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Title: The steady state visual evoked potential as a paradigm for viable brain-computer interfaces
Author: Wilson, John J.
ISNI:       0000 0004 2736 4891
Awarding Body: University of Essex
Current Institution: University of Essex
Date of Award: 2012
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A brain-computer interface (BCl) establishes a new pathway for control and communication that occurs directly between the brain and an external device. The concept of bypassing traditional physical motor control is compelling to all, but particularly relevant to those that because of perhaps accident or disease, are unable to, or have difficulty performing routine tasks such as verbal communication or ,i A' . Iv., _ typing on a keyboard. The steady state visual evoked potential (SSVEP) is. among one of the most efficient BCI paradigms in terms of information transfer rate (ITR) with reported communication rates approaching that of more widely available low cost augmentative and alternative communication (AAC) systems such as switches and indirect scanning systems. To achieve these performance levels SSVEP BCls have tended to rely on empirical training periods for each user to ensure successful online classification. This thesis introduces techniques that produce comparable ITR's using standard criterion levels across all users, alleviating the need for a training period. Previous SSVEP BCl's have discarded phase information classifying response in the magnitude domain alone. It is revealed that important information is encoded in the phase of the SSVEP and incorporating it can lead to increased ITR. In addition intra phase coherency as a metric is particularly suited to proportional control in inherently analogue BCI tasks such as the movement of a mouse pointer. Furthermore it is demonstrated how use of absolute phase solves fundamental limitations in the number of targets displayable on conventional computer displays but creates its own additional hardware constraints and signal contamination issues. The impact of popular stimulation methods on phase consistency is investigated along with target layout methods to counter these new constraints.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available