Speed of illusory body movements alters the passage of time

Your brain has a remarkable ability to extract and process biological cues from the deluge of visual information. It is highly sensitive to the movements of living things, especially those of other people – so much so that it conjures the illusion of movement from a picture of a moving body. Although static, such pictures trigger dynamic representations of the body, ‘motor images’ containing information about movement kinematics and timing. Researchers at the Institute of Cognitive Neuroscience in London now show that biological motion is processed unconsciously, and that the speed of apparent motion alters the perception of time.

Play around with this point light display and you’ll see that your brain has specialized mechanisms dedicated to recognizing and visually processing the human body and its movements. The demo shows that the brain is adept at inferring structure from motion, so thatwe readily perceive biological motion even when a minimum amount of information about the body is available. It also shows that the motions of the body contain information about sex, weight, emotional state and even some personality traits, and that we can extract this information effortlessly.

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Box jellyfish stable-eyes vision to hunt prey

Ernst Haeckel’s Kunstformen der Natur (Artforms of Nature) was a landmark in biological illustration. Published in 1904, it was lavishly illustrated with 100 exquisitely detailed lithographic plates, including the one above, showing different species of cubomedusae, or box jellyfish. Since around the time that Haeckel’s masterpiece was published, we’ve known that box jellyfish have a unique visual system which is more sophisticated than that of other jellyfish species. They boast an impressive set of 24 eyes of four different types, which are clustered within bizarre sensory appendages that dangle from the cube-shaped umbrella.

The known light-guided behaviours of these organisms are, however, relatively simple, so exactly why they possess such an elaborate array of eyes was somewhat puzzling. A group of Scandinavian researchers working in the Caribbean now report that one of the box jelly’s eye types is highly specialized to peer up towards the water surface at all times, so that it can use terrestrial landmarks to navigate towards its prey.

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