When cognitive fit outweighs cognitive load: Redundant data labels in charts increase accuracy and speed of information extraction

In the online experiment presented in this paper, we investigated the effect of data labels in line and bar charts on users' accuracy and speed in solving chart-related business tasks dependent on different task types. Our results reveal that users perceive charts with redundant labels as significantly more efficient and answer related questions significantly more accurate and faster, which we explain by the help of cognitive fit theory. We provide valuable insights into cognitive processing of charts and encourage graph designers to consider redundant elements as a possible means to increase efficiency under particular circumstances.