What you expect is what you get? potential use of contingent negative variation for passive BCI systems in gaze-based HCI

  • Authors:
  • Klas Ihme;Thorsten Oliver Zander

  • Affiliations:
  • Team PhyPA, Chair of Human-Machine Systems, TU Berlin, Germany and Clinic for Psychosomatic Medicine and Psychotherapy, University Hospital Leipzig, Germany;Team PhyPA, Chair of Human-Machine Systems, TU Berlin, Germany and Max-Planck-Institute for Biological Cybernetics, Tuebingen, Germany

  • Venue:
  • ACII'11 Proceedings of the 4th international conference on Affective computing and intelligent interaction - Volume Part II
  • Year:
  • 2011

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Abstract

When using eye movements for cursor control in humancomputer interaction (HCI), it may be difficult to find an appropriate substitute for the click operation. Most approaches make use of dwell times. However, in this context the so-called Midas-Touch-Problem occurs which means that the system wrongly interprets fixations due to long processing times or spontaneous dwellings of the user as command. Lately it has been shown that brain-computer interface (BCI) input bears good prospects to overcome this problem using imagined hand movements to elicit a selection. The current approach tries to develop this idea further by exploring potential signals for the use in a passive BCI, which would have the advantage that the brain signals used as input are generated automatically without conscious effort of the user. To explore event-related potentials (ERPs) giving information about the user's intention to select an object, 32-channel electroencephalography (EEG) was recorded from ten participants interacting with a dwell-time-based system. Comparing ERP signals during the dwell time with those occurring during fixations on a neutral cross hair, a sustained negative slow cortical potential at central electrode sites was revealed. This negativity might be a contingent negative variation (CNV) reflecting the participants' anticipation of the upcoming selection. Offline classification suggests that the CNV is detectable in single trial (mean accuracy 74.9 %). In future, research on the CNV should be accomplished to ensure its stable occurence in human-computer interaction and render possible its use as a potential substitue for the click operation.