Abstract:Multi mode brain computer interface is a system composed of a single mode brain computer interface and other single mode brain computer interfaces or other devices, which helps to remedy the "brain computer interface blindness" problem of a single mode brain computer interface. From the perspective of body phenomenology, the essence of multimodal brain computer interfaces is otherness perception. However, there are still theoretical difficulties in the perception of otherness in multimodal brain computer interfaces. In the future, increasing as many modalities as possible and synthesizing them will help improve the accuracy of multimodal brain computer interfaces in perceiving otherness. The multimodal brain computer interface has broad application prospects in areas such as healthcare, digital education, and smart homes.