Fig. 1: Mean reading times and difference-adjusted 95% (percentile) mixed-effect-model-based intervals (Politzer-Ahles, 2017).
From: Object type effects on the processing of Chinese aspectual verbs in complement coercion

The intervals roughly indicate significant differences between conditions: If the interval range of one condition does not overlap with the mean of another and vice versa, it suggests a statistically significant difference between those conditions within a mixed-effect model.