EEG and Eye-Tracking Error-Related Responses During Predictive Text Interactions: A BCI Case Study.

Brain-computer interfaces (BCIs) employ various paradigms which afford intuitive, augmented control for users to navigate digital technologies. In this study we explore the application of these BCI concepts to predictive text systems: commonplace interactive and assistive tools with variable usage contexts and user behaviors. We conducted an experiment to analyze user neurophysiological responses under these different usage scenarios and evaluate the feasibility of a closed-loop, adaptive BCI for use with such technologies. We recorded electroencephalogram (EEG) and eye tracking (ET) data from participants while they completed a self-paced typing task in a simulated predictive text environment. Participants completed the task with different degrees of reliance on the predictive text system (completely dependent, completely independent, or their choice) and encountered both correct and incorrect text generations. Data suggest that erroneous text generations may evoke neurophysiological responses that can be measured with both EEG and pupillometry. Moreover, these responses appear to change according to users' reliance on the predictive text system. Results show promise for use in a passive, hybrid, BCI with a closed-loop, adaptive framework, and support a neurophysiological approach to the challenge of real-time human feedback on system performance.

Understanding Divergent Thermal Conductivity in Single Polythiophene Chains Using Green-Kubo Modal Analysis and Sonification.

We used molecular dynamics simulations and the Green-Kubo modal analysis (GKMA) method as well as sonification to study the modal contributions to thermal conductivity in individual polythiophene chains. The simulations suggest that it is possible to achieve divergent thermal conductivity in individual polythiophene chains of certain lengths, with periodic boundary conditions. Application of the GKMA method further allowed for exact pinpointing of the modes responsible for the anomalous behavior. The analysis showed that transverse vibrations in the plane of the aromatic rings at low frequencies ∼0.05 THz are primarily responsible for the divergence. Within the integration time, one mode in particular exhibits a thermal conductivity contribution greater than 100 W m-1 K-1. Further investigation showed that the divergence arises from persistent correlation between the three lowest frequency modes on chains that have exact multiples of 30 unit cells in length. Sonification of the mode heat fluxes revealed regions where the heat flux amplitude yields a somewhat sinusoidal envelope with a long period similar to the relaxation time. This characteristic in the divergent mode heat fluxes gives rise to the overall thermal conductivity divergence, which strongly supports earlier hypotheses that attribute the divergence to correlated phonon-phonon scattering/interactions as opposed to a lack of scattering/interaction among modes (e.g., infinite relaxation time/ballistic transport).