four stimuli at four different locations to memorize, then grasp an object, and then reproduce one of the four memorized stimuli. In the modal condition, memorized stimuli will be lines of different lengths. In the amodal condition, memorized stimuli will be numbers representing different line lengths. We expect larger EGAV and RT in the modal condition and larger MGAV and MT in the amodal condition. The outcome will be useful in determining whether the nature of representations changes during the course of an action.