Compatibility between Brain-Computer Interface and High Efficiency Augmentative and Alternative Communication Systems: Phase II ABSTRACT Brain-computer interfaces (BCI) enable text production for people who cannot move, but have only simple communication interfaces and are not widely used. Augmentative and alternative communication (AAC) systems are widely used and give efficient and precise communication, but require movement, preventing use by people with severe impairments, such as advanced amyotrophic lateral sclerosis or severe cerebral palsy. Our Phase I STTR created and tested a software prototype of BCI access to the extensive language application and communication system product line of the Prentke Romich Company (PRC). The prototype was evaluated by PRC users, each using the BCI to access a software replica of their everyday device. The overall objective of this Phase II application is to complete the hardware and software prototype of the AAC-BCI along with training and resource materials. Our Phase I efforts showed compatibility of BCI access to PRC software with gel electrode hardware. Users wanted shorter setup times, elimination of gel, and increased interface responsiveness. Clinicians and internet survey participants echoed this feedback and wanted easier setup and calibration, dry electrodes, and convenient training resources. Our central hypothesis is that a commercial-grade implementation of BCI access to PRC language applications using quick-setup dry electrodes with matching training and support resources will meet laboratory-testing goals for effective communication and be ready for future clinical trials on its ability to meet desired communication outcomes. Through studies with participants familiar with PRC’s AAC software and technology, we plan to test our central hypothesis and meet the objective of the application with the following specific aims: 1. Optimize user interface design to guide BCI setup and calibration, and to refine interface responsiveness and integration of BCI stimuli into existing device displays. 2. Create a commercial grade software implementation that integrates BCI functionally into the existing AAC system. 3. Compare performance and user opinion of dry electrodes versus gel (wet) electrodes as the input peripheral for the AAC-BCI system. 4. Implement and evaluate training and resource materials for AAC-BCI set-up and calibration with input from practitioners, potential users and their support people. This work will finalize a BCI input accessory for PRC’s line of AAC devices. The innovation of this work is merging BCI access with the high-efficiency language production from PRC’s AAC user interface designs that are matched to each person' abilities, needs, and preferences. The significance of this work is the extension of quality-of-life communication benefits to those with the most severe physical impairments, providing an AAC-BCI through an established company with a clinical support ...