two data points for illusion and mimicry

From: Wade T.Smith (wade_smith@harvard.edu)
Date: Thu Nov 22 2001 - 18:58:34 GMT

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    Subject: two data points for illusion and mimicry
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    OBSERVATORY

    Why Time Stands Still

    By HENRY FOUNTAIN

    http://www.nytimes.com/2001/11/20/science/20OBSE.html?pagewanted=print

    Why Time Stands Still

    Time marches on except when you turn your gaze toward a clock with a
    second hand. Then, in what is a common illusion, the hand can appear to
    have stopped, momentarily, before it moves again.

    Researchers in Britain have now shown why this illusion occurs, and say
    it is related to what happens when the eyes move from one fixed point to
    another, known as a saccade. Vision is blurred during the hundred
    milliseconds or so of a saccade, so the brain is unable to determine with
    certainty whether any objects in the field of view have changed
    positions. So the brain extends the perception of the target the clock,
    with its second hand in a specific position back in time to the
    beginning of the eye movement. This can make it seem as if the second
    hand were in that position for longer than it actually is.

    The researchers performed experiments using human subjects who focused on
    one point on a computer screen, moved their eyes to focus on a numeric
    counter that changed every second (the digital equivalent of a second
    hand) and then estimated how long the first digit was on the screen
    compared with the succeeding ones. The subjects consistently
    overestimated the duration of the first digit.

    When the experiment was altered so the counter changed position while the
    eyes were moving, no time illusion was experienced. This, the researchers
    wrote in the journal Nature, shows that the phenomenon is linked to the
    brain's assuming that the target is fixed during the eye movement.

    There's no word on whether the researchers are now turning their
    attention to the question of why a watched pot never boils.

    Coldblooded Behavior

    It's a fact of life in the animal world: males sometimes imitate females.
    The behavior is usually seen as a mating strategy a male that mimics a
    female's appearance, say, may avoid aggression by larger males and
    eventually get the partner of its dreams.

    But a study of male garter snakes suggests another reason for female
    mimicry, and love's got nothing to do with it. It's all about staying
    warm.

    Biologists at the University of Sydney in Australia and the University of
    Oregon studied red-sided garter snakes in Manitoba. These snakes mate in
    large groups in their dens, with as many as 100 males writhing around one
    or just a few females in what is known as a mating ball.

    In the first day or two after emerging from hibernation, when they are
    cold and slow, male snakes produce femalelike pheromones. This attracts
    already warm males who form a mating ball around the just-emerged snake.
    The ball, the researchers suggest in Nature, protects the weak snake from
    potential predators like crows. But more important, all that pressing the
    flesh warms the snake up quickly.

    By attaching tiny thermal sensors to the snakes, the researchers found
    that a garter could go from about 40 degrees Fahrenheit to about 70
    degrees in half an hour. And when you're coldblooded, every bit of heat
    helps.

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