It represents a relevant issue, since a wrong selection could turn into an error in communication, with both practical and psychological consequences for the user. In order to avoid it, the BCI system must be equipped with options that allow a user to correct wrong selections. A balance between speed and accuracy should be identified. Besides, accuracy is diminished also by the close temporal proximity of multiple target stimulus presentation. More specifically, the close temporal proximity of target stimuli leads to severely diminished accuracy (Martens et al. 2009; Salvaris and Sepulveda

2009; Citi et al. Inhibitors,research,lifescience,medical 2010). Although this phenomenon may have been detected early on (Serby et al. 2005), recently a more concerted effort has been observed in the literature in order to try to overcome such limitation. Moreover, technical challenges are related

to the recording quality in environment different from the laboratory setting, such as the user home, when different sources of noise can disturb the EEG recording (Sellers et al. 2006). Besides, Inhibitors,research,lifescience,medical the patient respirators may introduce electrical or mechanical artifacts. In the end, perceptual and cognitive abilities, in particular the capacity to pay selective and sustained attention to the target stimuli must Inhibitors,research,lifescience,medical be considered when employing P300 with neurological patients. It is necessary to determine whether or not a user is able not only to see the computer display, but also to focus on a particular stimulus on the display. Furthermore, since using a P300-BCI requires attention and concentration and interference may occur between counting the number of flashes of the matrix cell and simultaneously

concentrating on the characters to be selected, the user should not be distracted. Therefore, it may be difficult to use P300 Inhibitors,research,lifescience,medical in everyday life. Some pilot Inhibitors,research,lifescience,medical studies have shown that some NVP-AEW541 datasheet patients may not be able to learn the necessary skills for proper and effective use of the P300-based BCI, due to an excessive distractibility and an incapacity to tolerate a long-term training (Kubler et al. 1999; Hill et al. 2006). Other issues that may be problematic, especially during the initial stages of training with the BCI, are the boredom and the frustration that are sometimes reported by the patients themselves. However, a recent study shows that motivational aspects are positively correlated during with performance related to the BCI, by suggesting that highly motivated patients can get good results from the use of BCI as a communication tool; besides, some benefits with regard to patients psychological well-being seem to arise from satisfaction for the obtained results (Martens et al. 2009; Kleih et al. 2010). When planning to use P300 as an AAC device, it should be taken into account that the use of such technology is not always easy to understand for the patient and often a training is needed, which should involve both the patient and his/her family.