Most Virtual Reality applications involve manual manipulation and suffer from lags. Effects of lag in a virtual environment have received much attention. However, effects of target distance and width had not been analyzed in separation. A study has been conducted to investigate the effects of, and interactions among, hand movement related lag, target distance, and target width on manual task performance in a virtual environment. With a constant hand-related lag, hand Movement Time obeys Fitts' law (R2>0.85). Lags of 110 ms or above can significantly increase hand Movement Times and their effects have significant interactions with the effects of target width but not with target distance. This finding indicates that, in the presence of lag, the effects of target distance and width should be analyzed in separation.
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