The document summarizes the bubble cursor, a target acquisition technique that dynamically resizes the cursor activation area based on the proximity of surrounding targets. This improves pointing performance by effectively increasing the width of targets and reducing acquisition times compared to a standard point cursor. The bubble cursor algorithm continuously updates the radius to match the minimum distance between the closest and second closest targets, ensuring only the closest target can be selected. The authors implemented the bubble cursor as a context menu with circular targets around the cursor, with selection occurring by left-click when a target is in focus.

1. THE BUBBLE CURSOR
Introduction to Human-Computer Interaction
Craig Kershaw & Francesco Bonadiman

2. THE CONTEXT
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Paper by T. Grossman and R. Balakrishnan
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CHI 2005 Best Paper Award Winner
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Target acquisition technique
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Dynamically resizes cursor activation area
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Depends on proximity of surrounding targets
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Only one target is selectable at any time
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3. THE MOTIVATION
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Improvements in pointing performance
 significant impact on usability
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Attempts to beat Fitts’ Law
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By dynamically increasing the target width
 Reduces target acquisition times
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Performance equivalent to point cursor selecting
targets with size as bubble radius width
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4. SQUARES VS. CIRCLES
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Circles always captures the closest target first
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5. A SIMPLE ALGORITHM
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Continuously updates the radius of the bubble
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Minimum distance between:
 Furthest point of the closest target
 Nearest point of the second closest
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6. OUR IMPLEMENTATION
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Implemented as bubble context menu
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Right-click on item  bubble cursor activation
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Circular targets surrounding cursor
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7. OUR IMPLEMENTATION
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Facilitate access of most frequent items
 Like “bubbling menus”
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Size depending on frequency of clicks
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Left-click to select the item in focus
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New right-click to close
 Selecting becomes instinctive
 Gesture-like
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8. DEMO
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Thank you!