Department of Psychology, Vanderbilt University |
| Moving about the world seems to involve a process of keeping track of one's own location in space that interferes with the ability to track moving objects (Thomas & Seiffert, 2010, Cognition). Here, we manipulated visual cues to self-motion to determine whether the cost of self-motion on tracking could be eliminated. As in the previous work, participants tracked 3 red targets among 3 red distractors, all moving randomly within a confined region of a virtual environment, then responded to a target-or-distractor probe at the end of each trial. While tracking, participants stepped in place or walked in a quarter circle around the tracking region. For this experiment, we changed the background so that it was a gray, featureless ganzfeld and added 3 black dots to manipulate the visual cues to self-motion. When these black dots were stationary, tracking accuracy was higher for stepping (90% correct) than walking (77%), t(11) = 3.7, p <.005. This replicated our previous work showing that even when reliable visual cues are given, self-motion impairs object tracking. When the black dots moved randomly like the distractors, the same result was obtained (stepping = 92% and walking = 77%, t(11) = 3.7, p <.005). This result suggests that even when no stationary visual cues are present, updating from self-motion impairs object tracking. However, when the black dots guided self-motion by rotating along arcs concentric to the participant's motion, self-motion did not impair tracking (89.1% and 88.9%, t <1, ns). Interestingly, this was true whether the dots rotated in the same or opposite direction as the participants. As a whole, these data suggest that multiple object tracking and self-motion share a resource related to updating locations in space, but that visual guidance of self-motion can reduce the dependence on this resource. |