Correct distance measurement is possible without optic flow cues.

(A) Median of 1. TPs and relative search density (RSD) plot of 0-00-experiment (n = 26). Ants of this sham control group were able to perceive optic flow during the entire experimental procedure. However, between I. Training and II. Test, eye caps were applied and removed 30s afterwards. (B) Median of 1. TPs and relative search density (RSD) plot of 1-11-experiment (n = 26). Ants were deprived of ventral optic flow cues during the entire experimental procedure. Release point (0) and fictive nest position (10) are marked by grey vertical lines, and 1. TP medians by coloured lines, in this and the following figures. (C) Box-and-whisker plots and statistical analysis. There is no statistically significant difference between the grand medians of the 0–00 and the 1–11 groups, demonstrating correct distance estimation for both groups. Nevertheless, the RSD-plot reveals a narrower search distribution of the 1-11-experiment, the reason remaining unclear.