Critical decision-speed and information transfer in the Graz Brain-Computer interface

The "Graz Brain-Computer Interface (BCI)" transforms changes in oscillatory EEG activity into control signals for external devices and feedback. These changes are induced by various motor imageries performed by the user. For this study, 2 different types of motor imagery (movement of the r...

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Bibliographic Details
Published in:Applied psychophysiology and biofeedback 2003-09, Vol.28 (3), p.233-240
Main Authors: KRAUSZ, G, SCHERER, R, KORISEK, G, PFURTSCHELLER, G
Format: Article
Language:English
Subjects:
Adult
Behavioral psychophysiology
Biological and medical sciences
Cerebral Cortex - physiology
Decision Making
Electroencephalography
Electrophysiology
Feedback, Psychological
Fundamental and applied biological sciences. Psychology
Humans
Imagery (Psychotherapy)
Male
Mental Processes
Motor Skills
Paraplegia - rehabilitation
Psychology. Psychoanalysis. Psychiatry
Psychology. Psychophysiology
Task Performance and Analysis
User-Computer Interface
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Summary:The "Graz Brain-Computer Interface (BCI)" transforms changes in oscillatory EEG activity into control signals for external devices and feedback. These changes are induced by various motor imageries performed by the user. For this study, 2 different types of motor imagery (movement of the right vs. left hand or both feet) were classified by processing 2 bipolar EEG-channels (derived at electrode positions C3 and C4). After a few sessions, within some weeks, 4 young paraplegic patients learned to control the BCI. In accordance with the participants, decision-speed (trial length) was varied and the information transfer rate (ITR) was calculated for each run. All experimental runs have been feedback-runs employing a simple computer-game-like paradigm. A falling ball had to be led into a randomly marked target halfway down the screen. The horizontal position was controlled by the BCI-output signal and the trial length was varied by the investigator across runs. The goal was to find values for trial length enabling a maximum ITR. Three out of 4 participants had good results after a few runs. Analysis of their last 2 experimental sessions, each containing between 10 and 16 runs, showed that the trial length can be reduced to values around 2 s to obtain the highest possible information transfer. Attainable ITRs were between 5 and 17 bit/min depending on the participant's performance and condition.
ISSN:1090-0586
1573-3270
DOI:10.1023/A:1024637331493