Visual attention-related processes in desert locusts' collective-motion-related decision-making

Collective motion is generated and sustained by locally interacting individuals in the group, navigating within a crowded and noisy social environment. Although it is widely accepted that collective-motion sensory processing involves focusing on the most behaviourally relevant cues, the underlying cognitive mechanisms remain poorly understood. Here, we tested for the presence of attention-related processes in marching last-instar nymphs of the desert locust. Using carefully controlled visual stimuli presented to individually tethered locusts in a natural walking posture, we integrated the evaluation of body kinematics and gaze direction to investigate two attention-related strategies: spatial selective attention and gaze-shift movements. Our results indicate that locusts are sensitive to specific swarming-related features independent of their position within the visual field. Moreover, the nymphs exhibited complex behavioural responses to conflicting scenarios, suggesting attention-related selectivity, with distinct gaze-shift patterns that facilitate visual processing. Our findings highlight the complexity of the cognitive mechanisms underlying vision-based, swarming-related decision-making in desert locusts, mechanisms that are likely common to other organisms engaged in collective motion.