Haptic feedback provides an additional interaction channel when auditory and visual feedback may not be appropriate. We present a novel haptic feedback system that changes its elasticity to convey information for eyes-free interaction. SqueezeBlock is an electro-mechanical system that can realize a virtual spring having a programmatically controlled spring constant. It also allows for additional haptic modalities by altering the Hooke's Law linear-elastic force- displacement equation, such as non-linear springs, size changes, and spring length (range of motion) variations. This ability to program arbitrarily spring constants also allows for "click" and button-like feedback. We present several potential applications along with results from a study showing how well participants can distinguish between several levels of stiffness, size, and range of motion. We conclude with implications for interaction design.
Scrolling is an essential part of our everyday computing experience. Contemporary scrolling techniques rely on the explicit initiation of scrolling by the user. The act of scrolling is tightly coupled with the user?s ability to absorb information via the visual channel. The use of eye gaze information is therefore a natural choice for enhancing scrolling techniques. We present several gaze-enhanced scrolling techniques for manual and automatic scrolling which use gaze information as a primary input or as an augmented input. We also introduce the use off-screen gaze-actuated buttons for document navigation and control.