Brain-computer interfaces (BCI) have potential to provide a new channel of communication and control for people with severe motor disabilities. Although many empirical studies exist, few have specifically evaluated the impact of contributing factors on user performance and perception in BCI applications, especially for users with motor disabilities. This article reports the effects of luminosity contrast and stimulus duration on user performance and usage preference in a P300-based BCI application, P300 Speller. Ten participants with neuromuscular disabilities (amyotrophic lateral sclerosis and cerebral palsy) and 10 able-bodied participants were asked to spell six 10-character phrases in the P300 Speller. The overall accuracy was 76.5% for the able-bodied participants and 26.8% for participants with motor disabilities. The results showed that luminosity contrast and stimulus duration have significant effects on user performance. In addition, participants preferred high luminosity contrast with middle or short stimulus duration. However, these effects on user performance and preference varied for participants with and without motor disabilities. The results also indicated that although most participants with motor disabilities can establish BCI control, BCI illiteracy does exist. These results of the study should provide insights into the future research of the BCI systems, especially the real-world applicability of the BCI applications as a nonmuscular communication and control system for people with severe motor disabilities.
Feature of event-related potential (ERP) has not been completely understood and illiteracy problem remains unsolved. To this end, P300 peak has been used as the feature of ERP in most brain–computer interface applications, but subjects who do not show such peak are common. Recent development of convolutional neural network provides a way to analyze spatial and temporal features of ERP. Here, we train the convolutional neural network with 2 convolutional layers whose feature maps represented spatial and temporal features of event-related potential. We have found that nonilliterate subjects' ERP show high correlation between occipital lobe and parietal lobe, whereas illiterate subjects only show correlation between neural activities from frontal lobe and central lobe. The nonilliterates showed peaks in P300, P500, and P700, whereas illiterates mostly showed peaks in around P700. P700 was strong in both subjects. We found that P700 peak may be the key feature of ERP as it appears in both illiterate and nonilliterate subjects.
In this study, we analyze the effect of a recliner chair with rocking motions on sleep quality of naps using automated sleep scoring and spindle detection models. The quality of sleep corresponding to the two rocking motions was measured quantitatively and qualitatively. For the quantitative evaluation, we conducted a sleep parameter analysis based on the results of the estimated sleep stages obtained on the brainwave and spindle estimation, and a sleep survey assessment from the participants was analyzed for the qualitative evaluation. The analysis showed that sleep in the recliner chair with rocking motions positively increased the duration of the spindles and deep sleep stage, resulting in improved sleep quality.
Objective: The aim of this study was to investigate the association between conceptual metaphors of affect and physical dimensions. Background: The evidence that affect is unconsciously linked to physical dimensions(e.g., position and color) has been obtained in western cultures. However, in eastern cultures, especially, in Korea, it has been seldom tested. It is indispensable to examine whether or not cultural differences exist for better understanding of the conceptual metaphors. Method: 50 positive and 50 negative words were adopted from previous studies in order to determine the relationship between physical domains and abstract affect. Three hypotheses were tested in this study: (1) Good is up. (2) Good is bright. (3) Good is right(for right-handers). The automatic association between valence(positive vs. negative) and vertical position (up vs. down) was investigated in experiment 1, in which 100 words were randomly presented on either the top or the bottom of a LCD screen and the evaluation time of the presented word was recorded. The unconscious association between valence and color(white and black) was examined in experiment 2, where each word was randomly presented in either white or black. Lastly, we tested whether right-handers tend to associate rightward space with positive ideas and leftward space with negative ideas. Results: Reaction time was faster when words were presented in metaphor congruent domains(e.g., 'positive words on the top, in bright color, and on right space vs. negative words on the bottom, in dark color, and on left region) than when they were shown in metaphor incongruent domains. Conclusion: The results might give the groundwork for various directions in further understanding perception, emotion, and behavior. Application: This study may provide useful points to GUI designers and service developers if further studies enhanced in validity and reliability are followed.
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