Scanning behavior occurs with the same frequency and for the same duration regardless of the presence or absence of a stimulus.

<p>The duration of scans is represented here for 99 scans from 18 individuals presented with a stimulus (black) and 84 scans in 18 individuals not presented with a stimulus (gray). We found no significant difference in scan duration when a stimulus was present (p>0.7, Kolmogrov-Smirnov test). Inset: the average number of scans for a 5 minute trial in leeches with and without a vibratory (multimodal) stimulus. We found no significant increase in the number of searches when a stimulus was present (p>0.74, Kolmogrov-Smirnov).