A shaping procedure to modulate two cognitive tasks to improve a sensorimotor rhythm-based brain-computer interface systems

This study aimed to propose an adapted feedback using a psychological learning technique based on Skinner's shaping method to help the users to modulate two cognitive tasks (right-hand motor imagination and relaxed state) and improve better control in a Brain-Computer Interface. In the first experiment, a comparative study between performance in standard feedback (N = 9) and shaping method (N = 10) was conducted. The NASA Task Load Index questionnaire was applied to measure the user's workload. In the second experiment, a single case study was performed (N = 5) to verify the continuous learning by the shaping method. The first experiment showed significant interaction effect between sessions and group (F(1, 17) = 5.565; p = .031) which the shaping paradigm was applied. A second interaction effect demonstrates a higher performance increase in the relax state task with shaping procedure (F(1, 17) = 5. 038; p = .038). In NASA-TXL an interaction effect was obtained between the group and the cognitive task in Mental Demand (F(1, 17) = 6, 809; p = .018), Performance (F(1, 17) = 5, 725; p = .029), and Frustration (F(1, 17) = 9, 735; p = .006), no significance was found in Effort. In the second experiment, a trial-by-trial analysis shows an ascendant trend learning curve for the cognitive task with the lowest initial acquisition (relax state). The results suggest the effectiveness of the shaping procedure to modulate brain rhythms, improving mainly the cognitive task with greater initial difficulty and provide better interaction perception

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Brain-computer interface: proposal of a shaping-based training

INTRODUCTION: Persons affected by certain motor disabilities such as amyotrophic lateral sclerosis can evolve with important motor and speech difficulties in communication. A BCI (Brain Computer Interface) is a system that allows interaction between the human brain and a computer, permitting the user to control a communication channel through his or her brain activity. It is based on the analysis and processing of electroencephalographic (EEG) signals to generate control commands. The present study focuses on the subjects' capability to improve the way they learn to control a BCI system. METHODS: Two training procedures were compared: standard and progressive shaping response. Six volunteers participated in a reversal single-subject ABAC design. RESULTS: The study showed that both procedures are equally effective in producing a differential responding in the EEG signals, with no significant differences between them. Nevertheless, there were significant differences when distinguishing two neuronal responses (relax state and hand-movement imagination). Also, in the analysis of individual signals, an adaptive process for the shaping process and a lower error rate in the idle response appeared. CONCLUSION: Both proposed training procedures, standard and progressive shaping, are equally effective to achieve training of differential responses (imagination of hand/relax) in the interaction with a BCI.

Variables psicológicas en el control de interfaces cerebro-computadora / Psychological variables in the control of brain-computer interfaces

BCI (Brain Computer Interface) es un sistema que permite la interacción entre el cerebro humano y un ordenador. Se basa en el análisis de señales electroencefalográficas (EEG) y el procesado de éstas para generar comandos de control. En el estudio se analizó la posible influencia de variables psicológicas como la capacidad imaginativa sinestésica y la ansiedad en relación al desempeño en un BCI. Todos los participantes (4 hombres y 19 mujeres estudiantes) realizaron los cuestionarios y una sesión de BCI para controlar con sus señales EEG un entorno virtual de un coche por una carretera recta. El grupo se dividió en dos subgrupos en función de que sus señales EEG consiguieran o no respuestas diferenciales en esa discriminación izquierda-derecha. Los resultados del estudio no mostraron diferencias significativas en las variables cognitivas de imaginación, ni tampoco en ansiedad. Al comparar ese grado de control BCI de los participantes se encontró un nuevo parámetro cuantitativo que permite comparar ejecuciones y tomar decisiones en el procesado de señales. Se discuten los hallazgos, el proceso de investigación en marcha para refinar el control de un BCI y la interacción de procedimientos psicológicos e informáticos (AU)

BCI (Brain-Computer Interface) is a system that allows interaction between the human brain and a computer. It is based on analyzing electroencephalographic signals (EEG) and processing them to generate control commands. The study analyzed the possible influence of psychological variables, such as the imaginative kinesthetic capacity and anxiety, in relation to performance in a BCI. All participants (4 male and 19 female students) completed the questionnaires and carried out a session of BCI to control their EEG signals in a virtual setting of a car along a straight road. The group was divided into two subgroups according to their EEG signals or differential responses obtained in the left-right discrimination. Study results showed no significant differences in cognitive variables of imagination or in anxiety. By comparing the degree of participants’ BCI control, a new quantitative parameter for comparing performances and making decisions in signal processing was found. The findings, the ongoing research process to refine the control of a BCI, and the interaction of psychological and computer procedures are discussed (AU)