Movement planning in prehension: do intended actions influence the initial reach and grasp movement?

In three experiments the influence of different consecutive movements on an initial reaching and prehension movement was examined. These so-called after-grasp movements, defined as movements following a prehension movement towards an object, were lifting and raising the object, throwing the object in a bin, and positioning it accurately on a target location. Three different groups of participants (N1 = 8, N2 = 10, N3 = 10) accomplished the lifting and one of the three other after-grasp movements each with three different object sizes and with the left and the right hand. In total, each participant executed 240 trials. Fourteen movement parameter values were examined to analyze the effects of the after-grasp movements on the initial reach and grasp movement. The results showed that movement parameter values of the initial reach and grasp movement were affected differently depending on the type of consecutive movement. In particular, the deceleration phase prior to object contact differed between movement types.