Interference in sequential grasping: Effects of action and perception


Past research has shown strong evidence supporting the notion that the visual control of action and the visual perception of objects are mediated by two functionally and anatomically distinct visual systems (Milner & Goodale, 2008). Little is known about how each visual system interferes with the other when performing a sequential task. However, it is known that the kinematics during the performance of an action can be interfered by a subsidiary perceptual task (Castiello, 1996). In the current study participants were presented with two rectangular objects placed one in front of the other. Participants were instructed to grasp the first object and place it on a specified target area and then either grasp (action condition) or make a perceptual judgment (perception condition) about the second object.  Participants’ peak grip aperture, movement time and reaction time to the first object were measured via 3D motion capture (OPTOTRAK 3020 system). The results revealed that preparing an action to the second object does not produce interference on the first action, but attending to its size for judgment does. Specifically, as the size of the second object increased, the amplitude of peak grip aperture and movement time towards the first object was also increased when performing the verbal perception condition. However, this pattern of interference was not shown when performing the action condition.