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Fast and flexible selection with a single switch

Fast and flexible selection with a single switch. Tamara Broderick, UC Berkeley tab@stat.berkeley.edu David J.C. MacKay, University of Cambridge. Single-switch communication. “Single switch” Button press, blink, muscle movement, etc. Communication aids. One-button Dasher.

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Fast and flexible selection with a single switch

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  1. Fast and flexible selectionwith a single switch • Tamara Broderick, UC Berkeley • tab@stat.berkeley.edu • David J.C. MacKay, University of Cambridge

  2. Single-switch communication • “Single switch” • Button press, blink, muscle movement, etc. • Communication aids One-button Dasher Scanning (The Grid 2)

  3. Nomon • Select any points of interest on the screen

  4. Nomon • Select any points of interest on the screen [Nomon demo]

  5. Nomon operation • Posterior inference at each round • p(option | clicks)∝p(clicks | option)p(option) • Prior • Likelihood • Posterior

  6. Nomon operation p(option | clicks)∝p(clicks | option)p(option) • Prior (distribution over onscreen options) • e.g. Nomon keyboard • Preset priors to special characters/functions • Alphabetic characters and word completions: Laplace smoothing based on British National Corpus • Fixed in current Nomon implementation

  7. Nomon operation p(option | clicks)∝p(clicks | option)p(option) • Likelihood (click distribution around “noon”) • Initial estimate • Updated with a modified (damped) Parzen window estimator based on user clicks (on a delay) • Posterior (when to choose a clock for selection) • Choose probability of error (e.g. 5%) • Gives odds cutoff α (e.g. 0.95/0.05)

  8. Nomon operation p(option | clicks)∝p(clicks | option)p(option) • Likelihood (click distribution around “noon”) • Initial estimate • Updated with a modified (damped) Parzen window estimator based on user clicks (on a delay) • Posterior (when to choose a clock for selection) • Choose probability of error (e.g. 5%)

  9. Experiment • Sixteen able participants from U Cambridge • No previous experience with scanning (The Grid 2) or Nomon • £10 for each one-hour (one-interface) session; £5 bonus for writing above the median speed in a session

  10. Experiment • No difference in novice error rate • p=0.41, Nomon: 0.43%, Grid: 0.34% • Novices wrote 35% faster with Nomon • Faster in final block: p<10-8 • Each participant enjoyed using Nomon at least as much as the scanning software • Also, mean (sd) results on the 1[strongly disagree] to 7[strongly agree] scale: Nomon 5.6 (1.4), Grid 3.9 (1.5)

  11. Next • Target audience • Theoretical • clock representation • parameters • heuristics

  12. Acknowledgments • Thanks to Per Ola Kristensson, Geoffrey Hinton, Keith Vertanen, Philipp Hennig, Carl Scheffler, and Philip Sterne for helpful discussions • Funding from: Nine Tuna Foundation, Nokia • TB’s research at Cambridge was supported by a Marshall Scholarship • A free trial of The Grid 2 was generously provided by Sensory Software References • Download Nomon Keyboard and Nomon Draw: http://www.inference.phy.cam.ac.uk/nomon/ • Tamara Broderick and David J.C. MacKay. Fast and flexible selection with a single switch. PLoS ONE 4(10), e7481.

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