The role of visual attention in action priming

It has been demonstrated that the task-irrelevant left-right orientation of an object is capable of facilitating left-right-hand responses when the object is orientated towards the responding hand. We investigated the role of attention in this orientation effect. Experiment 1 showed that object orientation facilitates responses of the hand that is compatible with the object's orientation, despite the entire object being irrelevant. However, when a task-relevant fixation point was displayed over the prime object in Experiment 2, the effect was not observed. Together Experiments 1 and 2 suggest that the orientation information of viewed objects primes the action selection processes even when the object is irrelevant, but only when attention is not allocated to a competing stimulus during the prime presentation. Experiment 3 suggested that the elimination of the effect in Experiment 2 could not be attributed to the elimination of an attentional shift to the graspable part of the prime. Finally, Experiment 4 showed that object orientation can evoke an abstract response code, influencing the selection of finger responses.