Schools sort themselves based on sensory noise. Individuals with higher sensory noise (depicted in purple) eventually move towards the tail of the group while blue individuals (with lesser sensory noise) lead the group. Such observations in the natural world can be mistaken for leadership. Even though the blue individuals appear to lead the group, the pattern emerges from the difference in sensory noise rather than individuals actively engaging in leadership
Schooling golden shiners (Notemigonus crysoleucas) have a natural preference for darker regions. Individuals respond to light levels at their location. They slow down in dark regions and speed up in bright regions. When moving through a gradient, variation in individuals speeds in combination with a desire to maintain group cohesion attributes the group the ability to track gradients.
In the video below, fish are navigating across a uniformly bright environment. The moving circle represents a gaussian peak of darkness, a region that the fish desire to be in (circle represents one standard deviation). The video depicts how individuals in a moving peak track it using social information