Keystroke Dynamics Predict Essay Quality

Language entails many nested time scales, ranging from the relatively slow scale of cultural evolution to the rapid scale of individual cognition. The nested, multiscale nature of language implies that even simple acts of text production, such as typing a sentence, entail complex interactions involving multiple concurrent processes. As such, text production may have much in common with other cognitive phenomena thought to emerge from multiplicative interactions across temporal scales, namely those that exhibit fractal properties. We investigated the relationship between fractal scaling and the quality of produced text. Participants (N=131) wrote essays while their keystrokes were recorded. Fractal analyses were then performed on time series of interkeystroke intervals (IKIs). Results showed that fractal properties characterizing IKIs positively predicted expert ratings of essay quality, even after accounting for essay length. The results support our hypotheses concerning multiscale coordination and text production.