Novel 9-Class Auditory ERP Paradigm Driving a Predictive Text Entry System
By Hoehne, Johannes; Schreuder, Martijn; Blankertz, Benjamin; Tangermann, Michael; Frontiers in Neuroscience, Volume 5, Number 99Publication Date: August 2011
Paper presents a novel approach to driving a brain-computer interface (BCI) based on event related potentials (ERPs) using auditory evoked potentials for the example of a multiclass text spelling application. Unlike most visual ERP-based BCI paradigms, which require good control of the user’s gaze direction, auditory BCI paradigms overcome this restriction. To control the ERP speller, BCI users focus their attention on two-dimensional auditory stimuli that vary in both pitch and direction and that are presented via headphones. The resulting 3-by-3 design: high, medium, low pitch and left, middle, right direction, offers an arrangement of 9 stimuli that are easy to discriminate from each other. The control signals are exploited to drive a predictive text entry system. It enables the user to spell a letter by a single 9 class decision plus 2 additional decisions to confirm a spelled word. This paradigm was named Predictive Auditory Spatial Speller with two-dimensional stimuli, or PASS2D. The paradigm was investigated in an online study with 12 healthy participants aged 21 to 34 years, 9 of whom were male. Participants spelled at an average rate of more than 0.8 characters, or 3.4 bits, per minute. Based on study results, the authors conclude that PASS2D is a competitive method which could enrich the toolbox of existing ERP paradigms for BCI end users such as individuals with late stage amyotrophic lateral sclerosis.
Published by: Frontiers Research Foundation (Website:http://www.frontiersin.org)
Link to text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3163907/
