Multifractality in Typing as a Marker of Fatigue

Abstract

Multifractality is a property of biological signals that tells us about multi-scale patterns in the coordination of behaviour. Multifractality in behaviour is known to vary in response to factors --- like skill, engagement, and age-related decline --- which influence our ability to coordinate behaviour during tasks. Since fatigue also undermines behavioural coordination, this suggests multifractal signatures may also function as markers of fatigue.As such we conduct a study to investigate whether multifractal signatures in typing may function as markers of fatigue. We find that multifractality in typing is significantly lower after exposure to a mentally fatiguing task, and that multifractal properties correlate more strongly with degree of self-reported fatigue than other keystroke based measures. Multifractal analysis of typing requires only the capture of keystroke timings, pointing to its value as a cost-effective, unobtrusive and privacy supportive measure of fatigue in everyday tasks. Further, the presence of multifractality in a range of behaviours suggests the approach might also be effective in a range of interaction modalities beyond typing.

Keywords: fatigue, multifractality, interaction dominance, cognitive ergonomics, typing