Introduction
We often make reaching and grasping movements in cluttered environments consisting of both target and non-target items. The presence of non-target items in the surrounding alters the spatial trajectories of both reach-to-grasp (e.g. Howard and Tipper Since neither one’s own movements nor the behaviour of objects in the environment are completely predictable, it is important to be able to adjust ongoing reaching and grasping movements. We know that people make fast, automatic adjustments to account for changes in a target’s position (e.g. Brenner and Smeets Non-target items in the environment can also change position during reaching movements. Are positions of such items also continuously updated, allowing for fast adjustments of the ongoing movement? Aivar et al. (Thus, we know that one can respond to a change in obstacle position, but that this response differs from that to a change in target position. Does one consider the most recent information about obstacles when one responds to a change in target position? Chapman and Goodale (We used a virtual environment to find out whether the adjustment to an ongoing arm movement in response to a target jump considers the latest estimate of the positions of obstacles in the surrounding. We asked participants to slide their finger through a gap between two circular items. Half of the participants were told these items were obstacles and should be avoided, whereas the other half were told they were irrelevant. The reason for including irrelevant items was to check for direct responses to the obstacles’ motion because motion of irrelevant items can influence the finger’s path (e.g. Crowe et al. 