With the development of eye-tracking technology,
various eye-gaze interfaces have been explored in the field of human-computer interaction.
Pointing to and selecting targets are the primary tasks of the eye-gaze interface.
However, it is difficult to select small targets using the eye-gaze interface,
as the human eye is constantly in motion, and precise manipulation is challenging.
We introduce another combination of the eye-gaze interface and an area cursor technique,
to support the small target selection task in a mouse.
Area cursors support small target selection using a mouse and display.
Our key principle is that the area cursor technique can enhance eye-gaze interaction because
it can decrease movement time in the eye-gaze interface unlike in a mouse-based interface.
We presented two methods, one is Bubble Gaze Cursor, and another one is Bubble Gaze Lens.
The Bubble Gaze Cursor technique is a combination
of the Bubble Cursor technique and the eye-tracking interface.
The Bubble Cursor is a circular area cursor in a mouse that keeps changing
the cursor size dynamically to always contain only one target.
A bubble cursor expands the target width to the bubble cursor radius.
This video shows a user actually using the Bubble Gaze Cursor.
The Bubble Gaze Lens technique is a combination of the Bubble
Lens technique and the eye-tracking interface.
The bubble cursor performs poorly when targets are small and densely packed.
Bubble Lens is a technique for enlarging a small target by activating a magnifying lens
when the mouse cursor is close to the goal target and selecting it easily and quickly.
A pointing movement consists of a ballistic movement and one or more corrective sub-movements.
Bubble Lens's algorithm is an algorithm for detecting corrective sub-movements.
After saccade which is rapid eye movement, secondary saccades sometimes occur.
So, we implemented Bubble Lens in the eye-gaze interface by detecting the secondary saccades.
This video shows a user actually using the Bubble Gaze Lens.
In this work, we conduct two studies to measure the performance,
usability, and workload of two techniques.
The first study investigates the performance and usability of the bubble gaze cursor technique.
So, we compare three interfaces, Bubble Mouse,
Point Gaze, and Bubble Gaze. A total of 18 participants were enrolled.
Dependent variables are movement time and error rate.
Bubble Mouse is the original bubble cursor technique.
Unlike the other methods, the object is selected with the mouse, not with the eye gaze.
Point Gaze is a standard target selection method featuring an eye-gaze interface.
The shape of the cursor is a point, and when the cursor dwells inside an
object for a certain period of time, the object is selected.
Bubble Gaze is our proposed technique,
in which we combined a bubble cursor with an eye-gaze interface.
There were four independent variables, Cursor Type,
Amplitude, Target Width, and Effective Width.
The independent variables A are 350, 550, and 800 pixels, TW are 50, 65, 80 pixels, and EW are 100,
120, 140 pixels. The 1 pixel is 0.33mm.
The result of study #1 showed the bubble gaze cursor was significantly faster than the standard
point cursor-based eye-gaze interface. However, the cursor was significantly
slower than the original cursor technique that featured a mouse.
The error rate of Bubble Mouse and Bubble Gaze increased when
the targets were large but were only 1.0-3.0%.
Next, we conduct a study #2 to investigate the performance and
usability of the bubble gaze lens technique.
In this study, we compare two interfaces, Bubble Gaze Cursor and Bubble Gaze Lens.
A total of 20 participants were enrolled. Dependent variables are movement time,
error rate, System Usability Scale, and NASA task load index questionnaires.
Although Bubble Cursor works well when a target is surrounded by empty space,
it degenerates to a point cursor when a target is densely packed alongside other targets.
The Bubble Gaze Lens solves this shortcoming by using a magnifying lens to enlarge the target.
There were four independent variables, Cursor Type, Distance between gaze and
target centers, Target Width, and Spacing. The independent variables D are 350, 550,
and 800 pixels, TW are 20, 30, 52 pixels, and S are No Spacing, Half-target Spacing,
Full-target Spacing. The 1 pixel is 0.27mm.
We used an effective width for data visualization. EW can be calculated as a combination of TW and S.
Thus, the nine EWs were 20, 25, 30, 32, 40, 48, 52, 65, and 78 pixels.
These EWs are almost smaller than the required target size of eye-gaze interface.
This video shows a user actually using the Bubble Gaze Cursor in experiment.
It can be seen from the video that selecting a small,
dense target is difficult with the Bubble Gaze Cursor technique.
This video shows a user actually using the Bubble Gaze Lens in experiment.
It can be seen from the video that the magnifying lens magnifies the small target,
making it easier to select.
The result of study #2 showed Bubble Gaze Lens was faster than Bubble Gaze Cursor.
Bubble Gaze Lens was more accurate than Bubble Gaze Cursor for all combinations
of independent variables. Bubble Gaze Lens reduced the error rate by 54.0%.
Bubble Gaze Lens got significantly better
SUS scores and NASA-TLX overall score than Bubble Gaze Cursor.
As a conclusion, we conducted two studies to explore how area cursor
techniques contribute to eye-gaze interfaces. Results indicated that the bubble gaze cursor
was significantly faster than the standard point cursor-based eye-gaze interface.
And, the bubble gaze lens was faster than the bubble gaze cursor for all
combinations of independent variables, and reduced the error rate by 54.0%.