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Are there animals which can see movements better than shapes or colors?

Are there animals which can see movements better than shapes or colors?


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I remember that in Michael Crichton's novel Jurassic Park, Tyrannosaurus Rex was supposed to have movement based vision. (Of course, that is a novel and not a scientific text.)

I have also noticed while feeding chickens, that they behave differently when they see me adding the food for them into the container as opposed to leaving it there for them when they cannot see me. (But this can be explained easily by different reasons, for example they are used to human as a source of their food, so they naturally go close to them.)

So my question is:

Are there some kinds of animals who have primarily movement based vision? If yes, which animals are examples for this?


The Michael Crichton's novel has been widely discussed online, I found for example this and several answers at Yahoo Answers. Frogs and reptiles are mentioned there.


I think "movement-based vision" is perhaps a bit of a misnomer. Ultimately, all vision is contrast-based, depending on integrating signals from ON and OFF bipolar cells. It seems that this notion of so-called "movement-based vision" is derived from work on toad vision and feature detection. In this case, it's more the downstream processing that results in different behavior based on the shape of the stimulus and the direction that it moves. The simple sensing of visual stimuli does not seem to be motion-based.

So, aside from evolutionary inference, we would have no way of knowing whether Tyranassaurus rex had such behavior. As for the chickens, it's possible but I would be skeptical of such a system discriminating between immobile food and hand pouring food. I would chalk that up to a simple behavior of associating seeing you with getting food.

One interesting note: many, many species have reflexive responses to moving visual stimuli. The first is called the optokinetic reflex, in which the eyes reflexively track contrast-based movement; and the second is the optomotor response, in which the head or even the whole body move in response to a moving stimulus. Thus it is safe to say that for many (most?) species, motion detection has a strong influence on the visual response… but again, I remain hesitant to use the phrase "motion-based vision".


Nocturnal owls may present a good example of an animal with greater sensitivity to movement than color. While they also rely heavily on good hearing, many owls like the Scops Owl referenced in the link below (time~ 5m 58s), rely heavily on detecting movement rather than color. Other nocturnal predators that rely on vision, such as many felids (e.g. ocelot), may provide further examples.

http://www.youtube.com/watch?v=ShPhYUQmRN8#t=05m58s


There certainly are many adaptations in the light receptors in the eyes that enhance contrast, color sensing, color discrimination as well as feature and movement sensitivity.

In school we usually learn about the cone and rod cells which are color and contrast sensitive in humans. Humans have only 3 types of cone receptors, the record may be 16 types of cone receptors. Many animals have no cone receptors and don't see color. The highly polychromatic mantis shrimp with 16 color receptors mentioned here may devote most of its brain power to motion sensing and little to color or feature parsing.

Motion sensing is not only wired in the brain, but the neural layers within the retina also generate neural signals when motion happens in the eye. In the case of human beings the rod cells generate motion sensitivity… Individual cell groups can cue to motion in a specific direction before passing off to the brain, which really helps with the reflex time.

All this takes a lot of brain power and the density of the cone cell density is highest in the center of your field of vision.

The density and the neural structure of the retina is highly flexible, adaptable to many configurations. Humans have a circular patch of high density cone receptors, cheetah have a long vertical streak of them which help them track prey when running at speeds over 60 miles per hour.

All this being said, its unlikely that an animal would only see movement, especially a larger on. In Jurassic park, the tyrannosaurus motion only eyes was a dramatic twist - its hard to imagine an animal having such a huge blindspot. Indeed this specific theory is now mostly discounted.


Even for humans, without saccades we do not have visual perception. Visual system easily adapts to things that do not change. There have been several experiments with human that shows this. Microsaccades are essential. I am busy at a conference now, but if nobody else answers in detail, I'll expand this answer in a couple of weeks with proper references.



Comments:

  1. Grogami

    You have hit the spot. There is something in this and a good idea, I agree with you.

  2. Lauraine

    Curiously, and the analogue is?

  3. Arajora

    Who told you that?

  4. Boyce

    Excuse me, the question is removed



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