to hand movements during manipu-
lation. We designed and evaluated a
technique called scaled HOMER38 in
an attempt to address this problem.
Scaled HOMER uses a large scaling
factor when the user’s hand is mov-
ing quickly, which allows for long-
distance object manipulation, but ap-
plies a small scaling factor when the
user’s hand is moving slowly, which
allows for very precise manipulation.
The nice thing about this mapping is
that users naturally move faster when
they are trying to move an object large
distances, and naturally slow down
when they are trying to be precise.
Thus, the technique has the same nat-
ural feel as the original HOMER, while
improving precision. This technique
is an example of adding enhance-
ments that can aid the user in task
performance without a reduction in
perceived naturalism.

Figure 2. user manipulating letter shapes in the selection and manipulation experiment. 22

Figure 3. Playing a first-person shooter game in the DiVe.

specific tasks. One such study took place in the context of a racing game (see McMahan21 for complete details). Motivated by the success of the Ninten-do Wii, we looked for a game that provided multiple interaction techniques at different levels of interaction fidelity for the same task. Mario Kart Wii, a popular racing game, proved to be useful for this purpose.

In Mario Kart, the primary task is steering a vehicle around a track. Since the game franchise has had versions on several prior consoles, it has well-designed traditional controls using a thumb-controlled joystick for steering. The Wii version continued to provide these controls, but also added the option of using the Wii Remote (sometimes embedded in a plastic steering wheel) for more natural steering control.

Our experiment compared four different steering techniques: two traditional techniques (based on slightly different controllers) and two natural techniques (Wii Remote with and without the wheel prop). To remove the influence of game AI, we used the “Time Trial” mode, which simply measures lap times without any other racers on the course and without random power-ups.

The results showed the less natural, joystick-based techniques were faster and more accurate. Players were able to drive more precisely using a less natural interface. At a high level, there could be several explanations for this result. We could conclude that increased interaction fidelity is harmful to performance for steering tasks, but we think it is more likely the Wii Remote-based techniques were not natural enough. The Wii Wheel is not mounted to a fixed base—the user holds it in mid-air— and it also provides no force-feed-back or re-centering as a real steering wheel would. In addition, the Wii Remote has some latency that may cause players to oversteer. Another interpretation is that the joystick-based techniques are actually more precise for the task of steering. This is an intriguing possibility, since it is known that small muscle groups such as those in the hand can be faster and more precise than the large muscle groups used to turn a steering wheel. 40 Per-