No abstract

Tightly-coupled interaction is shared work in which each person's actions immediately and continuously influence the actions of others. Tightly-coupled collaboration is a hallmark of expert behavior in face-to-face activity, but becomes extremely difficult to accomplish over distributed groupware. The main cause of this difficulty is network delay that disrupts people's ability to synchronize their actions with another person. In this paper we report on two studies that explore local lag as a way of reducing this problem. When applied to visual feedback, local lag synchronizes the visual environments of the local and remote clients, preventing one person from getting ahead of the other. We tested the effects of local lag in several delay conditions: we found that the technique significantly improved performance, and that users did not rate local lag as more difficult or frustrating to use. Our studies improve our understanding of local lag and of how it improves tightly-coupled interaction in distributed groupware.

Neurologically normal people tend to collide with objects on the right side more frequently than with objects located on the left side of space. This phenomenon could be attributable to pseudoneglect wherein individuals selectively attend to the left field. The current study investigated this effect using a virtual route-following task that was presented centrally, in the lower field, and in the upper field. Handedness was also examined. Fifty-two participants (four left handed) completed this task, and when presented in the lower field, more left-side collisions emerged. In the upper condition, this bias reversed direction to the expected rightward bias. In the central condition, there was no significant directional bias in collision behavior. An interaction between handedness and presentation condition indicated that left-handed participants experienced more right-side collisions in the central condition. Collectively, these results suggest that directional biases (i.e., left vs. right) in collision behavior are modulated by both location in the visual field (central, upper, or lower) and handedness.