Data from: Motion after-effects induced by dynamic illumination in crab vision

Motion detection is an elementary aspect of most animal visual systems.
However, many environments are prone to background motion which might
disrupt the ability of visual systems to detect relevant motion cues.
While in humans, background motion can disrupt the detection of visual
cues even after the moving background component has ceased, it remains
unknown whether natural forms of background motion might also affect other
animal visual systems. Here, we test whether prior exposure to naturally
occurring ‘caustics’, a form of dynamically moving light patterns commonly
found in shallow aquatic environments, can have a persisting effect on an
animal’s motion detection abilities even after the caustic exposure has
stopped. To do this, we established the response probability of the shore
crab Carcinus maenas to computer-generated expanding disc stimuli
mimicking an approaching predator after exposure to either static or
moving caustic scenes. Prior exposure to moving caustics had a short-term
persisting effect on visual perception in C. maenas, reducing crabs’
likelihood to respond to an approaching predator for at least two seconds
after the moving caustics had ceased. Our study shows that even after an
exposure period to background motion has ended, the visual response rates
in C. maenas can still be reduced for a short period owing to the prior
exposure. While this so-called ‘historical effect’ may derive from an
adaptation of the crab’s visual system to the caustic background motion,
we discuss whether it may have survival consequences for this crustacean
species.