A method for visual psychophysics based on the navigational behavior of desert ants (Melophorus bagoti)

The Australian desert ant Melophorus bagoti is known to navigate in its complex visual environment relying on path integration and landmark learning. We investigated the navigational behavior of desert ants in response to visual stimulus changes along their route to a food source. Ants were trained to self-navigate a track between their nest and a feeder, with visual stimuli placed near the feeder. After 3 days of training, we altered the visual scene by changing colors and observed the ants' reactions. The results showed that when visual changes were introduced, the ants displayed more meandering paths, more scanning behavior, and slower speeds compared with control conditions. In addition, changes in color led to significantly higher amplitudes of head oscillations and path oscillations. These findings suggest that changes to visual cues used for navigation cause noticeable changes in their movement patterns and that ants are sensitive to color (to the hue, brightness, or both) in navigation. Noting changes in speed and straightness, which are easy to measure and calculate, provides a suitable signature to indicate that ants have detected a change in the visual stimuli. This proof-of-concept study thus highlights a method for studying visual psychophysics in ants in their natural habitat.