James A. Landay, Jason Hong, Scott Klemmer, James Lin, and Mark Newman
The limitations of graphical user interfaces have slowed the spread of computer usage to the entire population. Perceptual user interfaces are one approach that can overcome many of these limitations. Adding perceptual capabilities, such as speech, sketching, and vision, is the key to making interfaces more effective. We argue that informal user interfaces, which do little or no up-front recognition of the perceptual input, have important applications and should not be forgotten by perceptual user interface researchers.