Analysis of EEG Signals on Overt and Covert using P300 Speller

A Brain Computer Interface is an electronic device used for communication by patients with motor neuron disorders. With the use of a BCI the performance of rehabilitative techniques for patients with neuron disease shows improvement. The brain Electroencephalogram signals, detected and recorded by the BCI are used for analysis. These electrical signals by-pass the damaged neurons of the brain and are recorded by the device to capture and understand the patient¿s intent. The P300 component of ERP used for the detection of attention towards a character is a popular technique for analyzing the intent of patients. This proposed method works well in overt attention. But the signal to noise ratio of EEG signals is low which hinders the efficiency of communication. Hence, for efficient use of BCI, a new method is devised, based on the principle of covert based attention, where target appearing within the visual periphery of eye gaze is recorded as an ERP. This is the Geometric Speller that is used for patients with Locked-in Syndrome, i.e., those suffering from impaired or loss of eye movement. Hence the two devices are compared in the covert and overt attention.