Hello everyone. My name is Huawei Tu. Today I'm going to talk about my work: distractor effects
on crossing-based interaction. Crossing is an important paradigm for mouse input,
stylus input and direct finger touch. Unlike classic point-and-click interactions,
the basic element of crossing interactions is to draw a stroke through the boundary of a target
to trigger an action. As we can see in the demo.
Crossing-based interface is a visual-spatial dependent gesture interface.
Targets provide visual stimuli so that users can comprehend spatial information to cross
the target. Let's take a look at the example on the right. Users draw a gesture to cross
some menu items to trigger actions. The gesture itself doesn't carry much information.
The expressiveness of crossing interactions doesn't rely on the stroke gesture. It
depends on graphical targets that the stroke gesture crosses on the interface.
In realistic interaction scenarios, intended targets are often surrounded by distractors.
Selecting these targets is a typical task on crossing-based interfaces.
The images show crossing-based interactions with distractors for checkboxes, radio buttons, dialog
boxes and menus in a goal-crossing framework. For example, when crossing item A in the checkbox,
item B could be a distractor. Existing fundamental studies of user performance in crossing tasks
generally didn't consider the presence of distractors around targets. Therefore we conducted
the first study to investigate distractor effects on crossing based interaction. This study focuses
on typical crossing based interfaces with items aligned horizontally or vertically. We adopted
six representative target–distractor spatial layouts in our experiment. We also developed six
quantitative models for these layouts. First let's take a look at direction-constrained crossing.
This is a layout without distractors. Two vertical targets are each crossed from left to right. We
used this layout as a baseline. We consider the distractors placed on the left of the target,
on the right of the target, and also on the left and right of the target.
Here we can see four amplitude-constrained crossing, which is to cross two horizontal targets
with downward strokes. We consider the layout without distractors,
distractors placed above the target, below the target and also above and below the target.
We conducted an experiment to investigate the effects of distractors on crossing-based
interaction. The independent variables were target-distractor spatial layouts,
target distance, target and distractor widths, and spacing between targets and distractors. The
dependent variables were completion time and error rates. We found that the presence of distractors
slowed down crossing interactions without significantly affecting target crossing accuracy.
When target-distractor spacing increased to 7.25 millimetres, its effects on selection time would
become insignificant. When spacing is smaller than 11.27 millimetres, crossing tasks with distractor
interference can be regarded as pointing tasks or combination of pointing and crossing tasks.
Regarding model fitting, compared to Fitts' law, our proposed models yielded better fits
with the experiment data in all six layouts with R square always greater than 0.95. Also our models
had smaller AIC than Fitts' law. Such results confirmed the advantage of our proposed models.
In this study, we carried out the first investigation into distractor effects
on crossing based interactions. We developed six models for six crossing tasks with distractor
interference. We also provided a set of general guidelines
and practical suggestions. That's the end of my presentation. Thank you.