Thinking with portals: revisiting kinematic cues to intention.

What we intend to achieve with our actions affects the way we move our body. This has been repeatedly shown for both, movement-related intentions such as grasping and turning an object, and relatively high-level intentions such as the intention to collaborate or to compete with a social partner. The impact of an intermediate level of intentions - referring to action-contingent changes in the physical environment - is far less clear, however. We present three experiments that aim at scrutinizing this level of analysis by showing how such anticipated consequences affect movement trajectories. Participants steered a virtual avatar toward portals that displaced the avatar to a different but predictable location. Even though this displacement occurred only after the movement was completed, hand movements were clearly torn toward the anticipated final location of the avatar. These results show that properties of anticipated action consequences leave a fingerprint on movement trajectories and provide an opportunity to unite previous accounts on the relation of intentions and movements with general frameworks of action planning.
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