HSI 2013 Sopot, Poland, June 06-08, 2013 978-1-4673-5637-4/13/$31.00 ©2013 IEEE Abstract. Brain computer interface (BCI) systems allow interaction with machines through a channel that does not involve the traditional motor pathways of the human nervous system. Thus they can be used by people with severe motor disabilities or those whose limbs are occupied with other tasks. In BCI systems that recently showed greatest interest of researchers, electrical brain activity is measured on the scalp, thus basically they are noninvasive. Using the EEG measurements as the input to the BCI offers the advantages of low cost and high time resolution. However, due to small amplitude of the signal components, relatively high power of noise and poor spatial resolution, achieving large speed, accuracy and the number of targets is a challenge. At present, the steady-state visual evoked potential (SSVEP) BCI paradigm is believed to provide the most promising way of optimizing the BCI performance in that sense. A review of the SSVEP BCI projects is presented, including studies of biodiversity of human EEG response to visual excitation, as well as the design of techniques for visual stimulation, EEG signal acquisition and analysis for best BCI performance. The review is based both on the literature and results of own teamwork. Keywords: Brain-computer interface (BCI), Steady-state visual evoked potentials (SSVEP), Alternate half-field stimulation. I. INTRODUCTION HE number of “smart” devices and appliances around us grows quickly in the last decades. Not even computers, tablets, cellular phones do comprise a processor with a complex program. Operation and performance of cars, home appliances, such as washing machine, microwave oven, TV set, etc. strongly depend on the computational power and quality of software of the digital electronic systems embedded in it. The growth of the number of various applications of computers to daily life situations is tremendous and continues beyond imagination. Still, it seems the rate of progress in the performance of the computational systems is not accompanied by an equally fast development of the interfaces necessary for information exchange between machines and their users. As an example, for more than 40 years the standard man-machine interfaces for a personal computer are keyboard, LCD text/graphics display and a mouse. Especially the keyboard, whose principle of operation has not changed much since the invention of typewriter in the middle 19th century, does not meet users expectations. Even in its touchable version, the keyboard requires from its user a special training (which in most cases is not performed, in fact) and the speed of transferring the information from human to computer through this channel has not increased for the last 150 years. (May be there is a little increase in the speed of entering the plain text or commands – with the use of prompt dictionaries.) Anyway, using the keyboard requires unnatural repetitive movements of fingers. Computer use has been associated with musculoskeletal problems of the upper extremities: neck, shoulders, arms, etc. Several postures and behaviors have been suggested as related to these disorders, including position in which the hands are held, neck and shoulder position, wrist posture and hyperextension of the fingers, to name a few [1]. Research work on alternative man-computer interfaces, better utilizing natural ways of human communication are then very well justified, if not urgently needed. It is expected the new approaches will provide better functionality and speed, as well as will be easier to use and its usage will not cause severe disorders of the organs of the human body. Examples of the devices of this type are joystick, graphics tablet and touchpad, with software to recognize hands multi-touch and gestures. One should notice that almost all of the new interfaces (except perhaps speech recognition and text-to-speech software) require movements of the user limbs or fingers. However, there are groups of users who are not able to make such movements. There are fighter pilots or car drivers, whose limbs are occupied with some tasks. There are motor-impaired people, or persons paralyzed after accidents or neurological diseases who cannot move their limbs, cannot speak, but whose mind operates normally and they need ways of communication with the external world. Thus, there is a need to develop interfaces that would allow users to enter data into computers without involving the traditional motor pathways of the human nervous system. A solution is a brain-computer interface (BCI) [2]. Operation of a BCI is based on analysis of the activity of the brain and is independent of an activity of muscles or other nerves. In those interfaces, the intention/will of a user is not expressed by any movement, gesture or command; it is rather “guessed” by the analysis of some measured signals that reflect the brain activity. Research projects aimed at development of BCI started about 40 years ago. Some of them have already brought spectacular results, such as mind-controlled prosthesis developed at Technical University Graz [3]. Still, the BCI functionality is far from the expectations. This gives High-Speed Noninvasive Brain-Computer Interfaces A. Materka 1 , P. Poryzała 1 1 Lodz University of Technology, Lodz, Poland, andrzej.materka@p.lodz.pl, pawel.poryzala@p.lodz.pl T