Effects of object motion on visual acuity in honeybees.

Object motion is a fundamental visual cue for many animals, yet its role in modulating visual perception is not fully understood. The majority of previous studies have used stationary stimuli to investigate the visual acuity of insects such as honeybees. Here, we used a behavioural assay to investigate whether object motion influences the known bounds of bees' visual acuity. Using a Y-maze, we conducted binary choice experiments where honeybees (Apis mellifera) were trained to a stimulus and then tested with pairs of stimuli varying in shape (disc versus diamond), size and motion (stationary versus moving). When stimuli were stationary, bees perceived the change in shape only for targets that subtended visual angles >1.9 deg. However, when presented with a stationary and a moving stimulus, they consistently preferred the moving stimulus, even when both stimuli subtended angles as small as 0.44 deg. Furthermore, motion cues were found to override a learned preference for a familiar stationary shape. Most notably, bees successfully discriminated shapes at the smallest tested size of 0.44 deg when both targets were in motion, but not when they were stationary. These findings provide behavioural evidence that object motion can be a salient cue that not only drives choice but also enhances visual acuity in honeybees beyond previously established limits. This suggests that motion may facilitate the perception of fine spatial details and underscores the importance of incorporating dynamic cues when studying the sensory limits of animal vision.