Graduate School of Informatics /Cognitive Science

In partial fulfillment of the requirements for the degree of Master of Science uğur Acar will defend his thesis.

Title: COGNITIVE ASPECTS OF BRAIN-COMPUTER COMMUNICATION: AN IMPLEMENTATION AND EXTENSION OF THE P300 SPELLER PARADIGM

Date: 15th March 2018

Time: 09:00 AM

Place: A-108

Thesis Abstract :Recently, advances in Brain Computer Interface (BCI) Devices have enabled access by a wider population of end users. Such devices are usually based on neuroimaging techniques such as Electroencephalography (EEG), which pick up characteristic brainwave signatures such as P300 event-related potentials (ERP). In this model, three types of stimuli will be presented. The first type are alphabet letters, the second type are symbols for basic needs, and the last type are words for creation of sentences. Simple sentences may be created including subject, object, and verb. Technically the present model has two parts, a training phase and a testing (prediction) phase. In the training phase, the user concentrates on one of the stimuli among the entire set of alternative stimuli and the application detects a P300 ERP for that target stimulus which captures the selection of the subject. The training phase is used for understanding the neural patterns of each user and thus, it generates a user-specific training model. After the completion of the training phase, the subject will be able to use the application for communication purposes. In the subsequent test phase, the subject will carry out two sets of tasks. First, subjects will use the three sets of items (letters, icons, and words), and create pre-specified target items, e.g., words (from letters), icon sequences, and sentences (from words). In case of incongruence of the intended and the produced item (by the application), a N400 ERP is expected, which will be statistically analyzed. Second, subjects will be given a number of action assignments for whose realization they are free to choose any of the three sets of units (letters, icons, and words). Cognitive strategies underlying the choice of units for efficient communication will be analyzed. In sum, the proposed thesis aims at combining technical and cognitive aspects of the usage of BCI devices for communication.