Target Acquisition in Fish Tank VR: The Effects of Lag and Frame Rate

A study is reported of target acquisition in 3D using a head coupled stereo display and a hand tracking device. The effects of lag and frame rate were studied by introducing lag in three different ways: by queuing the hand input and delivering it to the cursor an integer number of frames later, by increasing the frame interval and sampling the input device at the start of the display interval, by increasing the frame interval and sampling the device close to the end of the display interval. The data suggests that a simple modification of Fitts' Law can account for system lag data, also that the main degradation of performance from low frame rate is due to the lag introduced and not to the disruption of perceptual processes.